[v6] riscv: add support for SBI Supervisor Software Events

[PATCH v6 3/5] drivers: firmware: add riscv SSE support

Posted by Clément Léger 6 months ago

Add driver level interface to use RISC-V SSE arch support. This interface
allows registering SSE handlers, and receive them. This will be used by
PMU and GHES driver.

Signed-off-by: Himanshu Chauhan <hchauhan@ventanamicro.com>
Co-developed-by: Himanshu Chauhan <hchauhan@ventanamicro.com>
Signed-off-by: Clément Léger <cleger@rivosinc.com>
Acked-by: Conor Dooley <conor.dooley@microchip.com>
---
 MAINTAINERS                        |  15 +
 drivers/firmware/Kconfig           |   1 +
 drivers/firmware/Makefile          |   1 +
 drivers/firmware/riscv/Kconfig     |  15 +
 drivers/firmware/riscv/Makefile    |   3 +
 drivers/firmware/riscv/riscv_sse.c | 694 +++++++++++++++++++++++++++++
 include/linux/riscv_sse.h          |  56 +++
 7 files changed, 785 insertions(+)
 create mode 100644 drivers/firmware/riscv/Kconfig
 create mode 100644 drivers/firmware/riscv/Makefile
 create mode 100644 drivers/firmware/riscv/riscv_sse.c
 create mode 100644 include/linux/riscv_sse.h

diff --git a/MAINTAINERS b/MAINTAINERS
index bd62ad58a47f..114396d47f76 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -21640,6 +21640,13 @@ T:	git git://git.kernel.org/pub/scm/linux/kernel/git/iommu/linux.git
 F:	Documentation/devicetree/bindings/iommu/riscv,iommu.yaml
 F:	drivers/iommu/riscv/
 
+RISC-V FIRMWARE DRIVERS
+M:	Conor Dooley <conor@kernel.org>
+L:	linux-riscv@lists.infradead.org
+S:	Maintained
+T:	git git://git.kernel.org/pub/scm/linux/kernel/git/conor/linux.git
+F:	drivers/firmware/riscv/*
+
 RISC-V MICROCHIP FPGA SUPPORT
 M:	Conor Dooley <conor.dooley@microchip.com>
 M:	Daire McNamara <daire.mcnamara@microchip.com>
@@ -21704,6 +21711,14 @@ F:	arch/riscv/boot/dts/spacemit/
 N:	spacemit
 K:	spacemit
 
+RISC-V SSE DRIVER
+M:	Clément Léger <cleger@rivosinc.com>
+R:	Himanshu Chauhan <himanshu@thechauhan.dev>
+L:	linux-riscv@lists.infradead.org
+S:	Maintained
+F:	drivers/firmware/riscv/riscv_sse.c
+F:	include/linux/riscv_sse.h
+
 RISC-V THEAD SoC SUPPORT
 M:	Drew Fustini <fustini@kernel.org>
 M:	Guo Ren <guoren@kernel.org>
diff --git a/drivers/firmware/Kconfig b/drivers/firmware/Kconfig
index bbd2155d8483..1894df87b08e 100644
--- a/drivers/firmware/Kconfig
+++ b/drivers/firmware/Kconfig
@@ -294,6 +294,7 @@ source "drivers/firmware/meson/Kconfig"
 source "drivers/firmware/microchip/Kconfig"
 source "drivers/firmware/psci/Kconfig"
 source "drivers/firmware/qcom/Kconfig"
+source "drivers/firmware/riscv/Kconfig"
 source "drivers/firmware/samsung/Kconfig"
 source "drivers/firmware/smccc/Kconfig"
 source "drivers/firmware/tegra/Kconfig"
diff --git a/drivers/firmware/Makefile b/drivers/firmware/Makefile
index 4ddec2820c96..6cdd84570ea7 100644
--- a/drivers/firmware/Makefile
+++ b/drivers/firmware/Makefile
@@ -34,6 +34,7 @@ obj-y				+= efi/
 obj-y				+= imx/
 obj-y				+= psci/
 obj-y				+= qcom/
+obj-y				+= riscv/
 obj-y				+= samsung/
 obj-y				+= smccc/
 obj-y				+= tegra/
diff --git a/drivers/firmware/riscv/Kconfig b/drivers/firmware/riscv/Kconfig
new file mode 100644
index 000000000000..8056ed3262d9
--- /dev/null
+++ b/drivers/firmware/riscv/Kconfig
@@ -0,0 +1,15 @@
+# SPDX-License-Identifier: GPL-2.0-only
+menu "Risc-V Specific firmware drivers"
+depends on RISCV
+
+config RISCV_SSE
+	bool "Enable SBI Supervisor Software Events support"
+	depends on RISCV_SBI
+	default y
+	help
+	  The Supervisor Software Events support allow the SBI to deliver
+	  NMI-like notifications to the supervisor mode software. When enable,
+	  this option provides support to register callbacks on specific SSE
+	  events.
+
+endmenu
diff --git a/drivers/firmware/riscv/Makefile b/drivers/firmware/riscv/Makefile
new file mode 100644
index 000000000000..4ccfcbbc28ea
--- /dev/null
+++ b/drivers/firmware/riscv/Makefile
@@ -0,0 +1,3 @@
+# SPDX-License-Identifier: GPL-2.0
+
+obj-$(CONFIG_RISCV_SSE)		+= riscv_sse.o
diff --git a/drivers/firmware/riscv/riscv_sse.c b/drivers/firmware/riscv/riscv_sse.c
new file mode 100644
index 000000000000..edd107ade94a
--- /dev/null
+++ b/drivers/firmware/riscv/riscv_sse.c
@@ -0,0 +1,694 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (C) 2024 Rivos Inc.
+ */
+
+#define pr_fmt(fmt) "sse: " fmt
+
+#include <linux/cpu.h>
+#include <linux/cpuhotplug.h>
+#include <linux/cpu_pm.h>
+#include <linux/hardirq.h>
+#include <linux/list.h>
+#include <linux/percpu-defs.h>
+#include <linux/reboot.h>
+#include <linux/riscv_sse.h>
+#include <linux/slab.h>
+
+#include <asm/sbi.h>
+#include <asm/sse.h>
+
+struct sse_event {
+	struct list_head list;
+	u32 evt_id;
+	u32 priority;
+	sse_event_handler *handler;
+	void *handler_arg;
+	/* Only valid for global events */
+	unsigned int cpu;
+
+	union {
+		struct sse_registered_event *global;
+		struct sse_registered_event __percpu *local;
+	};
+};
+
+static int sse_hp_state;
+static bool sse_available __ro_after_init;
+static DEFINE_SPINLOCK(events_list_lock);
+static LIST_HEAD(events);
+static DEFINE_MUTEX(sse_mutex);
+
+struct sse_registered_event {
+	struct sse_event_arch_data arch;
+	struct sse_event *event;
+	unsigned long attr;
+	bool is_enabled;
+};
+
+void sse_handle_event(struct sse_event_arch_data *arch_event,
+		      struct pt_regs *regs)
+{
+	int ret;
+	struct sse_registered_event *reg_evt =
+		container_of(arch_event, struct sse_registered_event, arch);
+	struct sse_event *evt = reg_evt->event;
+
+	ret = evt->handler(evt->evt_id, evt->handler_arg, regs);
+	if (ret)
+		pr_warn("event %x handler failed with error %d\n", evt->evt_id, ret);
+}
+
+static struct sse_event *sse_event_get(u32 evt)
+{
+	struct sse_event *event = NULL;
+
+	scoped_guard(spinlock, &events_list_lock) {
+		list_for_each_entry(event, &events, list) {
+			if (event->evt_id == evt)
+				return event;
+		}
+	}
+
+	return NULL;
+}
+
+static phys_addr_t sse_event_get_attr_phys(struct sse_registered_event *reg_evt)
+{
+	phys_addr_t phys;
+	void *addr = &reg_evt->attr;
+
+	if (sse_event_is_global(reg_evt->event->evt_id))
+		phys = virt_to_phys(addr);
+	else
+		phys = per_cpu_ptr_to_phys(addr);
+
+	return phys;
+}
+
+static struct sse_registered_event *sse_get_reg_evt(struct sse_event *event)
+{
+	if (sse_event_is_global(event->evt_id))
+		return event->global;
+	else
+		return per_cpu_ptr(event->local, smp_processor_id());
+}
+
+static int sse_sbi_event_func(struct sse_event *event, unsigned long func)
+{
+	struct sbiret ret;
+	u32 evt = event->evt_id;
+	struct sse_registered_event *reg_evt = sse_get_reg_evt(event);
+
+	ret = sbi_ecall(SBI_EXT_SSE, func, evt, 0, 0, 0, 0, 0);
+	if (ret.error) {
+		pr_warn("Failed to execute func %lx, event %x, error %ld\n",
+			func, evt, ret.error);
+		return sbi_err_map_linux_errno(ret.error);
+	}
+
+	if (func == SBI_SSE_EVENT_DISABLE)
+		reg_evt->is_enabled = false;
+	else if (func == SBI_SSE_EVENT_ENABLE)
+		reg_evt->is_enabled = true;
+
+	return 0;
+}
+
+int sse_event_disable_local(struct sse_event *event)
+{
+	return sse_sbi_event_func(event, SBI_SSE_EVENT_DISABLE);
+}
+EXPORT_SYMBOL_GPL(sse_event_disable_local);
+
+int sse_event_enable_local(struct sse_event *event)
+{
+	return sse_sbi_event_func(event, SBI_SSE_EVENT_ENABLE);
+}
+EXPORT_SYMBOL_GPL(sse_event_enable_local);
+
+static int sse_event_attr_get_no_lock(struct sse_registered_event *reg_evt,
+				      unsigned long attr_id, unsigned long *val)
+{
+	struct sbiret sret;
+	u32 evt = reg_evt->event->evt_id;
+	unsigned long phys;
+
+	phys = sse_event_get_attr_phys(reg_evt);
+
+	sret = sbi_ecall(SBI_EXT_SSE, SBI_SSE_EVENT_ATTR_READ, evt, attr_id, 1,
+			 phys, 0, 0);
+	if (sret.error) {
+		pr_debug("Failed to get event %x attr %lx, error %ld\n", evt,
+			 attr_id, sret.error);
+		return sbi_err_map_linux_errno(sret.error);
+	}
+
+	*val = reg_evt->attr;
+
+	return 0;
+}
+
+static int sse_event_attr_set_nolock(struct sse_registered_event *reg_evt,
+				     unsigned long attr_id, unsigned long val)
+{
+	struct sbiret sret;
+	u32 evt = reg_evt->event->evt_id;
+	unsigned long phys;
+
+	reg_evt->attr = val;
+	phys = sse_event_get_attr_phys(reg_evt);
+
+	sret = sbi_ecall(SBI_EXT_SSE, SBI_SSE_EVENT_ATTR_WRITE, evt, attr_id, 1,
+			 phys, 0, 0);
+	if (sret.error)
+		pr_debug("Failed to set event %x attr %lx, error %ld\n", evt,
+			 attr_id, sret.error);
+
+	return sbi_err_map_linux_errno(sret.error);
+}
+
+static void sse_global_event_update_cpu(struct sse_event *event,
+					unsigned int cpu)
+{
+	struct sse_registered_event *reg_evt = event->global;
+
+	event->cpu = cpu;
+	arch_sse_event_update_cpu(&reg_evt->arch, cpu);
+}
+
+static int sse_event_set_target_cpu_nolock(struct sse_event *event,
+					   unsigned int cpu)
+{
+	unsigned int hart_id = cpuid_to_hartid_map(cpu);
+	struct sse_registered_event *reg_evt = event->global;
+	u32 evt = event->evt_id;
+	bool was_enabled;
+	int ret;
+
+	if (!sse_event_is_global(evt))
+		return -EINVAL;
+
+	was_enabled = reg_evt->is_enabled;
+	if (was_enabled)
+		sse_event_disable_local(event);
+
+	ret = sse_event_attr_set_nolock(reg_evt, SBI_SSE_ATTR_PREFERRED_HART,
+					hart_id);
+	if (ret == 0)
+		sse_global_event_update_cpu(event, cpu);
+
+	if (was_enabled)
+		sse_event_enable_local(event);
+
+	return 0;
+}
+
+int sse_event_set_target_cpu(struct sse_event *event, unsigned int cpu)
+{
+	int ret;
+
+	scoped_guard(mutex, &sse_mutex) {
+		scoped_guard(cpus_read_lock) {
+			if (!cpu_online(cpu))
+				return -EINVAL;
+
+			ret = sse_event_set_target_cpu_nolock(event, cpu);
+		}
+	}
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(sse_event_set_target_cpu);
+
+static int sse_event_init_registered(unsigned int cpu,
+				     struct sse_registered_event *reg_evt,
+				     struct sse_event *event)
+{
+	reg_evt->event = event;
+
+	return arch_sse_init_event(&reg_evt->arch, event->evt_id, cpu);
+}
+
+static void sse_event_free_registered(struct sse_registered_event *reg_evt)
+{
+	arch_sse_free_event(&reg_evt->arch);
+}
+
+static int sse_event_alloc_global(struct sse_event *event)
+{
+	int err;
+	struct sse_registered_event *reg_evt;
+
+	reg_evt = kzalloc(sizeof(*reg_evt), GFP_KERNEL);
+	if (!reg_evt)
+		return -ENOMEM;
+
+	event->global = reg_evt;
+	err = sse_event_init_registered(smp_processor_id(), reg_evt, event);
+	if (err)
+		kfree(reg_evt);
+
+	return err;
+}
+
+static int sse_event_alloc_local(struct sse_event *event)
+{
+	int err;
+	unsigned int cpu, err_cpu;
+	struct sse_registered_event *reg_evt;
+	struct sse_registered_event __percpu *reg_evts;
+
+	reg_evts = alloc_percpu(struct sse_registered_event);
+	if (!reg_evts)
+		return -ENOMEM;
+
+	event->local = reg_evts;
+
+	for_each_possible_cpu(cpu) {
+		reg_evt = per_cpu_ptr(reg_evts, cpu);
+		err = sse_event_init_registered(cpu, reg_evt, event);
+		if (err) {
+			err_cpu = cpu;
+			goto err_free_per_cpu;
+		}
+	}
+
+	return 0;
+
+err_free_per_cpu:
+	for_each_possible_cpu(cpu) {
+		if (cpu == err_cpu)
+			break;
+		reg_evt = per_cpu_ptr(reg_evts, cpu);
+		sse_event_free_registered(reg_evt);
+	}
+
+	free_percpu(reg_evts);
+
+	return err;
+}
+
+static struct sse_event *sse_event_alloc(u32 evt, u32 priority,
+					 sse_event_handler *handler, void *arg)
+{
+	int err;
+	struct sse_event *event;
+
+	event = kzalloc(sizeof(*event), GFP_KERNEL);
+	if (!event)
+		return ERR_PTR(-ENOMEM);
+
+	event->evt_id = evt;
+	event->priority = priority;
+	event->handler_arg = arg;
+	event->handler = handler;
+
+	if (sse_event_is_global(evt))
+		err = sse_event_alloc_global(event);
+	else
+		err = sse_event_alloc_local(event);
+
+	if (err) {
+		kfree(event);
+		return ERR_PTR(err);
+	}
+
+	return event;
+}
+
+static int sse_sbi_register_event(struct sse_event *event,
+				  struct sse_registered_event *reg_evt)
+{
+	int ret;
+
+	ret = sse_event_attr_set_nolock(reg_evt, SBI_SSE_ATTR_PRIO,
+					event->priority);
+	if (ret)
+		return ret;
+
+	return arch_sse_register_event(&reg_evt->arch);
+}
+
+static int sse_event_register_local(struct sse_event *event)
+{
+	int ret;
+	struct sse_registered_event *reg_evt;
+
+	reg_evt = per_cpu_ptr(event->local, smp_processor_id());
+	ret = sse_sbi_register_event(event, reg_evt);
+	if (ret)
+		pr_debug("Failed to register event %x: err %d\n", event->evt_id,
+			 ret);
+
+	return ret;
+}
+
+static int sse_sbi_unregister_event(struct sse_event *event)
+{
+	return sse_sbi_event_func(event, SBI_SSE_EVENT_UNREGISTER);
+}
+
+struct sse_per_cpu_evt {
+	struct sse_event *event;
+	unsigned long func;
+	cpumask_t error;
+};
+
+static void sse_event_per_cpu_func(void *info)
+{
+	int ret;
+	struct sse_per_cpu_evt *cpu_evt = info;
+
+	if (cpu_evt->func == SBI_SSE_EVENT_REGISTER)
+		ret = sse_event_register_local(cpu_evt->event);
+	else
+		ret = sse_sbi_event_func(cpu_evt->event, cpu_evt->func);
+
+	if (ret)
+		cpumask_set_cpu(smp_processor_id(), &cpu_evt->error);
+}
+
+static void sse_event_free(struct sse_event *event)
+{
+	unsigned int cpu;
+	struct sse_registered_event *reg_evt;
+
+	if (sse_event_is_global(event->evt_id)) {
+		sse_event_free_registered(event->global);
+		kfree(event->global);
+	} else {
+		for_each_possible_cpu(cpu) {
+			reg_evt = per_cpu_ptr(event->local, cpu);
+			sse_event_free_registered(reg_evt);
+		}
+		free_percpu(event->local);
+	}
+
+	kfree(event);
+}
+
+static void sse_on_each_cpu(struct sse_event *event, unsigned long func,
+			    unsigned long revert_func)
+{
+	struct sse_per_cpu_evt cpu_evt;
+
+	cpu_evt.event = event;
+	cpumask_clear(&cpu_evt.error);
+	cpu_evt.func = func;
+	on_each_cpu(sse_event_per_cpu_func, &cpu_evt, 1);
+	/*
+	 * If there are some error reported by CPUs, revert event state on the
+	 * other ones
+	 */
+	if (!cpumask_empty(&cpu_evt.error)) {
+		cpumask_t revert;
+
+		cpumask_andnot(&revert, cpu_online_mask, &cpu_evt.error);
+		cpu_evt.func = revert_func;
+		on_each_cpu_mask(&revert, sse_event_per_cpu_func, &cpu_evt, 1);
+	}
+}
+
+int sse_event_enable(struct sse_event *event)
+{
+	int ret = 0;
+
+	scoped_guard(mutex, &sse_mutex) {
+		scoped_guard(cpus_read_lock) {
+			if (sse_event_is_global(event->evt_id)) {
+				ret = sse_event_enable_local(event);
+			} else {
+				sse_on_each_cpu(event, SBI_SSE_EVENT_ENABLE,
+						SBI_SSE_EVENT_DISABLE);
+			}
+		}
+	}
+	return ret;
+}
+EXPORT_SYMBOL_GPL(sse_event_enable);
+
+static int sse_events_mask(void)
+{
+	struct sbiret ret;
+
+	ret = sbi_ecall(SBI_EXT_SSE, SBI_SSE_EVENT_HART_MASK, 0, 0, 0, 0, 0, 0);
+
+	return sbi_err_map_linux_errno(ret.error);
+}
+
+static int sse_events_unmask(void)
+{
+	struct sbiret ret;
+
+	ret = sbi_ecall(SBI_EXT_SSE, SBI_SSE_EVENT_HART_UNMASK, 0, 0, 0, 0, 0, 0);
+
+	return sbi_err_map_linux_errno(ret.error);
+}
+
+static void sse_event_disable_nolock(struct sse_event *event)
+{
+	struct sse_per_cpu_evt cpu_evt;
+
+	if (sse_event_is_global(event->evt_id)) {
+		sse_event_disable_local(event);
+	} else {
+		cpu_evt.event = event;
+		cpu_evt.func = SBI_SSE_EVENT_DISABLE;
+		on_each_cpu(sse_event_per_cpu_func, &cpu_evt, 1);
+	}
+}
+
+void sse_event_disable(struct sse_event *event)
+{
+	scoped_guard(mutex, &sse_mutex) {
+		scoped_guard(cpus_read_lock) {
+			sse_event_disable_nolock(event);
+		}
+	}
+}
+EXPORT_SYMBOL_GPL(sse_event_disable);
+
+struct sse_event *sse_event_register(u32 evt, u32 priority,
+				     sse_event_handler *handler, void *arg)
+{
+	struct sse_event *event;
+	int cpu;
+	int ret = 0;
+
+	if (!sse_available)
+		return ERR_PTR(-EOPNOTSUPP);
+
+	guard(mutex)(&sse_mutex);
+	if (sse_event_get(evt))
+		return ERR_PTR(-EEXIST);
+
+	event = sse_event_alloc(evt, priority, handler, arg);
+	if (IS_ERR(event))
+		return event;
+
+	scoped_guard(cpus_read_lock) {
+		if (sse_event_is_global(evt)) {
+			unsigned long preferred_hart;
+
+			ret = sse_event_attr_get_no_lock(event->global,
+							SBI_SSE_ATTR_PREFERRED_HART,
+							&preferred_hart);
+			if (ret)
+				goto err_event_free;
+
+			cpu = riscv_hartid_to_cpuid(preferred_hart);
+			sse_global_event_update_cpu(event, cpu);
+
+			ret = sse_sbi_register_event(event, event->global);
+			if (ret)
+				goto err_event_free;
+
+		} else {
+			sse_on_each_cpu(event, SBI_SSE_EVENT_REGISTER,
+					SBI_SSE_EVENT_DISABLE);
+		}
+	}
+
+	scoped_guard(spinlock, &events_list_lock)
+		list_add(&event->list, &events);
+
+	return event;
+
+err_event_free:
+	sse_event_free(event);
+
+	return ERR_PTR(ret);
+}
+EXPORT_SYMBOL_GPL(sse_event_register);
+
+static void sse_event_unregister_nolock(struct sse_event *event)
+{
+	struct sse_per_cpu_evt cpu_evt;
+
+	if (sse_event_is_global(event->evt_id)) {
+		sse_sbi_unregister_event(event);
+	} else {
+		cpu_evt.event = event;
+		cpu_evt.func = SBI_SSE_EVENT_UNREGISTER;
+		on_each_cpu(sse_event_per_cpu_func, &cpu_evt, 1);
+	}
+}
+
+void sse_event_unregister(struct sse_event *event)
+{
+	scoped_guard(mutex, &sse_mutex) {
+		scoped_guard(cpus_read_lock)
+			sse_event_unregister_nolock(event);
+
+		scoped_guard(spinlock, &events_list_lock)
+			list_del(&event->list);
+
+		sse_event_free(event);
+	}
+}
+EXPORT_SYMBOL_GPL(sse_event_unregister);
+
+static int sse_cpu_online(unsigned int cpu)
+{
+	struct sse_event *event;
+
+	scoped_guard(spinlock, &events_list_lock) {
+		list_for_each_entry(event, &events, list) {
+			if (sse_event_is_global(event->evt_id))
+				continue;
+
+			sse_event_register_local(event);
+			if (sse_get_reg_evt(event))
+				sse_event_enable_local(event);
+		}
+	}
+
+	/* Ready to handle events. Unmask SSE. */
+	return sse_events_unmask();
+}
+
+static int sse_cpu_teardown(unsigned int cpu)
+{
+	int ret = 0;
+	unsigned int next_cpu;
+	struct sse_event *event;
+
+	/* Mask the sse events */
+	ret = sse_events_mask();
+	if (ret)
+		return ret;
+
+	scoped_guard(spinlock, &events_list_lock) {
+		list_for_each_entry(event, &events, list) {
+			if (!sse_event_is_global(event->evt_id)) {
+				if (event->global->is_enabled)
+					sse_event_disable_local(event);
+
+				sse_sbi_unregister_event(event);
+				continue;
+			}
+
+			if (event->cpu != smp_processor_id())
+				continue;
+
+			/* Update destination hart for global event */
+			next_cpu = cpumask_any_but(cpu_online_mask, cpu);
+			ret = sse_event_set_target_cpu_nolock(event, next_cpu);
+		}
+	}
+
+	return ret;
+}
+
+static void sse_reset(void)
+{
+	struct sse_event *event;
+
+	list_for_each_entry(event, &events, list) {
+		sse_event_disable_nolock(event);
+		sse_event_unregister_nolock(event);
+	}
+}
+
+static int sse_pm_notifier(struct notifier_block *nb, unsigned long action,
+			   void *data)
+{
+	WARN_ON_ONCE(preemptible());
+
+	switch (action) {
+	case CPU_PM_ENTER:
+		sse_events_mask();
+		break;
+	case CPU_PM_EXIT:
+	case CPU_PM_ENTER_FAILED:
+		sse_events_unmask();
+		break;
+	default:
+		return NOTIFY_DONE;
+	}
+
+	return NOTIFY_OK;
+}
+
+static struct notifier_block sse_pm_nb = {
+	.notifier_call = sse_pm_notifier,
+};
+
+/*
+ * Mask all CPUs and unregister all events on panic, reboot or kexec.
+ */
+static int sse_reboot_notifier(struct notifier_block *nb, unsigned long action,
+			       void *data)
+{
+	cpuhp_remove_state(sse_hp_state);
+	sse_reset();
+
+	return NOTIFY_OK;
+}
+
+static struct notifier_block sse_reboot_nb = {
+	.notifier_call = sse_reboot_notifier,
+};
+
+static int __init sse_init(void)
+{
+	int ret;
+
+	if (sbi_probe_extension(SBI_EXT_SSE) <= 0) {
+		pr_err("Missing SBI SSE extension\n");
+		return -EOPNOTSUPP;
+	}
+	pr_info("SBI SSE extension detected\n");
+
+	ret = cpu_pm_register_notifier(&sse_pm_nb);
+	if (ret) {
+		pr_warn("Failed to register CPU PM notifier...\n");
+		return ret;
+	}
+
+	ret = register_reboot_notifier(&sse_reboot_nb);
+	if (ret) {
+		pr_warn("Failed to register reboot notifier...\n");
+		goto remove_cpupm;
+	}
+
+	ret = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "riscv/sse:online",
+				sse_cpu_online, sse_cpu_teardown);
+	if (ret < 0)
+		goto remove_reboot;
+
+	sse_hp_state = ret;
+	sse_available = true;
+
+	return 0;
+
+remove_reboot:
+	unregister_reboot_notifier(&sse_reboot_nb);
+
+remove_cpupm:
+	cpu_pm_unregister_notifier(&sse_pm_nb);
+
+	return ret;
+}
+arch_initcall(sse_init);
diff --git a/include/linux/riscv_sse.h b/include/linux/riscv_sse.h
new file mode 100644
index 000000000000..d7bd0e22a00f
--- /dev/null
+++ b/include/linux/riscv_sse.h
@@ -0,0 +1,56 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright (C) 2024 Rivos Inc.
+ */
+
+#ifndef __LINUX_RISCV_SSE_H
+#define __LINUX_RISCV_SSE_H
+
+#include <linux/types.h>
+#include <linux/linkage.h>
+
+struct sse_event;
+struct pt_regs;
+
+typedef int (sse_event_handler)(u32 event_num, void *arg, struct pt_regs *regs);
+
+#ifdef CONFIG_RISCV_SSE
+
+struct sse_event *sse_event_register(u32 event_num, u32 priority,
+				     sse_event_handler *handler, void *arg);
+
+void sse_event_unregister(struct sse_event *evt);
+
+int sse_event_set_target_cpu(struct sse_event *sse_evt, unsigned int cpu);
+
+int sse_event_enable(struct sse_event *sse_evt);
+
+void sse_event_disable(struct sse_event *sse_evt);
+
+int sse_event_enable_local(struct sse_event *sse_evt);
+int sse_event_disable_local(struct sse_event *sse_evt);
+
+#else
+static inline struct sse_event *sse_event_register(u32 event_num, u32 priority,
+						   sse_event_handler *handler,
+						   void *arg)
+{
+	return ERR_PTR(-EOPNOTSUPP);
+}
+
+static inline void sse_event_unregister(struct sse_event *evt) {}
+
+static inline int sse_event_set_target_cpu(struct sse_event *sse_evt,
+					   unsigned int cpu)
+{
+	return -EOPNOTSUPP;
+}
+
+static inline int sse_event_enable(struct sse_event *sse_evt)
+{
+	return -EOPNOTSUPP;
+}
+
+static inline void sse_event_disable(struct sse_event *sse_evt) {}
+#endif
+#endif /* __LINUX_RISCV_SSE_H */
-- 
2.43.0

