Allow the creation of hypervisor and trace remote events with a single
macro HYP_EVENT(). That macro expands in the kernel side to add all
the required declarations (based on REMOTE_EVENT()) as well as in the
hypervisor side to create the trace_<event>() function.
Signed-off-by: Vincent Donnefort <vdonnefort@google.com>
diff --git a/arch/arm64/include/asm/kvm_asm.h b/arch/arm64/include/asm/kvm_asm.h
index 4faabf398881..f7b29eae7010 100644
--- a/arch/arm64/include/asm/kvm_asm.h
+++ b/arch/arm64/include/asm/kvm_asm.h
@@ -95,6 +95,7 @@ enum __kvm_host_smccc_func {
__KVM_HOST_SMCCC_FUNC___pkvm_enable_tracing,
__KVM_HOST_SMCCC_FUNC___pkvm_reset_tracing,
__KVM_HOST_SMCCC_FUNC___pkvm_swap_reader_tracing,
+ __KVM_HOST_SMCCC_FUNC___pkvm_enable_event,
};
#define DECLARE_KVM_VHE_SYM(sym) extern char sym[]
diff --git a/arch/arm64/include/asm/kvm_define_hypevents.h b/arch/arm64/include/asm/kvm_define_hypevents.h
new file mode 100644
index 000000000000..0ef5a9eefcbe
--- /dev/null
+++ b/arch/arm64/include/asm/kvm_define_hypevents.h
@@ -0,0 +1,21 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+
+#ifndef HYP_EVENT_FILE
+# undef __ARM64_KVM_HYPEVENTS_H_
+# define REMOTE_EVENT_INCLUDE_FILE arch/arm64/include/asm/kvm_hypevents.h
+#else
+# define REMOTE_EVENT_INCLUDE_FILE HYP_EVENT_FILE
+#endif
+
+#define REMOTE_EVENT_SECTION "_hyp_events"
+
+#define HE_STRUCT(__args) __args
+#define HE_PRINTK(__args...) __args
+#define he_field re_field
+
+#define HYP_EVENT(__name, __proto, __struct, __assign, __printk) \
+ REMOTE_EVENT(__name, 0, RE_STRUCT(__struct), RE_PRINTK(__printk))
+
+#define HYP_EVENT_MULTI_READ
+
+#include <trace/define_remote_events.h>
diff --git a/arch/arm64/include/asm/kvm_hypevents.h b/arch/arm64/include/asm/kvm_hypevents.h
new file mode 100644
index 000000000000..d6e033c96c52
--- /dev/null
+++ b/arch/arm64/include/asm/kvm_hypevents.h
@@ -0,0 +1,10 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+
+#if !defined(__ARM64_KVM_HYPEVENTS_H_) || defined(HYP_EVENT_MULTI_READ)
+#define __ARM64_KVM_HYPEVENTS_H_
+
+#ifdef __KVM_NVHE_HYPERVISOR__
+#include <nvhe/trace.h>
+#endif
+
+#endif
diff --git a/arch/arm64/include/asm/kvm_hyptrace.h b/arch/arm64/include/asm/kvm_hyptrace.h
index 9c30a479bc36..d6e0953a07d6 100644
--- a/arch/arm64/include/asm/kvm_hyptrace.h
+++ b/arch/arm64/include/asm/kvm_hyptrace.h
@@ -10,4 +10,17 @@ struct hyp_trace_desc {
struct trace_buffer_desc trace_buffer_desc;
};
+
+struct hyp_event_id {
+ unsigned short id;
+ void *data;
+};
+
+extern struct remote_event __hyp_events_start[];
+extern struct remote_event __hyp_events_end[];
+
+/* hyp_event section used by the hypervisor */
+extern struct hyp_event_id __hyp_event_ids_start[];
+extern struct hyp_event_id __hyp_event_ids_end[];
+
#endif
diff --git a/arch/arm64/kernel/image-vars.h b/arch/arm64/kernel/image-vars.h
index 5369763606e7..c0efa9aa541b 100644
--- a/arch/arm64/kernel/image-vars.h
+++ b/arch/arm64/kernel/image-vars.h
@@ -137,6 +137,10 @@ KVM_NVHE_ALIAS(__hyp_data_start);
KVM_NVHE_ALIAS(__hyp_data_end);
KVM_NVHE_ALIAS(__hyp_rodata_start);
KVM_NVHE_ALIAS(__hyp_rodata_end);
+#ifdef CONFIG_PKVM_TRACING
+KVM_NVHE_ALIAS(__hyp_event_ids_start);
+KVM_NVHE_ALIAS(__hyp_event_ids_end);
+#endif
/* pKVM static key */
KVM_NVHE_ALIAS(kvm_protected_mode_initialized);