Re: [PATCH v6 3/5] drivers: firmware: add riscv SSE support

Posted by Alexandre Ghiti 5 months, 4 weeks ago

On 8/8/25 17:38, Clément Léger wrote:
> Add driver level interface to use RISC-V SSE arch support. This interface
> allows registering SSE handlers, and receive them. This will be used by
> PMU and GHES driver.
>
> Signed-off-by: Himanshu Chauhan <hchauhan@ventanamicro.com>
> Co-developed-by: Himanshu Chauhan <hchauhan@ventanamicro.com>


Here you need to switch the Signed-off-by and the Co-developed-by


> Signed-off-by: Clément Léger <cleger@rivosinc.com>
> Acked-by: Conor Dooley <conor.dooley@microchip.com>
> ---
>   MAINTAINERS                        |  15 +
>   drivers/firmware/Kconfig           |   1 +
>   drivers/firmware/Makefile          |   1 +
>   drivers/firmware/riscv/Kconfig     |  15 +
>   drivers/firmware/riscv/Makefile    |   3 +
>   drivers/firmware/riscv/riscv_sse.c | 694 +++++++++++++++++++++++++++++
>   include/linux/riscv_sse.h          |  56 +++
>   7 files changed, 785 insertions(+)
>   create mode 100644 drivers/firmware/riscv/Kconfig
>   create mode 100644 drivers/firmware/riscv/Makefile
>   create mode 100644 drivers/firmware/riscv/riscv_sse.c
>   create mode 100644 include/linux/riscv_sse.h
>
> diff --git a/MAINTAINERS b/MAINTAINERS
> index bd62ad58a47f..114396d47f76 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -21640,6 +21640,13 @@ T:	git git://git.kernel.org/pub/scm/linux/kernel/git/iommu/linux.git
>   F:	Documentation/devicetree/bindings/iommu/riscv,iommu.yaml
>   F:	drivers/iommu/riscv/
>   
> +RISC-V FIRMWARE DRIVERS
> +M:	Conor Dooley <conor@kernel.org>
> +L:	linux-riscv@lists.infradead.org
> +S:	Maintained
> +T:	git git://git.kernel.org/pub/scm/linux/kernel/git/conor/linux.git
> +F:	drivers/firmware/riscv/*
> +
>   RISC-V MICROCHIP FPGA SUPPORT
>   M:	Conor Dooley <conor.dooley@microchip.com>
>   M:	Daire McNamara <daire.mcnamara@microchip.com>
> @@ -21704,6 +21711,14 @@ F:	arch/riscv/boot/dts/spacemit/
>   N:	spacemit
>   K:	spacemit
>   
> +RISC-V SSE DRIVER
> +M:	Clément Léger <cleger@rivosinc.com>
> +R:	Himanshu Chauhan <himanshu@thechauhan.dev>
> +L:	linux-riscv@lists.infradead.org
> +S:	Maintained
> +F:	drivers/firmware/riscv/riscv_sse.c
> +F:	include/linux/riscv_sse.h
> +
>   RISC-V THEAD SoC SUPPORT
>   M:	Drew Fustini <fustini@kernel.org>
>   M:	Guo Ren <guoren@kernel.org>
> diff --git a/drivers/firmware/Kconfig b/drivers/firmware/Kconfig
> index bbd2155d8483..1894df87b08e 100644
> --- a/drivers/firmware/Kconfig
> +++ b/drivers/firmware/Kconfig
> @@ -294,6 +294,7 @@ source "drivers/firmware/meson/Kconfig"
>   source "drivers/firmware/microchip/Kconfig"
>   source "drivers/firmware/psci/Kconfig"
>   source "drivers/firmware/qcom/Kconfig"
> +source "drivers/firmware/riscv/Kconfig"
>   source "drivers/firmware/samsung/Kconfig"
>   source "drivers/firmware/smccc/Kconfig"
>   source "drivers/firmware/tegra/Kconfig"
> diff --git a/drivers/firmware/Makefile b/drivers/firmware/Makefile
> index 4ddec2820c96..6cdd84570ea7 100644
> --- a/drivers/firmware/Makefile
> +++ b/drivers/firmware/Makefile
> @@ -34,6 +34,7 @@ obj-y				+= efi/
>   obj-y				+= imx/
>   obj-y				+= psci/
>   obj-y				+= qcom/
> +obj-y				+= riscv/
>   obj-y				+= samsung/
>   obj-y				+= smccc/
>   obj-y				+= tegra/
> diff --git a/drivers/firmware/riscv/Kconfig b/drivers/firmware/riscv/Kconfig
> new file mode 100644
> index 000000000000..8056ed3262d9
> --- /dev/null
> +++ b/drivers/firmware/riscv/Kconfig
> @@ -0,0 +1,15 @@
> +# SPDX-License-Identifier: GPL-2.0-only
> +menu "Risc-V Specific firmware drivers"
> +depends on RISCV
> +
> +config RISCV_SSE
> +	bool "Enable SBI Supervisor Software Events support"
> +	depends on RISCV_SBI
> +	default y
> +	help
> +	  The Supervisor Software Events support allow the SBI to deliver


s/allow/allows


> +	  NMI-like notifications to the supervisor mode software. When enable,


s/enable/enabled


> +	  this option provides support to register callbacks on specific SSE
> +	  events.
> +
> +endmenu


I think RISCV_SBI_SSE would be more accurate. Why do we need to gate SSE 
support behind this config though? I don't see similar configs for other 
SBI extensions.