diff --git a/arch/arm64/kernel/vmlinux.lds.S b/arch/arm64/kernel/vmlinux.lds.S
index ad6133b89e7a..0e201a3c8de5 100644
--- a/arch/arm64/kernel/vmlinux.lds.S
+++ b/arch/arm64/kernel/vmlinux.lds.S
@@ -13,12 +13,23 @@
*(__kvm_ex_table) \
__stop___kvm_ex_table = .;
+#ifdef CONFIG_PKVM_TRACING
+#define HYPERVISOR_EVENT_IDS \
+ . = ALIGN(PAGE_SIZE); \
+ __hyp_event_ids_start = .; \
+ *(HYP_SECTION_NAME(.event_ids)) \
+ __hyp_event_ids_end = .;
+#else
+#define HYPERVISOR_EVENT_IDS
+#endif
+
#define HYPERVISOR_RODATA_SECTIONS \
HYP_SECTION_NAME(.rodata) : { \
. = ALIGN(PAGE_SIZE); \
__hyp_rodata_start = .; \
*(HYP_SECTION_NAME(.data..ro_after_init)) \
*(HYP_SECTION_NAME(.rodata)) \
+ HYPERVISOR_EVENT_IDS \
. = ALIGN(PAGE_SIZE); \
__hyp_rodata_end = .; \
}
@@ -307,6 +318,13 @@ SECTIONS
HYPERVISOR_DATA_SECTION
+#ifdef CONFIG_PKVM_TRACING
+ .data.hyp_events : {
+ __hyp_events_start = .;
+ *(SORT(_hyp_events.*))
+ __hyp_events_end = .;
+ }
+#endif
/*
* Data written with the MMU off but read with the MMU on requires
* cache lines to be invalidated, discarding up to a Cache Writeback
diff --git a/arch/arm64/kvm/hyp/include/nvhe/define_events.h b/arch/arm64/kvm/hyp/include/nvhe/define_events.h
new file mode 100644
index 000000000000..2298b49cb355
--- /dev/null
+++ b/arch/arm64/kvm/hyp/include/nvhe/define_events.h
@@ -0,0 +1,21 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+
+#ifndef HYP_EVENT_FILE
+# define __HYP_EVENT_FILE <asm/kvm_hypevents.h>
+#else
+# define __HYP_EVENT_FILE __stringify(HYP_EVENT_FILE)
+#endif
+
+#undef HYP_EVENT
+#define HYP_EVENT(__name, __proto, __struct, __assign, __printk) \
+ atomic_t __ro_after_init __name##_enabled = ATOMIC_INIT(0); \
+ struct hyp_event_id hyp_event_id_##__name \
+ __section(".hyp.event_ids."#__name) = { \
+ .data = (void *)&__name##_enabled, \
+ }
+
+#define HYP_EVENT_MULTI_READ
+#include __HYP_EVENT_FILE
+#undef HYP_EVENT_MULTI_READ
+
+#undef HYP_EVENT
diff --git a/arch/arm64/kvm/hyp/include/nvhe/trace.h b/arch/arm64/kvm/hyp/include/nvhe/trace.h
index 0d2732f0d406..f7b286e92853 100644
--- a/arch/arm64/kvm/hyp/include/nvhe/trace.h
+++ b/arch/arm64/kvm/hyp/include/nvhe/trace.h
@@ -1,21 +1,52 @@
/* SPDX-License-Identifier: GPL-2.0-only */
#ifndef __ARM64_KVM_HYP_NVHE_TRACE_H
#define __ARM64_KVM_HYP_NVHE_TRACE_H
+
+#include <linux/trace_remote_event.h>
+
#include <asm/kvm_hyptrace.h>
+#define HE_PROTO(__args...) __args
+
#ifdef CONFIG_PKVM_TRACING
void *tracing_reserve_entry(unsigned long length);
void tracing_commit_entry(void);
+#define HE_ASSIGN(__args...) __args
+#define HE_STRUCT RE_STRUCT
+#define he_field re_field
+
+#define HYP_EVENT(__name, __proto, __struct, __assign, __printk) \
+ REMOTE_EVENT_FORMAT(__name, __struct); \
+ extern atomic_t __name##_enabled; \
+ extern struct hyp_event_id hyp_event_id_##__name; \
+ static __always_inline void trace_##__name(__proto) \
+ { \
+ struct remote_event_format_##__name *__entry; \
+ size_t length = sizeof(*__entry); \
+ \
+ if (!atomic_read(&__name##_enabled)) \
+ return; \
+ __entry = tracing_reserve_entry(length); \
+ if (!__entry) \
+ return; \
+ __entry->hdr.id = hyp_event_id_##__name.id; \
+ __assign \
+ tracing_commit_entry(); \
+ }
+
void __pkvm_update_clock_tracing(u32 mult, u32 shift, u64 epoch_ns, u64 epoch_cyc);
int __pkvm_load_tracing(unsigned long desc_va, size_t desc_size);
void __pkvm_unload_tracing(void);
int __pkvm_enable_tracing(bool enable);
int __pkvm_reset_tracing(unsigned int cpu);
int __pkvm_swap_reader_tracing(unsigned int cpu);
+int __pkvm_enable_event(unsigned short id, bool enable);
#else
static inline void *tracing_reserve_entry(unsigned long length) { return NULL; }
static inline void tracing_commit_entry(void) { }
+#define HYP_EVENT(__name, __proto, __struct, __assign, __printk) \
+ static inline void trace_##__name(__proto) {}
static inline
void __pkvm_update_clock_tracing(u32 mult, u32 shift, u64 epoch_ns, u64 epoch_cyc) { }
@@ -24,5 +55,6 @@ static inline void __pkvm_unload_tracing(void) { }
static inline int __pkvm_enable_tracing(bool enable) { return -ENODEV; }
static inline int __pkvm_reset_tracing(unsigned int cpu) { return -ENODEV; }
static inline int __pkvm_swap_reader_tracing(unsigned int cpu) { return -ENODEV; }
+static inline int __pkvm_enable_event(unsigned short id, bool enable) { return -ENODEV; }
#endif
#endif
diff --git a/arch/arm64/kvm/hyp/nvhe/Makefile b/arch/arm64/kvm/hyp/nvhe/Makefile
index 504c3b9caef8..b77959e963f3 100644
--- a/arch/arm64/kvm/hyp/nvhe/Makefile
+++ b/arch/arm64/kvm/hyp/nvhe/Makefile
@@ -29,7 +29,7 @@ hyp-obj-y += ../vgic-v3-sr.o ../aarch32.o ../vgic-v2-cpuif-proxy.o ../entry.o \
../fpsimd.o ../hyp-entry.o ../exception.o ../pgtable.o
hyp-obj-y += ../../../kernel/smccc-call.o
hyp-obj-$(CONFIG_LIST_HARDENED) += list_debug.o
-hyp-obj-$(CONFIG_PKVM_TRACING) += clock.o trace.o ../../../../../kernel/trace/simple_ring_buffer.o
+hyp-obj-$(CONFIG_PKVM_TRACING) += clock.o trace.o ../../../../../kernel/trace/simple_ring_buffer.o events.o
hyp-obj-y += $(lib-objs)
##
diff --git a/arch/arm64/kvm/hyp/nvhe/events.c b/arch/arm64/kvm/hyp/nvhe/events.c
new file mode 100644
index 000000000000..5905b42cb0d0
--- /dev/null
+++ b/arch/arm64/kvm/hyp/nvhe/events.c
@@ -0,0 +1,36 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (C) 2025 Google LLC
+ * Author: Vincent Donnefort <vdonnefort@google.com>
+ */
+
+#include <nvhe/mm.h>
+#include <nvhe/trace.h>
+
+#include <nvhe/define_events.h>
+
+extern struct hyp_event_id __hyp_event_ids_start[];
+extern struct hyp_event_id __hyp_event_ids_end[];
+
+int __pkvm_enable_event(unsigned short id, bool enable)
+{
+ struct hyp_event_id *event_id = __hyp_event_ids_start;
+ atomic_t *enable_key;
+
+ for (; (unsigned long)event_id < (unsigned long)__hyp_event_ids_end;
+ event_id++) {
+ if (event_id->id != id)
+ continue;
+
+ enable_key = (atomic_t *)event_id->data;
+ enable_key = hyp_fixmap_map(__hyp_pa(enable_key));
+
+ atomic_set(enable_key, enable);
+
+ hyp_fixmap_unmap();
+
+ return 0;
+ }
+
+ return -EINVAL;
+}
diff --git a/arch/arm64/kvm/hyp/nvhe/hyp-main.c b/arch/arm64/kvm/hyp/nvhe/hyp-main.c
index 8adad701fc76..5e4b519e5204 100644
--- a/arch/arm64/kvm/hyp/nvhe/hyp-main.c
+++ b/arch/arm64/kvm/hyp/nvhe/hyp-main.c
@@ -634,6 +634,14 @@ static void handle___pkvm_swap_reader_tracing(struct kvm_cpu_context *host_ctxt)
cpu_reg(host_ctxt, 1) = __pkvm_swap_reader_tracing(cpu);
}
+static void handle___pkvm_enable_event(struct kvm_cpu_context *host_ctxt)
+{
+ DECLARE_REG(unsigned short, id, host_ctxt, 1);
+ DECLARE_REG(bool, enable, host_ctxt, 2);
+
+ cpu_reg(host_ctxt, 1) = __pkvm_enable_event(id, enable);
+}
+
typedef void (*hcall_t)(struct kvm_cpu_context *);