> diff --git a/drivers/firmware/riscv/Makefile b/drivers/firmware/riscv/Makefile
> new file mode 100644
> index 000000000000..4ccfcbbc28ea
> --- /dev/null
> +++ b/drivers/firmware/riscv/Makefile
> @@ -0,0 +1,3 @@
> +# SPDX-License-Identifier: GPL-2.0
> +
> +obj-$(CONFIG_RISCV_SSE)		+= riscv_sse.o
> diff --git a/drivers/firmware/riscv/riscv_sse.c b/drivers/firmware/riscv/riscv_sse.c
> new file mode 100644
> index 000000000000..edd107ade94a
> --- /dev/null
> +++ b/drivers/firmware/riscv/riscv_sse.c
> @@ -0,0 +1,694 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +/*
> + * Copyright (C) 2024 Rivos Inc.
> + */
> +
> +#define pr_fmt(fmt) "sse: " fmt
> +
> +#include <linux/cpu.h>
> +#include <linux/cpuhotplug.h>
> +#include <linux/cpu_pm.h>
> +#include <linux/hardirq.h>
> +#include <linux/list.h>
> +#include <linux/percpu-defs.h>
> +#include <linux/reboot.h>
> +#include <linux/riscv_sse.h>
> +#include <linux/slab.h>
> +
> +#include <asm/sbi.h>
> +#include <asm/sse.h>
> +
> +struct sse_event {
> +	struct list_head list;
> +	u32 evt_id;
> +	u32 priority;
> +	sse_event_handler *handler;
> +	void *handler_arg;
> +	/* Only valid for global events */
> +	unsigned int cpu;


Nit: Replace unsigned int with u32 to match evt_id and priority 
definition? I have noticed a mix of "unsigned int" and u32 also below, 
maybe stick to one? Same for other types.


> +
> +	union {
> +		struct sse_registered_event *global;
> +		struct sse_registered_event __percpu *local;
> +	};
> +};
> +
> +static int sse_hp_state;
> +static bool sse_available __ro_after_init;
> +static DEFINE_SPINLOCK(events_list_lock);
> +static LIST_HEAD(events);
> +static DEFINE_MUTEX(sse_mutex);
> +
> +struct sse_registered_event {
> +	struct sse_event_arch_data arch;
> +	struct sse_event *event;
> +	unsigned long attr;
> +	bool is_enabled;
> +};
> +
> +void sse_handle_event(struct sse_event_arch_data *arch_event,
> +		      struct pt_regs *regs)
> +{
> +	int ret;
> +	struct sse_registered_event *reg_evt =
> +		container_of(arch_event, struct sse_registered_event, arch);
> +	struct sse_event *evt = reg_evt->event;
> +
> +	ret = evt->handler(evt->evt_id, evt->handler_arg, regs);
> +	if (ret)
> +		pr_warn("event %x handler failed with error %d\n", evt->evt_id, ret);
> +}
> +
> +static struct sse_event *sse_event_get(u32 evt)
> +{
> +	struct sse_event *event = NULL;


No need to initialize to NULL


> +
> +	scoped_guard(spinlock, &events_list_lock) {
> +		list_for_each_entry(event, &events, list) {
> +			if (event->evt_id == evt)
> +				return event;
> +		}
> +	}
> +
> +	return NULL;
> +}
> +
> +static phys_addr_t sse_event_get_attr_phys(struct sse_registered_event *reg_evt)
> +{
> +	phys_addr_t phys;
> +	void *addr = &reg_evt->attr;
> +
> +	if (sse_event_is_global(reg_evt->event->evt_id))
> +		phys = virt_to_phys(addr);
> +	else
> +		phys = per_cpu_ptr_to_phys(addr);
> +
> +	return phys;
> +}
> +
> +static struct sse_registered_event *sse_get_reg_evt(struct sse_event *event)
> +{
> +	if (sse_event_is_global(event->evt_id))
> +		return event->global;
> +	else
> +		return per_cpu_ptr(event->local, smp_processor_id());
> +}
> +
> +static int sse_sbi_event_func(struct sse_event *event, unsigned long func)
> +{
> +	struct sbiret ret;
> +	u32 evt = event->evt_id;
> +	struct sse_registered_event *reg_evt = sse_get_reg_evt(event);
> +
> +	ret = sbi_ecall(SBI_EXT_SSE, func, evt, 0, 0, 0, 0, 0);
> +	if (ret.error) {
> +		pr_warn("Failed to execute func %lx, event %x, error %ld\n",
> +			func, evt, ret.error);
> +		return sbi_err_map_linux_errno(ret.error);
> +	}
> +
> +	if (func == SBI_SSE_EVENT_DISABLE)
> +		reg_evt->is_enabled = false;
> +	else if (func == SBI_SSE_EVENT_ENABLE)
> +		reg_evt->is_enabled = true;
> +
> +	return 0;
> +}
> +
> +int sse_event_disable_local(struct sse_event *event)
> +{
> +	return sse_sbi_event_func(event, SBI_SSE_EVENT_DISABLE);
> +}
> +EXPORT_SYMBOL_GPL(sse_event_disable_local);
> +
> +int sse_event_enable_local(struct sse_event *event)
> +{
> +	return sse_sbi_event_func(event, SBI_SSE_EVENT_ENABLE);
> +}
> +EXPORT_SYMBOL_GPL(sse_event_enable_local);
> +
> +static int sse_event_attr_get_no_lock(struct sse_registered_event *reg_evt,
> +				      unsigned long attr_id, unsigned long *val)
> +{
> +	struct sbiret sret;
> +	u32 evt = reg_evt->event->evt_id;
> +	unsigned long phys;
> +
> +	phys = sse_event_get_attr_phys(reg_evt);
> +
> +	sret = sbi_ecall(SBI_EXT_SSE, SBI_SSE_EVENT_ATTR_READ, evt, attr_id, 1,
> +			 phys, 0, 0);
> +	if (sret.error) {
> +		pr_debug("Failed to get event %x attr %lx, error %ld\n", evt,
> +			 attr_id, sret.error);
> +		return sbi_err_map_linux_errno(sret.error);
> +	}
> +
> +	*val = reg_evt->attr;
> +
> +	return 0;
> +}
> +
> +static int sse_event_attr_set_nolock(struct sse_registered_event *reg_evt,
> +				     unsigned long attr_id, unsigned long val)


Nit but here you use "nolock" and for the getter above, you use 
"no_lock" (and while scrolling I noticed "nolock" again in 
sse_event_set_target_cpu_nolock()).