#define HANDLE_FUNC(x) [__KVM_HOST_SMCCC_FUNC_##x] = (hcall_t)handle_##x
@@ -681,6 +689,7 @@ static const hcall_t host_hcall[] = {
HANDLE_FUNC(__pkvm_enable_tracing),
HANDLE_FUNC(__pkvm_reset_tracing),
HANDLE_FUNC(__pkvm_swap_reader_tracing),
+ HANDLE_FUNC(__pkvm_enable_event),
};
static void handle_host_hcall(struct kvm_cpu_context *host_ctxt)
diff --git a/arch/arm64/kvm/hyp/nvhe/hyp.lds.S b/arch/arm64/kvm/hyp/nvhe/hyp.lds.S
index d724f6d69302..a68411bf4bef 100644
--- a/arch/arm64/kvm/hyp/nvhe/hyp.lds.S
+++ b/arch/arm64/kvm/hyp/nvhe/hyp.lds.S
@@ -16,6 +16,12 @@ SECTIONS {
HYP_SECTION(.text)
HYP_SECTION(.data..ro_after_init)
HYP_SECTION(.rodata)
+#ifdef CONFIG_PKVM_TRACING
+ . = ALIGN(PAGE_SIZE);
+ BEGIN_HYP_SECTION(.event_ids)
+ *(SORT(.hyp.event_ids.*))
+ END_HYP_SECTION
+#endif
/*
* .hyp..data..percpu needs to be page aligned to maintain the same
diff --git a/arch/arm64/kvm/hyp_trace.c b/arch/arm64/kvm/hyp_trace.c
index 1062b4310f8c..73539f5b5e42 100644
--- a/arch/arm64/kvm/hyp_trace.c
+++ b/arch/arm64/kvm/hyp_trace.c
@@ -307,7 +307,7 @@ static int hyp_trace_reset(unsigned int cpu, void *priv)
static int hyp_trace_enable_event(unsigned short id, bool enable, void *priv)
{
- return 0;
+ return kvm_call_hyp_nvhe(__pkvm_enable_event, id, enable);
}
static int hyp_trace_clock_show(struct seq_file *m, void *v)
@@ -334,10 +334,27 @@ static struct trace_remote_callbacks trace_remote_callbacks = {
.enable_event = hyp_trace_enable_event,
};
+#include <asm/kvm_define_hypevents.h>
+
+static void hyp_trace_init_events(void)
+{
+ struct hyp_event_id *hyp_event_id = __hyp_event_ids_start;
+ struct remote_event *event = __hyp_events_start;
+ int id = 0;
+
+ /* Events on both sides hypervisor are sorted */
+ for (; (unsigned long)event < (unsigned long)__hyp_events_end;
+ event++, hyp_event_id++, id++)
+ event->id = hyp_event_id->id = id;
+}
+
int hyp_trace_init(void)
{
if (!is_protected_kvm_enabled())
return 0;
- return trace_remote_register("hypervisor", &trace_remote_callbacks, &trace_buffer, NULL, 0);
+ hyp_trace_init_events();
+
+ return trace_remote_register("hypervisor", &trace_remote_callbacks, &trace_buffer,
+ __hyp_events_start, __hyp_events_end - __hyp_events_start);
}
diff --git a/kernel/trace/trace_remote.c b/kernel/trace/trace_remote.c
index 4f2b67d1bfec..e54cc3e75dc5 100644
--- a/kernel/trace/trace_remote.c
+++ b/kernel/trace/trace_remote.c
@@ -1040,7 +1040,7 @@ static int remote_event_format_show(struct seq_file *s, void *unused)
while (field->name) {
seq_printf(s, "\tfield:%s %s;\toffset:%zu;\tsize:%u;\tsigned:%d;\n",
field->type, field->name, offset, field->size,
- !field->is_signed);
+ field->is_signed);
offset += field->size;
field++;
}
@@ -1071,7 +1071,7 @@ static int remote_event_callback(const char *name, umode_t *mode, void **data,
if (!strcmp(name, "format")) {
*mode = TRACEFS_MODE_READ;
- *fops = &remote_event_id_fops;
+ *fops = &remote_event_format_fops;
return 1;
}
--
2.51.2.1041.gc1ab5b90ca-googOn Fri, 07 Nov 2025 09:38:37 +0000,
Vincent Donnefort <vdonnefort@google.com> wrote:
>
> Allow the creation of hypervisor and trace remote events with a single
> macro HYP_EVENT(). That macro expands in the kernel side to add all
> the required declarations (based on REMOTE_EVENT()) as well as in the
> hypervisor side to create the trace_<event>() function.