> +{
> +	struct sbiret sret;
> +	u32 evt = reg_evt->event->evt_id;
> +	unsigned long phys;
> +
> +	reg_evt->attr = val;
> +	phys = sse_event_get_attr_phys(reg_evt);
> +
> +	sret = sbi_ecall(SBI_EXT_SSE, SBI_SSE_EVENT_ATTR_WRITE, evt, attr_id, 1,
> +			 phys, 0, 0);
> +	if (sret.error)
> +		pr_debug("Failed to set event %x attr %lx, error %ld\n", evt,
> +			 attr_id, sret.error);
> +
> +	return sbi_err_map_linux_errno(sret.error);
> +}
> +
> +static void sse_global_event_update_cpu(struct sse_event *event,
> +					unsigned int cpu)
> +{
> +	struct sse_registered_event *reg_evt = event->global;
> +
> +	event->cpu = cpu;
> +	arch_sse_event_update_cpu(&reg_evt->arch, cpu);
> +}
> +
> +static int sse_event_set_target_cpu_nolock(struct sse_event *event,
> +					   unsigned int cpu)
> +{
> +	unsigned int hart_id = cpuid_to_hartid_map(cpu);
> +	struct sse_registered_event *reg_evt = event->global;
> +	u32 evt = event->evt_id;
> +	bool was_enabled;
> +	int ret;
> +
> +	if (!sse_event_is_global(evt))
> +		return -EINVAL;
> +
> +	was_enabled = reg_evt->is_enabled;
> +	if (was_enabled)
> +		sse_event_disable_local(event);
> +
> +	ret = sse_event_attr_set_nolock(reg_evt, SBI_SSE_ATTR_PREFERRED_HART,
> +					hart_id);
> +	if (ret == 0)
> +		sse_global_event_update_cpu(event, cpu);
> +
> +	if (was_enabled)
> +		sse_event_enable_local(event);
> +
> +	return 0;
> +}
> +
> +int sse_event_set_target_cpu(struct sse_event *event, unsigned int cpu)
> +{
> +	int ret;
> +
> +	scoped_guard(mutex, &sse_mutex) {
> +		scoped_guard(cpus_read_lock) {
> +			if (!cpu_online(cpu))
> +				return -EINVAL;
> +
> +			ret = sse_event_set_target_cpu_nolock(event, cpu);
> +		}
> +	}
> +
> +	return ret;
> +}
> +EXPORT_SYMBOL_GPL(sse_event_set_target_cpu);
> +
> +static int sse_event_init_registered(unsigned int cpu,
> +				     struct sse_registered_event *reg_evt,
> +				     struct sse_event *event)
> +{
> +	reg_evt->event = event;
> +
> +	return arch_sse_init_event(&reg_evt->arch, event->evt_id, cpu);
> +}
> +
> +static void sse_event_free_registered(struct sse_registered_event *reg_evt)
> +{
> +	arch_sse_free_event(&reg_evt->arch);
> +}
> +
> +static int sse_event_alloc_global(struct sse_event *event)
> +{
> +	int err;
> +	struct sse_registered_event *reg_evt;
> +
> +	reg_evt = kzalloc(sizeof(*reg_evt), GFP_KERNEL);
> +	if (!reg_evt)
> +		return -ENOMEM;
> +
> +	event->global = reg_evt;
> +	err = sse_event_init_registered(smp_processor_id(), reg_evt, event);
> +	if (err)
> +		kfree(reg_evt);
> +
> +	return err;
> +}
> +
> +static int sse_event_alloc_local(struct sse_event *event)
> +{
> +	int err;
> +	unsigned int cpu, err_cpu;
> +	struct sse_registered_event *reg_evt;
> +	struct sse_registered_event __percpu *reg_evts;
> +
> +	reg_evts = alloc_percpu(struct sse_registered_event);
> +	if (!reg_evts)
> +		return -ENOMEM;
> +
> +	event->local = reg_evts;
> +
> +	for_each_possible_cpu(cpu) {
> +		reg_evt = per_cpu_ptr(reg_evts, cpu);
> +		err = sse_event_init_registered(cpu, reg_evt, event);
> +		if (err) {
> +			err_cpu = cpu;
> +			goto err_free_per_cpu;
> +		}
> +	}
> +
> +	return 0;
> +
> +err_free_per_cpu:
> +	for_each_possible_cpu(cpu) {
> +		if (cpu == err_cpu)
> +			break;
> +		reg_evt = per_cpu_ptr(reg_evts, cpu);
> +		sse_event_free_registered(reg_evt);
> +	}
> +
> +	free_percpu(reg_evts);
> +
> +	return err;
> +}
> +
> +static struct sse_event *sse_event_alloc(u32 evt, u32 priority,
> +					 sse_event_handler *handler, void *arg)
> +{
> +	int err;
> +	struct sse_event *event;
> +
> +	event = kzalloc(sizeof(*event), GFP_KERNEL);
> +	if (!event)
> +		return ERR_PTR(-ENOMEM);
> +
> +	event->evt_id = evt;
> +	event->priority = priority;
> +	event->handler_arg = arg;
> +	event->handler = handler;
> +
> +	if (sse_event_is_global(evt))
> +		err = sse_event_alloc_global(event);
> +	else
> +		err = sse_event_alloc_local(event);
> +
> +	if (err) {
> +		kfree(event);
> +		return ERR_PTR(err);
> +	}
> +
> +	return event;
> +}
> +
> +static int sse_sbi_register_event(struct sse_event *event,
> +				  struct sse_registered_event *reg_evt)
> +{
> +	int ret;
> +
> +	ret = sse_event_attr_set_nolock(reg_evt, SBI_SSE_ATTR_PRIO,
> +					event->priority);
> +	if (ret)
> +		return ret;
> +
> +	return arch_sse_register_event(&reg_evt->arch);
> +}
> +
> +static int sse_event_register_local(struct sse_event *event)
> +{
> +	int ret;
> +	struct sse_registered_event *reg_evt;
> +
> +	reg_evt = per_cpu_ptr(event->local, smp_processor_id());
> +	ret = sse_sbi_register_event(event, reg_evt);
> +	if (ret)
> +		pr_debug("Failed to register event %x: err %d\n", event->evt_id,
> +			 ret);
> +
> +	return ret;
> +}
> +
> +static int sse_sbi_unregister_event(struct sse_event *event)
> +{
> +	return sse_sbi_event_func(event, SBI_SSE_EVENT_UNREGISTER);
> +}
> +
> +struct sse_per_cpu_evt {
> +	struct sse_event *event;
> +	unsigned long func;
> +	cpumask_t error;
> +};
> +
> +static void sse_event_per_cpu_func(void *info)
> +{
> +	int ret;
> +	struct sse_per_cpu_evt *cpu_evt = info;
> +
> +	if (cpu_evt->func == SBI_SSE_EVENT_REGISTER)
> +		ret = sse_event_register_local(cpu_evt->event);
> +	else
> +		ret = sse_sbi_event_func(cpu_evt->event, cpu_evt->func);
> +
> +	if (ret)
> +		cpumask_set_cpu(smp_processor_id(), &cpu_evt->error);
> +}
> +
> +static void sse_event_free(struct sse_event *event)
> +{
> +	unsigned int cpu;
> +	struct sse_registered_event *reg_evt;
> +
> +	if (sse_event_is_global(event->evt_id)) {
> +		sse_event_free_registered(event->global);
> +		kfree(event->global);
> +	} else {
> +		for_each_possible_cpu(cpu) {
> +			reg_evt = per_cpu_ptr(event->local, cpu);
> +			sse_event_free_registered(reg_evt);
> +		}
> +		free_percpu(event->local);
> +	}
> +
> +	kfree(event);
> +}
> +
> +static void sse_on_each_cpu(struct sse_event *event, unsigned long func,
> +			    unsigned long revert_func)
> +{
> +	struct sse_per_cpu_evt cpu_evt;
> +
> +	cpu_evt.event = event;
> +	cpumask_clear(&cpu_evt.error);
> +	cpu_evt.func = func;
> +	on_each_cpu(sse_event_per_cpu_func, &cpu_evt, 1);
> +	/*
> +	 * If there are some error reported by CPUs, revert event state on the
> +	 * other ones
> +	 */
> +	if (!cpumask_empty(&cpu_evt.error)) {
> +		cpumask_t revert;
> +
> +		cpumask_andnot(&revert, cpu_online_mask, &cpu_evt.error);
> +		cpu_evt.func = revert_func;
> +		on_each_cpu_mask(&revert, sse_event_per_cpu_func, &cpu_evt, 1);
> +	}
> +}
> +
> +int sse_event_enable(struct sse_event *event)
> +{
> +	int ret = 0;
> +
> +	scoped_guard(mutex, &sse_mutex) {
> +		scoped_guard(cpus_read_lock) {
> +			if (sse_event_is_global(event->evt_id)) {
> +				ret = sse_event_enable_local(event);
> +			} else {
> +				sse_on_each_cpu(event, SBI_SSE_EVENT_ENABLE,
> +						SBI_SSE_EVENT_DISABLE);
> +			}
> +		}
> +	}
> +	return ret;
> +}
> +EXPORT_SYMBOL_GPL(sse_event_enable);
> +
> +static int sse_events_mask(void)
> +{
> +	struct sbiret ret;
> +
> +	ret = sbi_ecall(SBI_EXT_SSE, SBI_SSE_EVENT_HART_MASK, 0, 0, 0, 0, 0, 0);
> +
> +	return sbi_err_map_linux_errno(ret.error);
> +}
> +
> +static int sse_events_unmask(void)
> +{
> +	struct sbiret ret;
> +
> +	ret = sbi_ecall(SBI_EXT_SSE, SBI_SSE_EVENT_HART_UNMASK, 0, 0, 0, 0, 0, 0);
> +
> +	return sbi_err_map_linux_errno(ret.error);
> +}
> +
> +static void sse_event_disable_nolock(struct sse_event *event)
> +{
> +	struct sse_per_cpu_evt cpu_evt;
> +
> +	if (sse_event_is_global(event->evt_id)) {
> +		sse_event_disable_local(event);
> +	} else {
> +		cpu_evt.event = event;
> +		cpu_evt.func = SBI_SSE_EVENT_DISABLE;
> +		on_each_cpu(sse_event_per_cpu_func, &cpu_evt, 1);
> +	}
> +}
> +
> +void sse_event_disable(struct sse_event *event)
> +{
> +	scoped_guard(mutex, &sse_mutex) {
> +		scoped_guard(cpus_read_lock) {
> +			sse_event_disable_nolock(event);
> +		}
> +	}
> +}
> +EXPORT_SYMBOL_GPL(sse_event_disable);
> +
> +struct sse_event *sse_event_register(u32 evt, u32 priority,
> +				     sse_event_handler *handler, void *arg)
> +{
> +	struct sse_event *event;
> +	int cpu;
> +	int ret = 0;
> +
> +	if (!sse_available)
> +		return ERR_PTR(-EOPNOTSUPP);
> +
> +	guard(mutex)(&sse_mutex);
> +	if (sse_event_get(evt))
> +		return ERR_PTR(-EEXIST);
> +
> +	event = sse_event_alloc(evt, priority, handler, arg);
> +	if (IS_ERR(event))
> +		return event;
> +
> +	scoped_guard(cpus_read_lock) {
> +		if (sse_event_is_global(evt)) {
> +			unsigned long preferred_hart;
> +
> +			ret = sse_event_attr_get_no_lock(event->global,
> +							SBI_SSE_ATTR_PREFERRED_HART,
> +							&preferred_hart);
> +			if (ret)
> +				goto err_event_free;
> +
> +			cpu = riscv_hartid_to_cpuid(preferred_hart);
> +			sse_global_event_update_cpu(event, cpu);
> +
> +			ret = sse_sbi_register_event(event, event->global);
> +			if (ret)
> +				goto err_event_free;
> +
> +		} else {
> +			sse_on_each_cpu(event, SBI_SSE_EVENT_REGISTER,
> +					SBI_SSE_EVENT_DISABLE);
> +		}
> +	}
> +
> +	scoped_guard(spinlock, &events_list_lock)
> +		list_add(&event->list, &events);
> +
> +	return event;
> +
> +err_event_free:
> +	sse_event_free(event);
> +
> +	return ERR_PTR(ret);
> +}
> +EXPORT_SYMBOL_GPL(sse_event_register);
> +
> +static void sse_event_unregister_nolock(struct sse_event *event)
> +{
> +	struct sse_per_cpu_evt cpu_evt;
> +
> +	if (sse_event_is_global(event->evt_id)) {
> +		sse_sbi_unregister_event(event);
> +	} else {
> +		cpu_evt.event = event;
> +		cpu_evt.func = SBI_SSE_EVENT_UNREGISTER;
> +		on_each_cpu(sse_event_per_cpu_func, &cpu_evt, 1);
> +	}
> +}
> +
> +void sse_event_unregister(struct sse_event *event)
> +{
> +	scoped_guard(mutex, &sse_mutex) {
> +		scoped_guard(cpus_read_lock)
> +			sse_event_unregister_nolock(event);
> +
> +		scoped_guard(spinlock, &events_list_lock)
> +			list_del(&event->list);
> +
> +		sse_event_free(event);
> +	}
> +}
> +EXPORT_SYMBOL_GPL(sse_event_unregister);
> +
> +static int sse_cpu_online(unsigned int cpu)
> +{
> +	struct sse_event *event;
> +
> +	scoped_guard(spinlock, &events_list_lock) {
> +		list_for_each_entry(event, &events, list) {
> +			if (sse_event_is_global(event->evt_id))
> +				continue;
> +
> +			sse_event_register_local(event);
> +			if (sse_get_reg_evt(event))
> +				sse_event_enable_local(event);
> +		}
> +	}
> +
> +	/* Ready to handle events. Unmask SSE. */
> +	return sse_events_unmask();
> +}
> +
> +static int sse_cpu_teardown(unsigned int cpu)
> +{
> +	int ret = 0;
> +	unsigned int next_cpu;
> +	struct sse_event *event;
> +
> +	/* Mask the sse events */
> +	ret = sse_events_mask();
> +	if (ret)
> +		return ret;
> +
> +	scoped_guard(spinlock, &events_list_lock) {
> +		list_for_each_entry(event, &events, list) {
> +			if (!sse_event_is_global(event->evt_id)) {
> +				if (event->global->is_enabled)
> +					sse_event_disable_local(event);
> +
> +				sse_sbi_unregister_event(event);
> +				continue;
> +			}
> +
> +			if (event->cpu != smp_processor_id())
> +				continue;
> +
> +			/* Update destination hart for global event */
> +			next_cpu = cpumask_any_but(cpu_online_mask, cpu);
> +			ret = sse_event_set_target_cpu_nolock(event, next_cpu);
> +		}
> +	}
> +
> +	return ret;
> +}
> +
> +static void sse_reset(void)
> +{
> +	struct sse_event *event;
> +
> +	list_for_each_entry(event, &events, list) {
> +		sse_event_disable_nolock(event);
> +		sse_event_unregister_nolock(event);
> +	}
> +}
> +
> +static int sse_pm_notifier(struct notifier_block *nb, unsigned long action,
> +			   void *data)
> +{
> +	WARN_ON_ONCE(preemptible());
> +
> +	switch (action) {
> +	case CPU_PM_ENTER:
> +		sse_events_mask();
> +		break;
> +	case CPU_PM_EXIT:
> +	case CPU_PM_ENTER_FAILED:
> +		sse_events_unmask();
> +		break;
> +	default:
> +		return NOTIFY_DONE;
> +	}
> +
> +	return NOTIFY_OK;
> +}
> +
> +static struct notifier_block sse_pm_nb = {
> +	.notifier_call = sse_pm_notifier,
> +};
> +
> +/*
> + * Mask all CPUs and unregister all events on panic, reboot or kexec.
> + */
> +static int sse_reboot_notifier(struct notifier_block *nb, unsigned long action,
> +			       void *data)
> +{
> +	cpuhp_remove_state(sse_hp_state);
> +	sse_reset();
> +
> +	return NOTIFY_OK;
> +}
> +
> +static struct notifier_block sse_reboot_nb = {
> +	.notifier_call = sse_reboot_notifier,
> +};
> +
> +static int __init sse_init(void)
> +{
> +	int ret;
> +
> +	if (sbi_probe_extension(SBI_EXT_SSE) <= 0) {
> +		pr_err("Missing SBI SSE extension\n");
> +		return -EOPNOTSUPP;
> +	}
> +	pr_info("SBI SSE extension detected\n");
> +
> +	ret = cpu_pm_register_notifier(&sse_pm_nb);
> +	if (ret) {
> +		pr_warn("Failed to register CPU PM notifier...\n");
> +		return ret;
> +	}
> +
> +	ret = register_reboot_notifier(&sse_reboot_nb);
> +	if (ret) {
> +		pr_warn("Failed to register reboot notifier...\n");
> +		goto remove_cpupm;
> +	}
> +
> +	ret = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "riscv/sse:online",
> +				sse_cpu_online, sse_cpu_teardown);
> +	if (ret < 0)
> +		goto remove_reboot;
> +
> +	sse_hp_state = ret;
> +	sse_available = true;
> +
> +	return 0;
> +
> +remove_reboot:
> +	unregister_reboot_notifier(&sse_reboot_nb);
> +
> +remove_cpupm:
> +	cpu_pm_unregister_notifier(&sse_pm_nb);
> +
> +	return ret;
> +}
> +arch_initcall(sse_init);
> diff --git a/include/linux/riscv_sse.h b/include/linux/riscv_sse.h
> new file mode 100644
> index 000000000000..d7bd0e22a00f
> --- /dev/null
> +++ b/include/linux/riscv_sse.h
> @@ -0,0 +1,56 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +/*
> + * Copyright (C) 2024 Rivos Inc.
> + */
> +
> +#ifndef __LINUX_RISCV_SSE_H
> +#define __LINUX_RISCV_SSE_H
> +
> +#include <linux/types.h>
> +#include <linux/linkage.h>
> +
> +struct sse_event;
> +struct pt_regs;
> +
> +typedef int (sse_event_handler)(u32 event_num, void *arg, struct pt_regs *regs);


I don't see function pointer listed here 
https://www.kernel.org/doc/html/v4.10/process/coding-style.html#typedefs 
so I'd rather avoid this one.


> +
> +#ifdef CONFIG_RISCV_SSE
> +
> +struct sse_event *sse_event_register(u32 event_num, u32 priority,
> +				     sse_event_handler *handler, void *arg);
> +
> +void sse_event_unregister(struct sse_event *evt);
> +
> +int sse_event_set_target_cpu(struct sse_event *sse_evt, unsigned int cpu);
> +
> +int sse_event_enable(struct sse_event *sse_evt);
> +
> +void sse_event_disable(struct sse_event *sse_evt);
> +
> +int sse_event_enable_local(struct sse_event *sse_evt);
> +int sse_event_disable_local(struct sse_event *sse_evt);
> +
> +#else
> +static inline struct sse_event *sse_event_register(u32 event_num, u32 priority,
> +						   sse_event_handler *handler,
> +						   void *arg)
> +{
> +	return ERR_PTR(-EOPNOTSUPP);
> +}
> +
> +static inline void sse_event_unregister(struct sse_event *evt) {}
> +
> +static inline int sse_event_set_target_cpu(struct sse_event *sse_evt,
> +					   unsigned int cpu)
> +{
> +	return -EOPNOTSUPP;
> +}
> +
> +static inline int sse_event_enable(struct sse_event *sse_evt)
> +{
> +	return -EOPNOTSUPP;
> +}
> +
> +static inline void sse_event_disable(struct sse_event *sse_evt) {}
> +#endif
> +#endif /* __LINUX_RISCV_SSE_H */

Re: [PATCH v6 3/5] drivers: firmware: add riscv SSE support

Posted by Clément Léger 5 months, 2 weeks ago

Hi Alex,

On 13/08/2025 14:08, Alexandre Ghiti wrote:
> 
> On 8/8/25 17:38, Clément Léger wrote:
>> Add driver level interface to use RISC-V SSE arch support. This interface
>> allows registering SSE handlers, and receive them. This will be used by
>> PMU and GHES driver.
>>
>> Signed-off-by: Himanshu Chauhan <hchauhan@ventanamicro.com>
>> Co-developed-by: Himanshu Chauhan <hchauhan@ventanamicro.com>
> 
> 
> Here you need to switch the Signed-off-by and the Co-developed-by

Acked.
> 
> 
>> Signed-off-by: Clément Léger <cleger@rivosinc.com>
>> Acked-by: Conor Dooley <conor.dooley@microchip.com>
>> ---
>>   MAINTAINERS                        |  15 +
>>   drivers/firmware/Kconfig           |   1 +
>>   drivers/firmware/Makefile          |   1 +
>>   drivers/firmware/riscv/Kconfig     |  15 +
>>   drivers/firmware/riscv/Makefile    |   3 +
>>   drivers/firmware/riscv/riscv_sse.c | 694 +++++++++++++++++++++++++++++
>>   include/linux/riscv_sse.h          |  56 +++
>>   7 files changed, 785 insertions(+)
>>   create mode 100644 drivers/firmware/riscv/Kconfig
>>   create mode 100644 drivers/firmware/riscv/Makefile
>>   create mode 100644 drivers/firmware/riscv/riscv_sse.c
>>   create mode 100644 include/linux/riscv_sse.h
>>
>> diff --git a/MAINTAINERS b/MAINTAINERS
>> index bd62ad58a47f..114396d47f76 100644
>> --- a/MAINTAINERS
>> +++ b/MAINTAINERS
>> @@ -21640,6 +21640,13 @@ T:    git git://git.kernel.org/pub/scm/linux/
>> kernel/git/iommu/linux.git
>>   F:    Documentation/devicetree/bindings/iommu/riscv,iommu.yaml
>>   F:    drivers/iommu/riscv/
>>   +RISC-V FIRMWARE DRIVERS
>> +M:    Conor Dooley <conor@kernel.org>
>> +L:    linux-riscv@lists.infradead.org
>> +S:    Maintained
>> +T:    git git://git.kernel.org/pub/scm/linux/kernel/git/conor/linux.git
>> +F:    drivers/firmware/riscv/*
>> +
>>   RISC-V MICROCHIP FPGA SUPPORT
>>   M:    Conor Dooley <conor.dooley@microchip.com>
>>   M:    Daire McNamara <daire.mcnamara@microchip.com>
>> @@ -21704,6 +21711,14 @@ F:    arch/riscv/boot/dts/spacemit/
>>   N:    spacemit
>>   K:    spacemit
>>   +RISC-V SSE DRIVER
>> +M:    Clément Léger <cleger@rivosinc.com>
>> +R:    Himanshu Chauhan <himanshu@thechauhan.dev>
>> +L:    linux-riscv@lists.infradead.org
>> +S:    Maintained
>> +F:    drivers/firmware/riscv/riscv_sse.c
>> +F:    include/linux/riscv_sse.h
>> +
>>   RISC-V THEAD SoC SUPPORT
>>   M:    Drew Fustini <fustini@kernel.org>
>>   M:    Guo Ren <guoren@kernel.org>
>> diff --git a/drivers/firmware/Kconfig b/drivers/firmware/Kconfig
>> index bbd2155d8483..1894df87b08e 100644
>> --- a/drivers/firmware/Kconfig
>> +++ b/drivers/firmware/Kconfig
>> @@ -294,6 +294,7 @@ source "drivers/firmware/meson/Kconfig"
>>   source "drivers/firmware/microchip/Kconfig"
>>   source "drivers/firmware/psci/Kconfig"
>>   source "drivers/firmware/qcom/Kconfig"
>> +source "drivers/firmware/riscv/Kconfig"
>>   source "drivers/firmware/samsung/Kconfig"
>>   source "drivers/firmware/smccc/Kconfig"
>>   source "drivers/firmware/tegra/Kconfig"
>> diff --git a/drivers/firmware/Makefile b/drivers/firmware/Makefile
>> index 4ddec2820c96..6cdd84570ea7 100644
>> --- a/drivers/firmware/Makefile
>> +++ b/drivers/firmware/Makefile
>> @@ -34,6 +34,7 @@ obj-y                += efi/
>>   obj-y                += imx/
>>   obj-y                += psci/
>>   obj-y                += qcom/
>> +obj-y                += riscv/
>>   obj-y                += samsung/
>>   obj-y                += smccc/
>>   obj-y                += tegra/
>> diff --git a/drivers/firmware/riscv/Kconfig b/drivers/firmware/riscv/
>> Kconfig
>> new file mode 100644
>> index 000000000000..8056ed3262d9
>> --- /dev/null
>> +++ b/drivers/firmware/riscv/Kconfig
>> @@ -0,0 +1,15 @@
>> +# SPDX-License-Identifier: GPL-2.0-only
>> +menu "Risc-V Specific firmware drivers"
>> +depends on RISCV
>> +
>> +config RISCV_SSE
>> +    bool "Enable SBI Supervisor Software Events support"
>> +    depends on RISCV_SBI
>> +    default y
>> +    help
>> +      The Supervisor Software Events support allow the SBI to deliver
> 
> 
> s/allow/allows
> 
> 
>> +      NMI-like notifications to the supervisor mode software. When
>> enable,
> 
> 
> s/enable/enabled
> 
> 
>> +      this option provides support to register callbacks on specific SSE
>> +      events.
>> +
>> +endmenu
> 
> 
> I think RISCV_SBI_SSE would be more accurate. Why do we need to gate SSE
> support behind this config though? I don't see similar configs for other
> SBI extensions.

SSE is way more intrusive/larger than the other extensions in terms of
code so it made sense to have a config option for it.

> 
> 
>> diff --git a/drivers/firmware/riscv/Makefile b/drivers/firmware/riscv/
>> Makefile
>> new file mode 100644
>> index 000000000000..4ccfcbbc28ea
>> --- /dev/null
>> +++ b/drivers/firmware/riscv/Makefile
>> @@ -0,0 +1,3 @@
>> +# SPDX-License-Identifier: GPL-2.0
>> +
>> +obj-$(CONFIG_RISCV_SSE)        += riscv_sse.o
>> diff --git a/drivers/firmware/riscv/riscv_sse.c b/drivers/firmware/
>> riscv/riscv_sse.c
>> new file mode 100644
>> index 000000000000..edd107ade94a
>> --- /dev/null
>> +++ b/drivers/firmware/riscv/riscv_sse.c
>> @@ -0,0 +1,694 @@
>> +// SPDX-License-Identifier: GPL-2.0-only
>> +/*
>> + * Copyright (C) 2024 Rivos Inc.
>> + */
>> +
>> +#define pr_fmt(fmt) "sse: " fmt
>> +
>> +#include <linux/cpu.h>
>> +#include <linux/cpuhotplug.h>
>> +#include <linux/cpu_pm.h>
>> +#include <linux/hardirq.h>
>> +#include <linux/list.h>
>> +#include <linux/percpu-defs.h>
>> +#include <linux/reboot.h>
>> +#include <linux/riscv_sse.h>
>> +#include <linux/slab.h>
>> +
>> +#include <asm/sbi.h>
>> +#include <asm/sse.h>
>> +
>> +struct sse_event {
>> +    struct list_head list;
>> +    u32 evt_id;
>> +    u32 priority;
>> +    sse_event_handler *handler;
>> +    void *handler_arg;
>> +    /* Only valid for global events */
>> +    unsigned int cpu;
> 
> 
> Nit: Replace unsigned int with u32 to match evt_id and priority
> definition? I have noticed a mix of "unsigned int" and u32 also below,
> maybe stick to one? Same for other types.

The CPU is always defined as unsigned int though this file which matches
the cpu_online/cpu_offline definitions. I think keeping it like this is
fine.

> 
> 
>> +
>> +    union {
>> +        struct sse_registered_event *global;
>> +        struct sse_registered_event __percpu *local;
>> +    };
>> +};
>> +
>> +static int sse_hp_state;
>> +static bool sse_available __ro_after_init;
>> +static DEFINE_SPINLOCK(events_list_lock);
>> +static LIST_HEAD(events);
>> +static DEFINE_MUTEX(sse_mutex);
>> +
>> +struct sse_registered_event {
>> +    struct sse_event_arch_data arch;
>> +    struct sse_event *event;
>> +    unsigned long attr;
>> +    bool is_enabled;
>> +};
>> +
>> +void sse_handle_event(struct sse_event_arch_data *arch_event,
>> +              struct pt_regs *regs)
>> +{
>> +    int ret;
>> +    struct sse_registered_event *reg_evt =
>> +        container_of(arch_event, struct sse_registered_event, arch);
>> +    struct sse_event *evt = reg_evt->event;
>> +
>> +    ret = evt->handler(evt->evt_id, evt->handler_arg, regs);
>> +    if (ret)
>> +        pr_warn("event %x handler failed with error %d\n", evt-
>> >evt_id, ret);
>> +}
>> +
>> +static struct sse_event *sse_event_get(u32 evt)
>> +{
>> +    struct sse_event *event = NULL;
> 
> 
> No need to initialize to NULL
> 
> 
>> +
>> +    scoped_guard(spinlock, &events_list_lock) {
>> +        list_for_each_entry(event, &events, list) {
>> +            if (event->evt_id == evt)
>> +                return event;
>> +        }
>> +    }
>> +
>> +    return NULL;
>> +}
>> +
>> +static phys_addr_t sse_event_get_attr_phys(struct
>> sse_registered_event *reg_evt)
>> +{
>> +    phys_addr_t phys;
>> +    void *addr = &reg_evt->attr;
>> +
>> +    if (sse_event_is_global(reg_evt->event->evt_id))
>> +        phys = virt_to_phys(addr);
>> +    else
>> +        phys = per_cpu_ptr_to_phys(addr);
>> +
>> +    return phys;
>> +}
>> +
>> +static struct sse_registered_event *sse_get_reg_evt(struct sse_event
>> *event)
>> +{
>> +    if (sse_event_is_global(event->evt_id))
>> +        return event->global;
>> +    else
>> +        return per_cpu_ptr(event->local, smp_processor_id());
>> +}
>> +
>> +static int sse_sbi_event_func(struct sse_event *event, unsigned long
>> func)
>> +{
>> +    struct sbiret ret;
>> +    u32 evt = event->evt_id;
>> +    struct sse_registered_event *reg_evt = sse_get_reg_evt(event);
>> +
>> +    ret = sbi_ecall(SBI_EXT_SSE, func, evt, 0, 0, 0, 0, 0);
>> +    if (ret.error) {
>> +        pr_warn("Failed to execute func %lx, event %x, error %ld\n",
>> +            func, evt, ret.error);
>> +        return sbi_err_map_linux_errno(ret.error);
>> +    }
>> +
>> +    if (func == SBI_SSE_EVENT_DISABLE)
>> +        reg_evt->is_enabled = false;
>> +    else if (func == SBI_SSE_EVENT_ENABLE)
>> +        reg_evt->is_enabled = true;
>> +
>> +    return 0;
>> +}
>> +
>> +int sse_event_disable_local(struct sse_event *event)
>> +{
>> +    return sse_sbi_event_func(event, SBI_SSE_EVENT_DISABLE);
>> +}
>> +EXPORT_SYMBOL_GPL(sse_event_disable_local);
>> +
>> +int sse_event_enable_local(struct sse_event *event)
>> +{
>> +    return sse_sbi_event_func(event, SBI_SSE_EVENT_ENABLE);
>> +}
>> +EXPORT_SYMBOL_GPL(sse_event_enable_local);
>> +
>> +static int sse_event_attr_get_no_lock(struct sse_registered_event
>> *reg_evt,
>> +                      unsigned long attr_id, unsigned long *val)
>> +{
>> +    struct sbiret sret;
>> +    u32 evt = reg_evt->event->evt_id;
>> +    unsigned long phys;
>> +
>> +    phys = sse_event_get_attr_phys(reg_evt);
>> +
>> +    sret = sbi_ecall(SBI_EXT_SSE, SBI_SSE_EVENT_ATTR_READ, evt,
>> attr_id, 1,
>> +             phys, 0, 0);
>> +    if (sret.error) {
>> +        pr_debug("Failed to get event %x attr %lx, error %ld\n", evt,
>> +             attr_id, sret.error);
>> +        return sbi_err_map_linux_errno(sret.error);
>> +    }
>> +
>> +    *val = reg_evt->attr;
>> +
>> +    return 0;
>> +}
>> +
>> +static int sse_event_attr_set_nolock(struct sse_registered_event
>> *reg_evt,
>> +                     unsigned long attr_id, unsigned long val)
> 
> 
> Nit but here you use "nolock" and for the getter above, you use
> "no_lock" (and while scrolling I noticed "nolock" again in
> sse_event_set_target_cpu_nolock()).

Will use nolock like the other.