>
> Signed-off-by: Vincent Donnefort <vdonnefort@google.com>
>
> diff --git a/arch/arm64/include/asm/kvm_asm.h b/arch/arm64/include/asm/kvm_asm.h
> index 4faabf398881..f7b29eae7010 100644
> --- a/arch/arm64/include/asm/kvm_asm.h
> +++ b/arch/arm64/include/asm/kvm_asm.h
> @@ -95,6 +95,7 @@ enum __kvm_host_smccc_func {
> __KVM_HOST_SMCCC_FUNC___pkvm_enable_tracing,
> __KVM_HOST_SMCCC_FUNC___pkvm_reset_tracing,
> __KVM_HOST_SMCCC_FUNC___pkvm_swap_reader_tracing,
> + __KVM_HOST_SMCCC_FUNC___pkvm_enable_event,
nit: add 'tracing' to the name of the function, like its little
friends. Saves us from wondering whether this is about PMU events or
not...
> };
>
> #define DECLARE_KVM_VHE_SYM(sym) extern char sym[]
> diff --git a/arch/arm64/include/asm/kvm_define_hypevents.h b/arch/arm64/include/asm/kvm_define_hypevents.h
> new file mode 100644
> index 000000000000..0ef5a9eefcbe
> --- /dev/null
> +++ b/arch/arm64/include/asm/kvm_define_hypevents.h
> @@ -0,0 +1,21 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +
> +#ifndef HYP_EVENT_FILE
> +# undef __ARM64_KVM_HYPEVENTS_H_
> +# define REMOTE_EVENT_INCLUDE_FILE arch/arm64/include/asm/kvm_hypevents.h
> +#else
> +# define REMOTE_EVENT_INCLUDE_FILE HYP_EVENT_FILE
> +#endif
I'm feeling a bit sick here. Can you please document here how the
whole repainting trickery works, how the event equivalence works, and
what the whole thing depends on? I *really* don't want to have to
reverse engineer this stuff when it will break.
> +
> +#define REMOTE_EVENT_SECTION "_hyp_events"
> +
> +#define HE_STRUCT(__args) __args
> +#define HE_PRINTK(__args...) __args
> +#define he_field re_field
> +
> +#define HYP_EVENT(__name, __proto, __struct, __assign, __printk) \
> + REMOTE_EVENT(__name, 0, RE_STRUCT(__struct), RE_PRINTK(__printk))
> +
> +#define HYP_EVENT_MULTI_READ
> +
> +#include <trace/define_remote_events.h>
> diff --git a/arch/arm64/include/asm/kvm_hypevents.h b/arch/arm64/include/asm/kvm_hypevents.h
> new file mode 100644
> index 000000000000..d6e033c96c52
> --- /dev/null
> +++ b/arch/arm64/include/asm/kvm_hypevents.h
> @@ -0,0 +1,10 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +
> +#if !defined(__ARM64_KVM_HYPEVENTS_H_) || defined(HYP_EVENT_MULTI_READ)
> +#define __ARM64_KVM_HYPEVENTS_H_
> +
> +#ifdef __KVM_NVHE_HYPERVISOR__
> +#include <nvhe/trace.h>
> +#endif
> +
> +#endif
> diff --git a/arch/arm64/include/asm/kvm_hyptrace.h b/arch/arm64/include/asm/kvm_hyptrace.h
> index 9c30a479bc36..d6e0953a07d6 100644
> --- a/arch/arm64/include/asm/kvm_hyptrace.h
> +++ b/arch/arm64/include/asm/kvm_hyptrace.h
> @@ -10,4 +10,17 @@ struct hyp_trace_desc {
> struct trace_buffer_desc trace_buffer_desc;
>
> };
> +
> +struct hyp_event_id {
> + unsigned short id;
> + void *data;
> +};
> +
> +extern struct remote_event __hyp_events_start[];
> +extern struct remote_event __hyp_events_end[];
> +
> +/* hyp_event section used by the hypervisor */
> +extern struct hyp_event_id __hyp_event_ids_start[];
> +extern struct hyp_event_id __hyp_event_ids_end[];
> +
> #endif
> diff --git a/arch/arm64/kernel/image-vars.h b/arch/arm64/kernel/image-vars.h
> index 5369763606e7..c0efa9aa541b 100644
> --- a/arch/arm64/kernel/image-vars.h
> +++ b/arch/arm64/kernel/image-vars.h
> @@ -137,6 +137,10 @@ KVM_NVHE_ALIAS(__hyp_data_start);
> KVM_NVHE_ALIAS(__hyp_data_end);
> KVM_NVHE_ALIAS(__hyp_rodata_start);
> KVM_NVHE_ALIAS(__hyp_rodata_end);
> +#ifdef CONFIG_PKVM_TRACING
> +KVM_NVHE_ALIAS(__hyp_event_ids_start);
> +KVM_NVHE_ALIAS(__hyp_event_ids_end);
> +#endif
>