> 
> 
>> +{
>> +    struct sbiret sret;
>> +    u32 evt = reg_evt->event->evt_id;
>> +    unsigned long phys;
>> +
>> +    reg_evt->attr = val;
>> +    phys = sse_event_get_attr_phys(reg_evt);
>> +
>> +    sret = sbi_ecall(SBI_EXT_SSE, SBI_SSE_EVENT_ATTR_WRITE, evt,
>> attr_id, 1,
>> +             phys, 0, 0);
>> +    if (sret.error)
>> +        pr_debug("Failed to set event %x attr %lx, error %ld\n", evt,
>> +             attr_id, sret.error);
>> +
>> +    return sbi_err_map_linux_errno(sret.error);
>> +}
>> +
>> +static void sse_global_event_update_cpu(struct sse_event *event,
>> +                    unsigned int cpu)
>> +{
>> +    struct sse_registered_event *reg_evt = event->global;
>> +
>> +    event->cpu = cpu;
>> +    arch_sse_event_update_cpu(&reg_evt->arch, cpu);
>> +}
>> +
>> +static int sse_event_set_target_cpu_nolock(struct sse_event *event,
>> +                       unsigned int cpu)
>> +{
>> +    unsigned int hart_id = cpuid_to_hartid_map(cpu);
>> +    struct sse_registered_event *reg_evt = event->global;
>> +    u32 evt = event->evt_id;
>> +    bool was_enabled;
>> +    int ret;
>> +
>> +    if (!sse_event_is_global(evt))
>> +        return -EINVAL;
>> +
>> +    was_enabled = reg_evt->is_enabled;
>> +    if (was_enabled)
>> +        sse_event_disable_local(event);
>> +
>> +    ret = sse_event_attr_set_nolock(reg_evt,
>> SBI_SSE_ATTR_PREFERRED_HART,
>> +                    hart_id);
>> +    if (ret == 0)
>> +        sse_global_event_update_cpu(event, cpu);
>> +
>> +    if (was_enabled)
>> +        sse_event_enable_local(event);
>> +
>> +    return 0;
>> +}
>> +
>> +int sse_event_set_target_cpu(struct sse_event *event, unsigned int cpu)
>> +{
>> +    int ret;
>> +
>> +    scoped_guard(mutex, &sse_mutex) {
>> +        scoped_guard(cpus_read_lock) {
>> +            if (!cpu_online(cpu))
>> +                return -EINVAL;
>> +
>> +            ret = sse_event_set_target_cpu_nolock(event, cpu);
>> +        }
>> +    }
>> +
>> +    return ret;
>> +}
>> +EXPORT_SYMBOL_GPL(sse_event_set_target_cpu);
>> +
>> +static int sse_event_init_registered(unsigned int cpu,
>> +                     struct sse_registered_event *reg_evt,
>> +                     struct sse_event *event)
>> +{
>> +    reg_evt->event = event;
>> +
>> +    return arch_sse_init_event(&reg_evt->arch, event->evt_id, cpu);
>> +}
>> +
>> +static void sse_event_free_registered(struct sse_registered_event
>> *reg_evt)
>> +{
>> +    arch_sse_free_event(&reg_evt->arch);
>> +}
>> +
>> +static int sse_event_alloc_global(struct sse_event *event)
>> +{
>> +    int err;
>> +    struct sse_registered_event *reg_evt;
>> +
>> +    reg_evt = kzalloc(sizeof(*reg_evt), GFP_KERNEL);
>> +    if (!reg_evt)
>> +        return -ENOMEM;
>> +
>> +    event->global = reg_evt;
>> +    err = sse_event_init_registered(smp_processor_id(), reg_evt, event);
>> +    if (err)
>> +        kfree(reg_evt);
>> +
>> +    return err;
>> +}
>> +
>> +static int sse_event_alloc_local(struct sse_event *event)
>> +{
>> +    int err;
>> +    unsigned int cpu, err_cpu;
>> +    struct sse_registered_event *reg_evt;
>> +    struct sse_registered_event __percpu *reg_evts;
>> +
>> +    reg_evts = alloc_percpu(struct sse_registered_event);
>> +    if (!reg_evts)
>> +        return -ENOMEM;
>> +
>> +    event->local = reg_evts;
>> +
>> +    for_each_possible_cpu(cpu) {
>> +        reg_evt = per_cpu_ptr(reg_evts, cpu);
>> +        err = sse_event_init_registered(cpu, reg_evt, event);
>> +        if (err) {
>> +            err_cpu = cpu;
>> +            goto err_free_per_cpu;
>> +        }
>> +    }
>> +
>> +    return 0;
>> +
>> +err_free_per_cpu:
>> +    for_each_possible_cpu(cpu) {
>> +        if (cpu == err_cpu)
>> +            break;
>> +        reg_evt = per_cpu_ptr(reg_evts, cpu);
>> +        sse_event_free_registered(reg_evt);
>> +    }
>> +
>> +    free_percpu(reg_evts);
>> +
>> +    return err;
>> +}
>> +
>> +static struct sse_event *sse_event_alloc(u32 evt, u32 priority,
>> +                     sse_event_handler *handler, void *arg)
>> +{
>> +    int err;
>> +    struct sse_event *event;
>> +
>> +    event = kzalloc(sizeof(*event), GFP_KERNEL);
>> +    if (!event)
>> +        return ERR_PTR(-ENOMEM);
>> +
>> +    event->evt_id = evt;
>> +    event->priority = priority;
>> +    event->handler_arg = arg;
>> +    event->handler = handler;
>> +
>> +    if (sse_event_is_global(evt))
>> +        err = sse_event_alloc_global(event);
>> +    else
>> +        err = sse_event_alloc_local(event);
>> +
>> +    if (err) {
>> +        kfree(event);
>> +        return ERR_PTR(err);
>> +    }
>> +
>> +    return event;
>> +}
>> +
>> +static int sse_sbi_register_event(struct sse_event *event,
>> +                  struct sse_registered_event *reg_evt)
>> +{
>> +    int ret;
>> +
>> +    ret = sse_event_attr_set_nolock(reg_evt, SBI_SSE_ATTR_PRIO,
>> +                    event->priority);
>> +    if (ret)
>> +        return ret;
>> +
>> +    return arch_sse_register_event(&reg_evt->arch);
>> +}
>> +
>> +static int sse_event_register_local(struct sse_event *event)
>> +{
>> +    int ret;
>> +    struct sse_registered_event *reg_evt;
>> +
>> +    reg_evt = per_cpu_ptr(event->local, smp_processor_id());
>> +    ret = sse_sbi_register_event(event, reg_evt);
>> +    if (ret)
>> +        pr_debug("Failed to register event %x: err %d\n", event->evt_id,
>> +             ret);
>> +
>> +    return ret;
>> +}
>> +
>> +static int sse_sbi_unregister_event(struct sse_event *event)
>> +{
>> +    return sse_sbi_event_func(event, SBI_SSE_EVENT_UNREGISTER);
>> +}
>> +
>> +struct sse_per_cpu_evt {
>> +    struct sse_event *event;
>> +    unsigned long func;
>> +    cpumask_t error;
>> +};
>> +
>> +static void sse_event_per_cpu_func(void *info)
>> +{
>> +    int ret;
>> +    struct sse_per_cpu_evt *cpu_evt = info;
>> +
>> +    if (cpu_evt->func == SBI_SSE_EVENT_REGISTER)
>> +        ret = sse_event_register_local(cpu_evt->event);
>> +    else
>> +        ret = sse_sbi_event_func(cpu_evt->event, cpu_evt->func);
>> +
>> +    if (ret)
>> +        cpumask_set_cpu(smp_processor_id(), &cpu_evt->error);
>> +}
>> +
>> +static void sse_event_free(struct sse_event *event)
>> +{
>> +    unsigned int cpu;
>> +    struct sse_registered_event *reg_evt;
>> +
>> +    if (sse_event_is_global(event->evt_id)) {
>> +        sse_event_free_registered(event->global);
>> +        kfree(event->global);
>> +    } else {
>> +        for_each_possible_cpu(cpu) {
>> +            reg_evt = per_cpu_ptr(event->local, cpu);
>> +            sse_event_free_registered(reg_evt);
>> +        }
>> +        free_percpu(event->local);
>> +    }
>> +
>> +    kfree(event);
>> +}
>> +
>> +static void sse_on_each_cpu(struct sse_event *event, unsigned long func,
>> +                unsigned long revert_func)
>> +{
>> +    struct sse_per_cpu_evt cpu_evt;
>> +
>> +    cpu_evt.event = event;
>> +    cpumask_clear(&cpu_evt.error);
>> +    cpu_evt.func = func;
>> +    on_each_cpu(sse_event_per_cpu_func, &cpu_evt, 1);
>> +    /*
>> +     * If there are some error reported by CPUs, revert event state
>> on the
>> +     * other ones
>> +     */
>> +    if (!cpumask_empty(&cpu_evt.error)) {
>> +        cpumask_t revert;
>> +
>> +        cpumask_andnot(&revert, cpu_online_mask, &cpu_evt.error);
>> +        cpu_evt.func = revert_func;
>> +        on_each_cpu_mask(&revert, sse_event_per_cpu_func, &cpu_evt, 1);
>> +    }
>> +}
>> +
>> +int sse_event_enable(struct sse_event *event)
>> +{
>> +    int ret = 0;
>> +
>> +    scoped_guard(mutex, &sse_mutex) {
>> +        scoped_guard(cpus_read_lock) {
>> +            if (sse_event_is_global(event->evt_id)) {
>> +                ret = sse_event_enable_local(event);
>> +            } else {
>> +                sse_on_each_cpu(event, SBI_SSE_EVENT_ENABLE,
>> +                        SBI_SSE_EVENT_DISABLE);
>> +            }
>> +        }
>> +    }
>> +    return ret;
>> +}
>> +EXPORT_SYMBOL_GPL(sse_event_enable);
>> +
>> +static int sse_events_mask(void)
>> +{
>> +    struct sbiret ret;
>> +
>> +    ret = sbi_ecall(SBI_EXT_SSE, SBI_SSE_EVENT_HART_MASK, 0, 0, 0, 0,
>> 0, 0);
>> +
>> +    return sbi_err_map_linux_errno(ret.error);
>> +}
>> +
>> +static int sse_events_unmask(void)
>> +{
>> +    struct sbiret ret;
>> +
>> +    ret = sbi_ecall(SBI_EXT_SSE, SBI_SSE_EVENT_HART_UNMASK, 0, 0, 0,
>> 0, 0, 0);
>> +
>> +    return sbi_err_map_linux_errno(ret.error);
>> +}
>> +
>> +static void sse_event_disable_nolock(struct sse_event *event)
>> +{
>> +    struct sse_per_cpu_evt cpu_evt;
>> +
>> +    if (sse_event_is_global(event->evt_id)) {
>> +        sse_event_disable_local(event);
>> +    } else {
>> +        cpu_evt.event = event;
>> +        cpu_evt.func = SBI_SSE_EVENT_DISABLE;
>> +        on_each_cpu(sse_event_per_cpu_func, &cpu_evt, 1);
>> +    }
>> +}
>> +
>> +void sse_event_disable(struct sse_event *event)
>> +{
>> +    scoped_guard(mutex, &sse_mutex) {
>> +        scoped_guard(cpus_read_lock) {
>> +            sse_event_disable_nolock(event);
>> +        }
>> +    }
>> +}
>> +EXPORT_SYMBOL_GPL(sse_event_disable);
>> +
>> +struct sse_event *sse_event_register(u32 evt, u32 priority,
>> +                     sse_event_handler *handler, void *arg)
>> +{
>> +    struct sse_event *event;
>> +    int cpu;
>> +    int ret = 0;
>> +
>> +    if (!sse_available)
>> +        return ERR_PTR(-EOPNOTSUPP);
>> +
>> +    guard(mutex)(&sse_mutex);
>> +    if (sse_event_get(evt))
>> +        return ERR_PTR(-EEXIST);
>> +
>> +    event = sse_event_alloc(evt, priority, handler, arg);
>> +    if (IS_ERR(event))
>> +        return event;
>> +
>> +    scoped_guard(cpus_read_lock) {
>> +        if (sse_event_is_global(evt)) {
>> +            unsigned long preferred_hart;
>> +
>> +            ret = sse_event_attr_get_no_lock(event->global,
>> +                            SBI_SSE_ATTR_PREFERRED_HART,
>> +                            &preferred_hart);
>> +            if (ret)
>> +                goto err_event_free;
>> +
>> +            cpu = riscv_hartid_to_cpuid(preferred_hart);
>> +            sse_global_event_update_cpu(event, cpu);
>> +
>> +            ret = sse_sbi_register_event(event, event->global);
>> +            if (ret)
>> +                goto err_event_free;
>> +
>> +        } else {
>> +            sse_on_each_cpu(event, SBI_SSE_EVENT_REGISTER,
>> +                    SBI_SSE_EVENT_DISABLE);
>> +        }
>> +    }
>> +
>> +    scoped_guard(spinlock, &events_list_lock)
>> +        list_add(&event->list, &events);
>> +
>> +    return event;
>> +
>> +err_event_free:
>> +    sse_event_free(event);
>> +
>> +    return ERR_PTR(ret);
>> +}
>> +EXPORT_SYMBOL_GPL(sse_event_register);
>> +
>> +static void sse_event_unregister_nolock(struct sse_event *event)
>> +{
>> +    struct sse_per_cpu_evt cpu_evt;
>> +
>> +    if (sse_event_is_global(event->evt_id)) {
>> +        sse_sbi_unregister_event(event);
>> +    } else {
>> +        cpu_evt.event = event;
>> +        cpu_evt.func = SBI_SSE_EVENT_UNREGISTER;
>> +        on_each_cpu(sse_event_per_cpu_func, &cpu_evt, 1);
>> +    }
>> +}
>> +
>> +void sse_event_unregister(struct sse_event *event)
>> +{
>> +    scoped_guard(mutex, &sse_mutex) {
>> +        scoped_guard(cpus_read_lock)
>> +            sse_event_unregister_nolock(event);
>> +
>> +        scoped_guard(spinlock, &events_list_lock)
>> +            list_del(&event->list);
>> +
>> +        sse_event_free(event);
>> +    }
>> +}
>> +EXPORT_SYMBOL_GPL(sse_event_unregister);
>> +
>> +static int sse_cpu_online(unsigned int cpu)
>> +{
>> +    struct sse_event *event;
>> +
>> +    scoped_guard(spinlock, &events_list_lock) {
>> +        list_for_each_entry(event, &events, list) {
>> +            if (sse_event_is_global(event->evt_id))
>> +                continue;
>> +
>> +            sse_event_register_local(event);
>> +            if (sse_get_reg_evt(event))
>> +                sse_event_enable_local(event);
>> +        }
>> +    }
>> +
>> +    /* Ready to handle events. Unmask SSE. */
>> +    return sse_events_unmask();
>> +}
>> +
>> +static int sse_cpu_teardown(unsigned int cpu)
>> +{
>> +    int ret = 0;
>> +    unsigned int next_cpu;
>> +    struct sse_event *event;
>> +
>> +    /* Mask the sse events */
>> +    ret = sse_events_mask();
>> +    if (ret)
>> +        return ret;
>> +
>> +    scoped_guard(spinlock, &events_list_lock) {
>> +        list_for_each_entry(event, &events, list) {
>> +            if (!sse_event_is_global(event->evt_id)) {
>> +                if (event->global->is_enabled)
>> +                    sse_event_disable_local(event);
>> +
>> +                sse_sbi_unregister_event(event);
>> +                continue;
>> +            }
>> +
>> +            if (event->cpu != smp_processor_id())
>> +                continue;
>> +
>> +            /* Update destination hart for global event */
>> +            next_cpu = cpumask_any_but(cpu_online_mask, cpu);
>> +            ret = sse_event_set_target_cpu_nolock(event, next_cpu);
>> +        }
>> +    }
>> +
>> +    return ret;
>> +}
>> +
>> +static void sse_reset(void)
>> +{
>> +    struct sse_event *event;
>> +
>> +    list_for_each_entry(event, &events, list) {
>> +        sse_event_disable_nolock(event);
>> +        sse_event_unregister_nolock(event);
>> +    }
>> +}
>> +
>> +static int sse_pm_notifier(struct notifier_block *nb, unsigned long
>> action,
>> +               void *data)
>> +{
>> +    WARN_ON_ONCE(preemptible());
>> +
>> +    switch (action) {
>> +    case CPU_PM_ENTER:
>> +        sse_events_mask();
>> +        break;
>> +    case CPU_PM_EXIT:
>> +    case CPU_PM_ENTER_FAILED:
>> +        sse_events_unmask();
>> +        break;
>> +    default:
>> +        return NOTIFY_DONE;
>> +    }
>> +
>> +    return NOTIFY_OK;
>> +}
>> +
>> +static struct notifier_block sse_pm_nb = {
>> +    .notifier_call = sse_pm_notifier,
>> +};
>> +
>> +/*
>> + * Mask all CPUs and unregister all events on panic, reboot or kexec.
>> + */
>> +static int sse_reboot_notifier(struct notifier_block *nb, unsigned
>> long action,
>> +                   void *data)
>> +{
>> +    cpuhp_remove_state(sse_hp_state);
>> +    sse_reset();
>> +
>> +    return NOTIFY_OK;
>> +}
>> +
>> +static struct notifier_block sse_reboot_nb = {
>> +    .notifier_call = sse_reboot_notifier,
>> +};
>> +
>> +static int __init sse_init(void)
>> +{
>> +    int ret;
>> +
>> +    if (sbi_probe_extension(SBI_EXT_SSE) <= 0) {
>> +        pr_err("Missing SBI SSE extension\n");
>> +        return -EOPNOTSUPP;
>> +    }
>> +    pr_info("SBI SSE extension detected\n");
>> +
>> +    ret = cpu_pm_register_notifier(&sse_pm_nb);
>> +    if (ret) {
>> +        pr_warn("Failed to register CPU PM notifier...\n");
>> +        return ret;
>> +    }
>> +
>> +    ret = register_reboot_notifier(&sse_reboot_nb);
>> +    if (ret) {
>> +        pr_warn("Failed to register reboot notifier...\n");
>> +        goto remove_cpupm;
>> +    }
>> +
>> +    ret = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "riscv/sse:online",
>> +                sse_cpu_online, sse_cpu_teardown);
>> +    if (ret < 0)
>> +        goto remove_reboot;
>> +
>> +    sse_hp_state = ret;
>> +    sse_available = true;
>> +
>> +    return 0;
>> +
>> +remove_reboot:
>> +    unregister_reboot_notifier(&sse_reboot_nb);
>> +
>> +remove_cpupm:
>> +    cpu_pm_unregister_notifier(&sse_pm_nb);
>> +
>> +    return ret;
>> +}
>> +arch_initcall(sse_init);
>> diff --git a/include/linux/riscv_sse.h b/include/linux/riscv_sse.h
>> new file mode 100644
>> index 000000000000..d7bd0e22a00f
>> --- /dev/null
>> +++ b/include/linux/riscv_sse.h
>> @@ -0,0 +1,56 @@
>> +/* SPDX-License-Identifier: GPL-2.0 */
>> +/*
>> + * Copyright (C) 2024 Rivos Inc.
>> + */
>> +
>> +#ifndef __LINUX_RISCV_SSE_H
>> +#define __LINUX_RISCV_SSE_H
>> +
>> +#include <linux/types.h>
>> +#include <linux/linkage.h>
>> +
>> +struct sse_event;
>> +struct pt_regs;
>> +
>> +typedef int (sse_event_handler)(u32 event_num, void *arg, struct
>> pt_regs *regs);
> 
> 
> I don't see function pointer listed here https://www.kernel.org/doc/
> html/v4.10/process/coding-style.html#typedefs so I'd rather avoid this one.

Although not mentionned here, there are function typedefs in the kernel:

git grep (typedef.*_fn)

This one is used at various places of the driver and is quite long so I
would prefer to keep it. I'll rename it sse_event_handler_fn like a
majority of the one in the kernel though.

Thanks,

Clément

> 
> 
>> +
>> +#ifdef CONFIG_RISCV_SSE
>> +
>> +struct sse_event *sse_event_register(u32 event_num, u32 priority,
>> +                     sse_event_handler *handler, void *arg);
>> +
>> +void sse_event_unregister(struct sse_event *evt);
>> +
>> +int sse_event_set_target_cpu(struct sse_event *sse_evt, unsigned int
>> cpu);
>> +
>> +int sse_event_enable(struct sse_event *sse_evt);
>> +
>> +void sse_event_disable(struct sse_event *sse_evt);
>> +
>> +int sse_event_enable_local(struct sse_event *sse_evt);
>> +int sse_event_disable_local(struct sse_event *sse_evt);
>> +
>> +#else
>> +static inline struct sse_event *sse_event_register(u32 event_num, u32
>> priority,
>> +                           sse_event_handler *handler,
>> +                           void *arg)
>> +{
>> +    return ERR_PTR(-EOPNOTSUPP);
>> +}
>> +
>> +static inline void sse_event_unregister(struct sse_event *evt) {}
>> +
>> +static inline int sse_event_set_target_cpu(struct sse_event *sse_evt,
>> +                       unsigned int cpu)
>> +{
>> +    return -EOPNOTSUPP;
>> +}
>> +
>> +static inline int sse_event_enable(struct sse_event *sse_evt)
>> +{
>> +    return -EOPNOTSUPP;
>> +}
>> +
>> +static inline void sse_event_disable(struct sse_event *sse_evt) {}
>> +#endif
>> +#endif /* __LINUX_RISCV_SSE_H */

Re: [External] [PATCH v6 3/5] drivers: firmware: add riscv SSE support

Posted by yunhui cui 6 months ago

Hi Clément,

On Fri, Aug 8, 2025 at 11:39 PM Clément Léger <cleger@rivosinc.com> wrote:
>
> Add driver level interface to use RISC-V SSE arch support. This interface
> allows registering SSE handlers, and receive them. This will be used by
> PMU and GHES driver.
>
> Signed-off-by: Himanshu Chauhan <hchauhan@ventanamicro.com>
> Co-developed-by: Himanshu Chauhan <hchauhan@ventanamicro.com>
> Signed-off-by: Clément Léger <cleger@rivosinc.com>
> Acked-by: Conor Dooley <conor.dooley@microchip.com>
> ---
>  MAINTAINERS                        |  15 +
>  drivers/firmware/Kconfig           |   1 +
>  drivers/firmware/Makefile          |   1 +
>  drivers/firmware/riscv/Kconfig     |  15 +
>  drivers/firmware/riscv/Makefile    |   3 +
>  drivers/firmware/riscv/riscv_sse.c | 694 +++++++++++++++++++++++++++++
>  include/linux/riscv_sse.h          |  56 +++
>  7 files changed, 785 insertions(+)
>  create mode 100644 drivers/firmware/riscv/Kconfig
>  create mode 100644 drivers/firmware/riscv/Makefile
>  create mode 100644 drivers/firmware/riscv/riscv_sse.c
>  create mode 100644 include/linux/riscv_sse.h
>
> diff --git a/MAINTAINERS b/MAINTAINERS
> index bd62ad58a47f..114396d47f76 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -21640,6 +21640,13 @@ T:     git git://git.kernel.org/pub/scm/linux/kernel/git/iommu/linux.git
>  F:     Documentation/devicetree/bindings/iommu/riscv,iommu.yaml
>  F:     drivers/iommu/riscv/
>
> +RISC-V FIRMWARE DRIVERS
> +M:     Conor Dooley <conor@kernel.org>
> +L:     linux-riscv@lists.infradead.org
> +S:     Maintained
> +T:     git git://git.kernel.org/pub/scm/linux/kernel/git/conor/linux.git
> +F:     drivers/firmware/riscv/*
> +
>  RISC-V MICROCHIP FPGA SUPPORT
>  M:     Conor Dooley <conor.dooley@microchip.com>
>  M:     Daire McNamara <daire.mcnamara@microchip.com>
> @@ -21704,6 +21711,14 @@ F:     arch/riscv/boot/dts/spacemit/
>  N:     spacemit
>  K:     spacemit
>
> +RISC-V SSE DRIVER
> +M:     Clément Léger <cleger@rivosinc.com>
> +R:     Himanshu Chauhan <himanshu@thechauhan.dev>
> +L:     linux-riscv@lists.infradead.org
> +S:     Maintained
> +F:     drivers/firmware/riscv/riscv_sse.c
> +F:     include/linux/riscv_sse.h
> +
>  RISC-V THEAD SoC SUPPORT
>  M:     Drew Fustini <fustini@kernel.org>
>  M:     Guo Ren <guoren@kernel.org>
> diff --git a/drivers/firmware/Kconfig b/drivers/firmware/Kconfig
> index bbd2155d8483..1894df87b08e 100644
> --- a/drivers/firmware/Kconfig
> +++ b/drivers/firmware/Kconfig
> @@ -294,6 +294,7 @@ source "drivers/firmware/meson/Kconfig"
>  source "drivers/firmware/microchip/Kconfig"
>  source "drivers/firmware/psci/Kconfig"
>  source "drivers/firmware/qcom/Kconfig"
> +source "drivers/firmware/riscv/Kconfig"
>  source "drivers/firmware/samsung/Kconfig"
>  source "drivers/firmware/smccc/Kconfig"
>  source "drivers/firmware/tegra/Kconfig"
> diff --git a/drivers/firmware/Makefile b/drivers/firmware/Makefile
> index 4ddec2820c96..6cdd84570ea7 100644
> --- a/drivers/firmware/Makefile
> +++ b/drivers/firmware/Makefile
> @@ -34,6 +34,7 @@ obj-y                         += efi/
>  obj-y                          += imx/
>  obj-y                          += psci/
>  obj-y                          += qcom/
> +obj-y                          += riscv/
>  obj-y                          += samsung/
>  obj-y                          += smccc/
>  obj-y                          += tegra/
> diff --git a/drivers/firmware/riscv/Kconfig b/drivers/firmware/riscv/Kconfig
> new file mode 100644
> index 000000000000..8056ed3262d9
> --- /dev/null
> +++ b/drivers/firmware/riscv/Kconfig
> @@ -0,0 +1,15 @@
> +# SPDX-License-Identifier: GPL-2.0-only
> +menu "Risc-V Specific firmware drivers"
> +depends on RISCV
> +
> +config RISCV_SSE
> +       bool "Enable SBI Supervisor Software Events support"
> +       depends on RISCV_SBI
> +       default y
> +       help
> +         The Supervisor Software Events support allow the SBI to deliver
> +         NMI-like notifications to the supervisor mode software. When enable,
> +         this option provides support to register callbacks on specific SSE
> +         events.
> +
> +endmenu
> diff --git a/drivers/firmware/riscv/Makefile b/drivers/firmware/riscv/Makefile
> new file mode 100644
> index 000000000000..4ccfcbbc28ea
> --- /dev/null
> +++ b/drivers/firmware/riscv/Makefile
> @@ -0,0 +1,3 @@
> +# SPDX-License-Identifier: GPL-2.0
> +
> +obj-$(CONFIG_RISCV_SSE)                += riscv_sse.o
> diff --git a/drivers/firmware/riscv/riscv_sse.c b/drivers/firmware/riscv/riscv_sse.c
> new file mode 100644
> index 000000000000..edd107ade94a
> --- /dev/null
> +++ b/drivers/firmware/riscv/riscv_sse.c
> @@ -0,0 +1,694 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +/*
> + * Copyright (C) 2024 Rivos Inc.
> + */
> +
> +#define pr_fmt(fmt) "sse: " fmt
> +
> +#include <linux/cpu.h>
> +#include <linux/cpuhotplug.h>
> +#include <linux/cpu_pm.h>
> +#include <linux/hardirq.h>
> +#include <linux/list.h>
> +#include <linux/percpu-defs.h>
> +#include <linux/reboot.h>
> +#include <linux/riscv_sse.h>
> +#include <linux/slab.h>
> +
> +#include <asm/sbi.h>
> +#include <asm/sse.h>
> +
> +struct sse_event {
> +       struct list_head list;
> +       u32 evt_id;
> +       u32 priority;
> +       sse_event_handler *handler;
> +       void *handler_arg;
> +       /* Only valid for global events */
> +       unsigned int cpu;
> +
> +       union {
> +               struct sse_registered_event *global;
> +               struct sse_registered_event __percpu *local;
> +       };
> +};
> +
> +static int sse_hp_state;
> +static bool sse_available __ro_after_init;
> +static DEFINE_SPINLOCK(events_list_lock);
> +static LIST_HEAD(events);
> +static DEFINE_MUTEX(sse_mutex);
> +
> +struct sse_registered_event {
> +       struct sse_event_arch_data arch;
> +       struct sse_event *event;
> +       unsigned long attr;
> +       bool is_enabled;
> +};
> +
> +void sse_handle_event(struct sse_event_arch_data *arch_event,
> +                     struct pt_regs *regs)
> +{
> +       int ret;
> +       struct sse_registered_event *reg_evt =
> +               container_of(arch_event, struct sse_registered_event, arch);
> +       struct sse_event *evt = reg_evt->event;
> +
> +       ret = evt->handler(evt->evt_id, evt->handler_arg, regs);
> +       if (ret)
> +               pr_warn("event %x handler failed with error %d\n", evt->evt_id, ret);
> +}
> +
> +static struct sse_event *sse_event_get(u32 evt)
> +{
> +       struct sse_event *event = NULL;
> +
> +       scoped_guard(spinlock, &events_list_lock) {
> +               list_for_each_entry(event, &events, list) {
> +                       if (event->evt_id == evt)
> +                               return event;
> +               }
> +       }
> +
> +       return NULL;
> +}
> +
> +static phys_addr_t sse_event_get_attr_phys(struct sse_registered_event *reg_evt)
> +{
> +       phys_addr_t phys;
> +       void *addr = &reg_evt->attr;
> +
> +       if (sse_event_is_global(reg_evt->event->evt_id))
> +               phys = virt_to_phys(addr);
> +       else
> +               phys = per_cpu_ptr_to_phys(addr);
> +
> +       return phys;
> +}
> +
> +static struct sse_registered_event *sse_get_reg_evt(struct sse_event *event)
> +{
> +       if (sse_event_is_global(event->evt_id))
> +               return event->global;
> +       else
> +               return per_cpu_ptr(event->local, smp_processor_id());
> +}
> +
> +static int sse_sbi_event_func(struct sse_event *event, unsigned long func)
> +{
> +       struct sbiret ret;
> +       u32 evt = event->evt_id;
> +       struct sse_registered_event *reg_evt = sse_get_reg_evt(event);
> +
> +       ret = sbi_ecall(SBI_EXT_SSE, func, evt, 0, 0, 0, 0, 0);
> +       if (ret.error) {
> +               pr_warn("Failed to execute func %lx, event %x, error %ld\n",
> +                       func, evt, ret.error);
> +               return sbi_err_map_linux_errno(ret.error);
> +       }
> +
> +       if (func == SBI_SSE_EVENT_DISABLE)
> +               reg_evt->is_enabled = false;
> +       else if (func == SBI_SSE_EVENT_ENABLE)
> +               reg_evt->is_enabled = true;
> +
> +       return 0;
> +}
> +
> +int sse_event_disable_local(struct sse_event *event)
> +{
> +       return sse_sbi_event_func(event, SBI_SSE_EVENT_DISABLE);
> +}
> +EXPORT_SYMBOL_GPL(sse_event_disable_local);
> +
> +int sse_event_enable_local(struct sse_event *event)
> +{
> +       return sse_sbi_event_func(event, SBI_SSE_EVENT_ENABLE);
> +}
> +EXPORT_SYMBOL_GPL(sse_event_enable_local);
> +
> +static int sse_event_attr_get_no_lock(struct sse_registered_event *reg_evt,
> +                                     unsigned long attr_id, unsigned long *val)
> +{
> +       struct sbiret sret;
> +       u32 evt = reg_evt->event->evt_id;
> +       unsigned long phys;
> +
> +       phys = sse_event_get_attr_phys(reg_evt);
> +
> +       sret = sbi_ecall(SBI_EXT_SSE, SBI_SSE_EVENT_ATTR_READ, evt, attr_id, 1,
> +                        phys, 0, 0);
> +       if (sret.error) {
> +               pr_debug("Failed to get event %x attr %lx, error %ld\n", evt,
> +                        attr_id, sret.error);
> +               return sbi_err_map_linux_errno(sret.error);
> +       }
> +
> +       *val = reg_evt->attr;
> +
> +       return 0;
> +}
> +
> +static int sse_event_attr_set_nolock(struct sse_registered_event *reg_evt,
> +                                    unsigned long attr_id, unsigned long val)
> +{
> +       struct sbiret sret;
> +       u32 evt = reg_evt->event->evt_id;
> +       unsigned long phys;
> +
> +       reg_evt->attr = val;
> +       phys = sse_event_get_attr_phys(reg_evt);
> +
> +       sret = sbi_ecall(SBI_EXT_SSE, SBI_SSE_EVENT_ATTR_WRITE, evt, attr_id, 1,
> +                        phys, 0, 0);
> +       if (sret.error)
> +               pr_debug("Failed to set event %x attr %lx, error %ld\n", evt,
> +                        attr_id, sret.error);
> +
> +       return sbi_err_map_linux_errno(sret.error);
> +}
> +
> +static void sse_global_event_update_cpu(struct sse_event *event,
> +                                       unsigned int cpu)
> +{
> +       struct sse_registered_event *reg_evt = event->global;
> +
> +       event->cpu = cpu;
> +       arch_sse_event_update_cpu(&reg_evt->arch, cpu);
> +}
> +
> +static int sse_event_set_target_cpu_nolock(struct sse_event *event,
> +                                          unsigned int cpu)
> +{
> +       unsigned int hart_id = cpuid_to_hartid_map(cpu);
> +       struct sse_registered_event *reg_evt = event->global;
> +       u32 evt = event->evt_id;
> +       bool was_enabled;
> +       int ret;
> +
> +       if (!sse_event_is_global(evt))
> +               return -EINVAL;
> +
> +       was_enabled = reg_evt->is_enabled;
> +       if (was_enabled)
> +               sse_event_disable_local(event);
> +
> +       ret = sse_event_attr_set_nolock(reg_evt, SBI_SSE_ATTR_PREFERRED_HART,
> +                                       hart_id);
> +       if (ret == 0)
> +               sse_global_event_update_cpu(event, cpu);
> +
> +       if (was_enabled)
> +               sse_event_enable_local(event);
> +
> +       return 0;
> +}
> +
> +int sse_event_set_target_cpu(struct sse_event *event, unsigned int cpu)
> +{
> +       int ret;
> +
> +       scoped_guard(mutex, &sse_mutex) {
> +               scoped_guard(cpus_read_lock) {
> +                       if (!cpu_online(cpu))
> +                               return -EINVAL;
> +
> +                       ret = sse_event_set_target_cpu_nolock(event, cpu);
> +               }
> +       }
> +
> +       return ret;
> +}
> +EXPORT_SYMBOL_GPL(sse_event_set_target_cpu);
> +
> +static int sse_event_init_registered(unsigned int cpu,
> +                                    struct sse_registered_event *reg_evt,
> +                                    struct sse_event *event)
> +{
> +       reg_evt->event = event;
> +
> +       return arch_sse_init_event(&reg_evt->arch, event->evt_id, cpu);
> +}
> +
> +static void sse_event_free_registered(struct sse_registered_event *reg_evt)
> +{
> +       arch_sse_free_event(&reg_evt->arch);
> +}
> +
> +static int sse_event_alloc_global(struct sse_event *event)
> +{
> +       int err;
> +       struct sse_registered_event *reg_evt;
> +
> +       reg_evt = kzalloc(sizeof(*reg_evt), GFP_KERNEL);
> +       if (!reg_evt)
> +               return -ENOMEM;
> +
> +       event->global = reg_evt;
> +       err = sse_event_init_registered(smp_processor_id(), reg_evt, event);
> +       if (err)
> +               kfree(reg_evt);
> +
> +       return err;
> +}
> +
> +static int sse_event_alloc_local(struct sse_event *event)
> +{
> +       int err;
> +       unsigned int cpu, err_cpu;
> +       struct sse_registered_event *reg_evt;
> +       struct sse_registered_event __percpu *reg_evts;
> +
> +       reg_evts = alloc_percpu(struct sse_registered_event);
> +       if (!reg_evts)
> +               return -ENOMEM;
> +
> +       event->local = reg_evts;
> +
> +       for_each_possible_cpu(cpu) {
> +               reg_evt = per_cpu_ptr(reg_evts, cpu);
> +               err = sse_event_init_registered(cpu, reg_evt, event);
> +               if (err) {
> +                       err_cpu = cpu;
> +                       goto err_free_per_cpu;
> +               }
> +       }
> +
> +       return 0;
> +
> +err_free_per_cpu:
> +       for_each_possible_cpu(cpu) {
> +               if (cpu == err_cpu)
> +                       break;
> +               reg_evt = per_cpu_ptr(reg_evts, cpu);
> +               sse_event_free_registered(reg_evt);
> +       }
> +
> +       free_percpu(reg_evts);
> +
> +       return err;
> +}
> +
> +static struct sse_event *sse_event_alloc(u32 evt, u32 priority,
> +                                        sse_event_handler *handler, void *arg)
> +{
> +       int err;
> +       struct sse_event *event;
> +
> +       event = kzalloc(sizeof(*event), GFP_KERNEL);
> +       if (!event)
> +               return ERR_PTR(-ENOMEM);
> +
> +       event->evt_id = evt;
> +       event->priority = priority;
> +       event->handler_arg = arg;
> +       event->handler = handler;
> +
> +       if (sse_event_is_global(evt))
> +               err = sse_event_alloc_global(event);
> +       else
> +               err = sse_event_alloc_local(event);
> +
> +       if (err) {
> +               kfree(event);
> +               return ERR_PTR(err);
> +       }
> +
> +       return event;
> +}
> +
> +static int sse_sbi_register_event(struct sse_event *event,
> +                                 struct sse_registered_event *reg_evt)
> +{
> +       int ret;
> +
> +       ret = sse_event_attr_set_nolock(reg_evt, SBI_SSE_ATTR_PRIO,
> +                                       event->priority);
> +       if (ret)
> +               return ret;
> +
> +       return arch_sse_register_event(&reg_evt->arch);
> +}
> +
> +static int sse_event_register_local(struct sse_event *event)
> +{
> +       int ret;
> +       struct sse_registered_event *reg_evt;
> +
> +       reg_evt = per_cpu_ptr(event->local, smp_processor_id());
> +       ret = sse_sbi_register_event(event, reg_evt);
> +       if (ret)
> +               pr_debug("Failed to register event %x: err %d\n", event->evt_id,
> +                        ret);
> +
> +       return ret;
> +}
> +
> +static int sse_sbi_unregister_event(struct sse_event *event)
> +{
> +       return sse_sbi_event_func(event, SBI_SSE_EVENT_UNREGISTER);
> +}
> +
> +struct sse_per_cpu_evt {
> +       struct sse_event *event;
> +       unsigned long func;
> +       cpumask_t error;
> +};
> +
> +static void sse_event_per_cpu_func(void *info)
> +{
> +       int ret;
> +       struct sse_per_cpu_evt *cpu_evt = info;
> +
> +       if (cpu_evt->func == SBI_SSE_EVENT_REGISTER)
> +               ret = sse_event_register_local(cpu_evt->event);
> +       else
> +               ret = sse_sbi_event_func(cpu_evt->event, cpu_evt->func);
> +
> +       if (ret)
> +               cpumask_set_cpu(smp_processor_id(), &cpu_evt->error);
> +}
> +
> +static void sse_event_free(struct sse_event *event)
> +{
> +       unsigned int cpu;
> +       struct sse_registered_event *reg_evt;
> +
> +       if (sse_event_is_global(event->evt_id)) {
> +               sse_event_free_registered(event->global);
> +               kfree(event->global);
> +       } else {
> +               for_each_possible_cpu(cpu) {
> +                       reg_evt = per_cpu_ptr(event->local, cpu);
> +                       sse_event_free_registered(reg_evt);
> +               }
> +               free_percpu(event->local);
> +       }
> +
> +       kfree(event);
> +}
> +
> +static void sse_on_each_cpu(struct sse_event *event, unsigned long func,
> +                           unsigned long revert_func)
> +{
> +       struct sse_per_cpu_evt cpu_evt;
> +
> +       cpu_evt.event = event;
> +       cpumask_clear(&cpu_evt.error);
> +       cpu_evt.func = func;
> +       on_each_cpu(sse_event_per_cpu_func, &cpu_evt, 1);
> +       /*
> +        * If there are some error reported by CPUs, revert event state on the
> +        * other ones
> +        */
> +       if (!cpumask_empty(&cpu_evt.error)) {
> +               cpumask_t revert;
> +
> +               cpumask_andnot(&revert, cpu_online_mask, &cpu_evt.error);
> +               cpu_evt.func = revert_func;
> +               on_each_cpu_mask(&revert, sse_event_per_cpu_func, &cpu_evt, 1);
> +       }
> +}
> +
> +int sse_event_enable(struct sse_event *event)
> +{
> +       int ret = 0;
> +
> +       scoped_guard(mutex, &sse_mutex) {
> +               scoped_guard(cpus_read_lock) {
> +                       if (sse_event_is_global(event->evt_id)) {
> +                               ret = sse_event_enable_local(event);
> +                       } else {
> +                               sse_on_each_cpu(event, SBI_SSE_EVENT_ENABLE,
> +                                               SBI_SSE_EVENT_DISABLE);
> +                       }
> +               }
> +       }
> +       return ret;
> +}
> +EXPORT_SYMBOL_GPL(sse_event_enable);
> +
> +static int sse_events_mask(void)
> +{
> +       struct sbiret ret;
> +
> +       ret = sbi_ecall(SBI_EXT_SSE, SBI_SSE_EVENT_HART_MASK, 0, 0, 0, 0, 0, 0);
> +
> +       return sbi_err_map_linux_errno(ret.error);
> +}
> +
> +static int sse_events_unmask(void)
> +{
> +       struct sbiret ret;
> +
> +       ret = sbi_ecall(SBI_EXT_SSE, SBI_SSE_EVENT_HART_UNMASK, 0, 0, 0, 0, 0, 0);
> +
> +       return sbi_err_map_linux_errno(ret.error);
> +}
> +
> +static void sse_event_disable_nolock(struct sse_event *event)
> +{
> +       struct sse_per_cpu_evt cpu_evt;
> +
> +       if (sse_event_is_global(event->evt_id)) {
> +               sse_event_disable_local(event);
> +       } else {
> +               cpu_evt.event = event;
> +               cpu_evt.func = SBI_SSE_EVENT_DISABLE;
> +               on_each_cpu(sse_event_per_cpu_func, &cpu_evt, 1);
> +       }
> +}
> +
> +void sse_event_disable(struct sse_event *event)
> +{
> +       scoped_guard(mutex, &sse_mutex) {
> +               scoped_guard(cpus_read_lock) {
> +                       sse_event_disable_nolock(event);
> +               }
> +       }
> +}
> +EXPORT_SYMBOL_GPL(sse_event_disable);
> +
> +struct sse_event *sse_event_register(u32 evt, u32 priority,
> +                                    sse_event_handler *handler, void *arg)
> +{
> +       struct sse_event *event;
> +       int cpu;
> +       int ret = 0;
> +
> +       if (!sse_available)
> +               return ERR_PTR(-EOPNOTSUPP);
> +
> +       guard(mutex)(&sse_mutex);
> +       if (sse_event_get(evt))
> +               return ERR_PTR(-EEXIST);
> +
> +       event = sse_event_alloc(evt, priority, handler, arg);
> +       if (IS_ERR(event))
> +               return event;
> +
> +       scoped_guard(cpus_read_lock) {
> +               if (sse_event_is_global(evt)) {
> +                       unsigned long preferred_hart;
> +
> +                       ret = sse_event_attr_get_no_lock(event->global,
> +                                                       SBI_SSE_ATTR_PREFERRED_HART,
> +                                                       &preferred_hart);
> +                       if (ret)
> +                               goto err_event_free;
> +
> +                       cpu = riscv_hartid_to_cpuid(preferred_hart);
> +                       sse_global_event_update_cpu(event, cpu);
> +
> +                       ret = sse_sbi_register_event(event, event->global);
> +                       if (ret)
> +                               goto err_event_free;
> +
> +               } else {
> +                       sse_on_each_cpu(event, SBI_SSE_EVENT_REGISTER,
> +                                       SBI_SSE_EVENT_DISABLE);
> +               }