> /* pKVM static key */
> KVM_NVHE_ALIAS(kvm_protected_mode_initialized);
> diff --git a/arch/arm64/kernel/vmlinux.lds.S b/arch/arm64/kernel/vmlinux.lds.S
> index ad6133b89e7a..0e201a3c8de5 100644
> --- a/arch/arm64/kernel/vmlinux.lds.S
> +++ b/arch/arm64/kernel/vmlinux.lds.S
> @@ -13,12 +13,23 @@
> *(__kvm_ex_table) \
> __stop___kvm_ex_table = .;
>
> +#ifdef CONFIG_PKVM_TRACING
> +#define HYPERVISOR_EVENT_IDS \
> + . = ALIGN(PAGE_SIZE); \
> + __hyp_event_ids_start = .; \
> + *(HYP_SECTION_NAME(.event_ids)) \
> + __hyp_event_ids_end = .;
> +#else
> +#define HYPERVISOR_EVENT_IDS
> +#endif
> +
> #define HYPERVISOR_RODATA_SECTIONS \
> HYP_SECTION_NAME(.rodata) : { \
> . = ALIGN(PAGE_SIZE); \
> __hyp_rodata_start = .; \
> *(HYP_SECTION_NAME(.data..ro_after_init)) \
> *(HYP_SECTION_NAME(.rodata)) \
> + HYPERVISOR_EVENT_IDS \
> . = ALIGN(PAGE_SIZE); \
> __hyp_rodata_end = .; \
> }
> @@ -307,6 +318,13 @@ SECTIONS
>
> HYPERVISOR_DATA_SECTION
>
> +#ifdef CONFIG_PKVM_TRACING
> + .data.hyp_events : {
> + __hyp_events_start = .;
> + *(SORT(_hyp_events.*))
> + __hyp_events_end = .;
> + }
> +#endif
> /*
> * Data written with the MMU off but read with the MMU on requires
> * cache lines to be invalidated, discarding up to a Cache Writeback
> diff --git a/arch/arm64/kvm/hyp/include/nvhe/define_events.h b/arch/arm64/kvm/hyp/include/nvhe/define_events.h
> new file mode 100644
> index 000000000000..2298b49cb355
> --- /dev/null
> +++ b/arch/arm64/kvm/hyp/include/nvhe/define_events.h
> @@ -0,0 +1,21 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +
> +#ifndef HYP_EVENT_FILE
> +# define __HYP_EVENT_FILE <asm/kvm_hypevents.h>
> +#else
> +# define __HYP_EVENT_FILE __stringify(HYP_EVENT_FILE)
> +#endif
> +
> +#undef HYP_EVENT
> +#define HYP_EVENT(__name, __proto, __struct, __assign, __printk) \
> + atomic_t __ro_after_init __name##_enabled = ATOMIC_INIT(0); \
> + struct hyp_event_id hyp_event_id_##__name \
> + __section(".hyp.event_ids."#__name) = { \
> + .data = (void *)&__name##_enabled, \
> + }
> +
> +#define HYP_EVENT_MULTI_READ
> +#include __HYP_EVENT_FILE
> +#undef HYP_EVENT_MULTI_READ
> +
> +#undef HYP_EVENT
> diff --git a/arch/arm64/kvm/hyp/include/nvhe/trace.h b/arch/arm64/kvm/hyp/include/nvhe/trace.h
> index 0d2732f0d406..f7b286e92853 100644
> --- a/arch/arm64/kvm/hyp/include/nvhe/trace.h
> +++ b/arch/arm64/kvm/hyp/include/nvhe/trace.h
> @@ -1,21 +1,52 @@
> /* SPDX-License-Identifier: GPL-2.0-only */
> #ifndef __ARM64_KVM_HYP_NVHE_TRACE_H
> #define __ARM64_KVM_HYP_NVHE_TRACE_H
> +
> +#include <linux/trace_remote_event.h>
> +
> #include <asm/kvm_hyptrace.h>
>
> +#define HE_PROTO(__args...) __args
> +
> #ifdef CONFIG_PKVM_TRACING
> void *tracing_reserve_entry(unsigned long length);
> void tracing_commit_entry(void);
>
> +#define HE_ASSIGN(__args...) __args
> +#define HE_STRUCT RE_STRUCT
> +#define he_field re_field
> +
> +#define HYP_EVENT(__name, __proto, __struct, __assign, __printk) \
> + REMOTE_EVENT_FORMAT(__name, __struct); \
> + extern atomic_t __name##_enabled; \
> + extern struct hyp_event_id hyp_event_id_##__name; \
> + static __always_inline void trace_##__name(__proto) \
> + { \
> + struct remote_event_format_##__name *__entry; \
> + size_t length = sizeof(*__entry); \
> + \
> + if (!atomic_read(&__name##_enabled)) \
> + return; \
> + __entry = tracing_reserve_entry(length); \
> + if (!__entry) \
> + return; \
> + __entry->hdr.id = hyp_event_id_##__name.id; \
> + __assign \
> + tracing_commit_entry(); \
> + }
> +
> void __pkvm_update_clock_tracing(u32 mult, u32 shift, u64 epoch_ns, u64 epoch_cyc);