It is necessary to check the return value; otherwise, the event might
be passed as a valid value to subsequent logic, such as
sse_event_enable().


> +       }
> +
> +       scoped_guard(spinlock, &events_list_lock)
> +               list_add(&event->list, &events);
> +
> +       return event;
> +
> +err_event_free:
> +       sse_event_free(event);
> +
> +       return ERR_PTR(ret);
> +}
> +EXPORT_SYMBOL_GPL(sse_event_register);
> +
> +static void sse_event_unregister_nolock(struct sse_event *event)
> +{
> +       struct sse_per_cpu_evt cpu_evt;
> +
> +       if (sse_event_is_global(event->evt_id)) {
> +               sse_sbi_unregister_event(event);
> +       } else {
> +               cpu_evt.event = event;
> +               cpu_evt.func = SBI_SSE_EVENT_UNREGISTER;
> +               on_each_cpu(sse_event_per_cpu_func, &cpu_evt, 1);
> +       }
> +}
> +
> +void sse_event_unregister(struct sse_event *event)
> +{
> +       scoped_guard(mutex, &sse_mutex) {
> +               scoped_guard(cpus_read_lock)
> +                       sse_event_unregister_nolock(event);
> +
> +               scoped_guard(spinlock, &events_list_lock)
> +                       list_del(&event->list);
> +
> +               sse_event_free(event);
> +       }
> +}
> +EXPORT_SYMBOL_GPL(sse_event_unregister);
> +
> +static int sse_cpu_online(unsigned int cpu)
> +{
> +       struct sse_event *event;
> +
> +       scoped_guard(spinlock, &events_list_lock) {
> +               list_for_each_entry(event, &events, list) {
> +                       if (sse_event_is_global(event->evt_id))
> +                               continue;
> +
> +                       sse_event_register_local(event);
> +                       if (sse_get_reg_evt(event))
> +                               sse_event_enable_local(event);
> +               }
> +       }
> +
> +       /* Ready to handle events. Unmask SSE. */
> +       return sse_events_unmask();
> +}
> +
> +static int sse_cpu_teardown(unsigned int cpu)
> +{
> +       int ret = 0;
> +       unsigned int next_cpu;
> +       struct sse_event *event;
> +
> +       /* Mask the sse events */
> +       ret = sse_events_mask();
> +       if (ret)
> +               return ret;
> +
> +       scoped_guard(spinlock, &events_list_lock) {
> +               list_for_each_entry(event, &events, list) {
> +                       if (!sse_event_is_global(event->evt_id)) {
> +                               if (event->global->is_enabled)
> +                                       sse_event_disable_local(event);
> +
> +                               sse_sbi_unregister_event(event);
> +                               continue;
> +                       }
> +
> +                       if (event->cpu != smp_processor_id())
> +                               continue;
> +
> +                       /* Update destination hart for global event */
> +                       next_cpu = cpumask_any_but(cpu_online_mask, cpu);
> +                       ret = sse_event_set_target_cpu_nolock(event, next_cpu);
> +               }
> +       }
> +
> +       return ret;
> +}
> +
> +static void sse_reset(void)
> +{
> +       struct sse_event *event;
> +
> +       list_for_each_entry(event, &events, list) {
> +               sse_event_disable_nolock(event);
> +               sse_event_unregister_nolock(event);
> +       }
> +}
> +
> +static int sse_pm_notifier(struct notifier_block *nb, unsigned long action,
> +                          void *data)
> +{
> +       WARN_ON_ONCE(preemptible());
> +
> +       switch (action) {
> +       case CPU_PM_ENTER:
> +               sse_events_mask();
> +               break;
> +       case CPU_PM_EXIT:
> +       case CPU_PM_ENTER_FAILED:
> +               sse_events_unmask();
> +               break;
> +       default:
> +               return NOTIFY_DONE;
> +       }
> +
> +       return NOTIFY_OK;
> +}
> +
> +static struct notifier_block sse_pm_nb = {
> +       .notifier_call = sse_pm_notifier,
> +};
> +
> +/*
> + * Mask all CPUs and unregister all events on panic, reboot or kexec.
> + */
> +static int sse_reboot_notifier(struct notifier_block *nb, unsigned long action,
> +                              void *data)
> +{
> +       cpuhp_remove_state(sse_hp_state);
> +       sse_reset();
> +
> +       return NOTIFY_OK;
> +}
> +
> +static struct notifier_block sse_reboot_nb = {
> +       .notifier_call = sse_reboot_notifier,
> +};
> +
> +static int __init sse_init(void)
> +{
> +       int ret;
> +
> +       if (sbi_probe_extension(SBI_EXT_SSE) <= 0) {
> +               pr_err("Missing SBI SSE extension\n");
> +               return -EOPNOTSUPP;
> +       }
> +       pr_info("SBI SSE extension detected\n");
> +
> +       ret = cpu_pm_register_notifier(&sse_pm_nb);
> +       if (ret) {
> +               pr_warn("Failed to register CPU PM notifier...\n");
> +               return ret;
> +       }
> +
> +       ret = register_reboot_notifier(&sse_reboot_nb);
> +       if (ret) {
> +               pr_warn("Failed to register reboot notifier...\n");
> +               goto remove_cpupm;
> +       }
> +
> +       ret = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "riscv/sse:online",
> +                               sse_cpu_online, sse_cpu_teardown);
> +       if (ret < 0)
> +               goto remove_reboot;
> +
> +       sse_hp_state = ret;
> +       sse_available = true;
> +
> +       return 0;
> +
> +remove_reboot:
> +       unregister_reboot_notifier(&sse_reboot_nb);
> +
> +remove_cpupm:
> +       cpu_pm_unregister_notifier(&sse_pm_nb);
> +
> +       return ret;
> +}
> +arch_initcall(sse_init);
> diff --git a/include/linux/riscv_sse.h b/include/linux/riscv_sse.h
> new file mode 100644
> index 000000000000..d7bd0e22a00f
> --- /dev/null
> +++ b/include/linux/riscv_sse.h
> @@ -0,0 +1,56 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +/*
> + * Copyright (C) 2024 Rivos Inc.
> + */
> +
> +#ifndef __LINUX_RISCV_SSE_H
> +#define __LINUX_RISCV_SSE_H
> +
> +#include <linux/types.h>
> +#include <linux/linkage.h>
> +
> +struct sse_event;
> +struct pt_regs;
> +
> +typedef int (sse_event_handler)(u32 event_num, void *arg, struct pt_regs *regs);
> +
> +#ifdef CONFIG_RISCV_SSE
> +
> +struct sse_event *sse_event_register(u32 event_num, u32 priority,
> +                                    sse_event_handler *handler, void *arg);
> +
> +void sse_event_unregister(struct sse_event *evt);
> +
> +int sse_event_set_target_cpu(struct sse_event *sse_evt, unsigned int cpu);
> +
> +int sse_event_enable(struct sse_event *sse_evt);
> +
> +void sse_event_disable(struct sse_event *sse_evt);
> +
> +int sse_event_enable_local(struct sse_event *sse_evt);
> +int sse_event_disable_local(struct sse_event *sse_evt);
> +
> +#else
> +static inline struct sse_event *sse_event_register(u32 event_num, u32 priority,
> +                                                  sse_event_handler *handler,
> +                                                  void *arg)
> +{
> +       return ERR_PTR(-EOPNOTSUPP);
> +}
> +
> +static inline void sse_event_unregister(struct sse_event *evt) {}
> +
> +static inline int sse_event_set_target_cpu(struct sse_event *sse_evt,
> +                                          unsigned int cpu)
> +{
> +       return -EOPNOTSUPP;
> +}
> +
> +static inline int sse_event_enable(struct sse_event *sse_evt)
> +{
> +       return -EOPNOTSUPP;
> +}
> +
> +static inline void sse_event_disable(struct sse_event *sse_evt) {}
> +#endif
> +#endif /* __LINUX_RISCV_SSE_H */
> --
> 2.43.0
>

Thanks,
Yunhui

Re: [External] [PATCH v6 3/5] drivers: firmware: add riscv SSE support

Posted by Clément Léger 6 months ago


On 12/08/2025 14:54, yunhui cui wrote:
>>                                                       &preferred_hart);
>> +                       if (ret)
>> +                               goto err_event_free;
>> +
>> +                       cpu = riscv_hartid_to_cpuid(preferred_hart);
>> +                       sse_global_event_update_cpu(event, cpu);
>> +
>> +                       ret = sse_sbi_register_event(event, event->global);
>> +                       if (ret)
>> +                               goto err_event_free;
>> +
>> +               } else {
>> +                       sse_on_each_cpu(event, SBI_SSE_EVENT_REGISTER,
>> +                                       SBI_SSE_EVENT_DISABLE);
>> +               }
> It is necessary to check the return value; otherwise, the event might
> be passed as a valid value to subsequent logic, such as
> sse_event_enable().
> 
> 

Hi Yunhui,

Indeed, nice catch. I'll fix that.

Thanks,

Clément

[PATCH v6 1/5] riscv: add SBI SSE extension definitions
[PATCH v6 2/5] riscv: add support for SBI Supervisor Software Events extension
[PATCH v6 3/5] drivers: firmware: add riscv SSE support
[PATCH v6 4/5] perf: RISC-V: add support for SSE event
[PATCH v6 5/5] selftests/riscv: add SSE test module