> int __pkvm_load_tracing(unsigned long desc_va, size_t desc_size);
> void __pkvm_unload_tracing(void);
> int __pkvm_enable_tracing(bool enable);
> int __pkvm_reset_tracing(unsigned int cpu);
> int __pkvm_swap_reader_tracing(unsigned int cpu);
> +int __pkvm_enable_event(unsigned short id, bool enable);
> #else
> static inline void *tracing_reserve_entry(unsigned long length) { return NULL; }
> static inline void tracing_commit_entry(void) { }
> +#define HYP_EVENT(__name, __proto, __struct, __assign, __printk) \
> + static inline void trace_##__name(__proto) {}
>
> static inline
> void __pkvm_update_clock_tracing(u32 mult, u32 shift, u64 epoch_ns, u64 epoch_cyc) { }
> @@ -24,5 +55,6 @@ static inline void __pkvm_unload_tracing(void) { }
> static inline int __pkvm_enable_tracing(bool enable) { return -ENODEV; }
> static inline int __pkvm_reset_tracing(unsigned int cpu) { return -ENODEV; }
> static inline int __pkvm_swap_reader_tracing(unsigned int cpu) { return -ENODEV; }
> +static inline int __pkvm_enable_event(unsigned short id, bool enable) { return -ENODEV; }
> #endif
> #endif
> diff --git a/arch/arm64/kvm/hyp/nvhe/Makefile b/arch/arm64/kvm/hyp/nvhe/Makefile
> index 504c3b9caef8..b77959e963f3 100644
> --- a/arch/arm64/kvm/hyp/nvhe/Makefile
> +++ b/arch/arm64/kvm/hyp/nvhe/Makefile
> @@ -29,7 +29,7 @@ hyp-obj-y += ../vgic-v3-sr.o ../aarch32.o ../vgic-v2-cpuif-proxy.o ../entry.o \
> ../fpsimd.o ../hyp-entry.o ../exception.o ../pgtable.o
> hyp-obj-y += ../../../kernel/smccc-call.o
> hyp-obj-$(CONFIG_LIST_HARDENED) += list_debug.o
> -hyp-obj-$(CONFIG_PKVM_TRACING) += clock.o trace.o ../../../../../kernel/trace/simple_ring_buffer.o
> +hyp-obj-$(CONFIG_PKVM_TRACING) += clock.o trace.o ../../../../../kernel/trace/simple_ring_buffer.o events.o
> hyp-obj-y += $(lib-objs)
>
> ##
> diff --git a/arch/arm64/kvm/hyp/nvhe/events.c b/arch/arm64/kvm/hyp/nvhe/events.c
> new file mode 100644
> index 000000000000..5905b42cb0d0
> --- /dev/null
> +++ b/arch/arm64/kvm/hyp/nvhe/events.c
> @@ -0,0 +1,36 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +/*
> + * Copyright (C) 2025 Google LLC
> + * Author: Vincent Donnefort <vdonnefort@google.com>
> + */
> +
> +#include <nvhe/mm.h>
> +#include <nvhe/trace.h>
> +
> +#include <nvhe/define_events.h>
> +
> +extern struct hyp_event_id __hyp_event_ids_start[];
> +extern struct hyp_event_id __hyp_event_ids_end[];
Isn't that already declared in an include file?
> +
> +int __pkvm_enable_event(unsigned short id, bool enable)
> +{
> + struct hyp_event_id *event_id = __hyp_event_ids_start;
> + atomic_t *enable_key;
> +
> + for (; (unsigned long)event_id < (unsigned long)__hyp_event_ids_end;
> + event_id++) {
> + if (event_id->id != id)
> + continue;
> +
> + enable_key = (atomic_t *)event_id->data;
> + enable_key = hyp_fixmap_map(__hyp_pa(enable_key));
> +
> + atomic_set(enable_key, enable);
> +
> + hyp_fixmap_unmap();
> +
> + return 0;
> + }
> +
> + return -EINVAL;
> +}
> diff --git a/arch/arm64/kvm/hyp/nvhe/hyp-main.c b/arch/arm64/kvm/hyp/nvhe/hyp-main.c
> index 8adad701fc76..5e4b519e5204 100644
> --- a/arch/arm64/kvm/hyp/nvhe/hyp-main.c
> +++ b/arch/arm64/kvm/hyp/nvhe/hyp-main.c
> @@ -634,6 +634,14 @@ static void handle___pkvm_swap_reader_tracing(struct kvm_cpu_context *host_ctxt)
> cpu_reg(host_ctxt, 1) = __pkvm_swap_reader_tracing(cpu);
> }
>
> +static void handle___pkvm_enable_event(struct kvm_cpu_context *host_ctxt)
> +{
> + DECLARE_REG(unsigned short, id, host_ctxt, 1);
> + DECLARE_REG(bool, enable, host_ctxt, 2);
> +
> + cpu_reg(host_ctxt, 1) = __pkvm_enable_event(id, enable);
> +}
> +
> typedef void (*hcall_t)(struct kvm_cpu_context *);
>
> #define HANDLE_FUNC(x) [__KVM_HOST_SMCCC_FUNC_##x] = (hcall_t)handle_##x
> @@ -681,6 +689,7 @@ static const hcall_t host_hcall[] = {
> HANDLE_FUNC(__pkvm_enable_tracing),
> HANDLE_FUNC(__pkvm_reset_tracing),
> HANDLE_FUNC(__pkvm_swap_reader_tracing),
> + HANDLE_FUNC(__pkvm_enable_event),
> };
>
> static void handle_host_hcall(struct kvm_cpu_context *host_ctxt)
> diff --git a/arch/arm64/kvm/hyp/nvhe/hyp.lds.S b/arch/arm64/kvm/hyp/nvhe/hyp.lds.S
> index d724f6d69302..a68411bf4bef 100644
> --- a/arch/arm64/kvm/hyp/nvhe/hyp.lds.S
> +++ b/arch/arm64/kvm/hyp/nvhe/hyp.lds.S
> @@ -16,6 +16,12 @@ SECTIONS {
> HYP_SECTION(.text)
> HYP_SECTION(.data..ro_after_init)
> HYP_SECTION(.rodata)
> +#ifdef CONFIG_PKVM_TRACING
> + . = ALIGN(PAGE_SIZE);
> + BEGIN_HYP_SECTION(.event_ids)
> + *(SORT(.hyp.event_ids.*))
> + END_HYP_SECTION
> +#endif
>
> /*
> * .hyp..data..percpu needs to be page aligned to maintain the same
> diff --git a/arch/arm64/kvm/hyp_trace.c b/arch/arm64/kvm/hyp_trace.c
> index 1062b4310f8c..73539f5b5e42 100644
> --- a/arch/arm64/kvm/hyp_trace.c
> +++ b/arch/arm64/kvm/hyp_trace.c
> @@ -307,7 +307,7 @@ static int hyp_trace_reset(unsigned int cpu, void *priv)
>
> static int hyp_trace_enable_event(unsigned short id, bool enable, void *priv)
> {
> - return 0;
> + return kvm_call_hyp_nvhe(__pkvm_enable_event, id, enable);
> }
>
> static int hyp_trace_clock_show(struct seq_file *m, void *v)
> @@ -334,10 +334,27 @@ static struct trace_remote_callbacks trace_remote_callbacks = {
> .enable_event = hyp_trace_enable_event,
> };
>
> +#include <asm/kvm_define_hypevents.h>
> +
> +static void hyp_trace_init_events(void)
> +{
> + struct hyp_event_id *hyp_event_id = __hyp_event_ids_start;
> + struct remote_event *event = __hyp_events_start;
> + int id = 0;
> +
> + /* Events on both sides hypervisor are sorted */
> + for (; (unsigned long)event < (unsigned long)__hyp_events_end;
It feels very bizarre that you have to cast anything here. Aren't the
two variables of the same type, part of the same array, and shouldn't
pointer arithmetic apply?
> + event++, hyp_event_id++, id++)
> + event->id = hyp_event_id->id = id;
> +}
> +
> int hyp_trace_init(void)
> {
> if (!is_protected_kvm_enabled())
> return 0;
>
> - return trace_remote_register("hypervisor", &trace_remote_callbacks, &trace_buffer, NULL, 0);
> + hyp_trace_init_events();
> +
> + return trace_remote_register("hypervisor", &trace_remote_callbacks, &trace_buffer,
> + __hyp_events_start, __hyp_events_end - __hyp_events_start);
> }
> diff --git a/kernel/trace/trace_remote.c b/kernel/trace/trace_remote.c
> index 4f2b67d1bfec..e54cc3e75dc5 100644
> --- a/kernel/trace/trace_remote.c
> +++ b/kernel/trace/trace_remote.c
> @@ -1040,7 +1040,7 @@ static int remote_event_format_show(struct seq_file *s, void *unused)
> while (field->name) {
> seq_printf(s, "\tfield:%s %s;\toffset:%zu;\tsize:%u;\tsigned:%d;\n",
> field->type, field->name, offset, field->size,
> - !field->is_signed);
> + field->is_signed);
> offset += field->size;
> field++;
> }
> @@ -1071,7 +1071,7 @@ static int remote_event_callback(const char *name, umode_t *mode, void **data,
>
> if (!strcmp(name, "format")) {
> *mode = TRACEFS_MODE_READ;
> - *fops = &remote_event_id_fops;
> + *fops = &remote_event_format_fops;
> return 1;
> }
>
Thanks,
M.
--
Jazz isn't dead. It just smells funny.
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