Virtual CPU hot-(un)plug events MUST be notified to the GIC. Introduce a
notfication mechanism to update any such events to GIC so that it can update its
vCPU to GIC CPU interface association.
This is required to implement a workaround to the limitations posed by the ARM
architecture. For details about the constraints and workarounds please check
below slides:
Link: https://kvm-forum.qemu.org/2023/talk/9SMPDQ/
Co-developed-by: Keqian Zhu <zhukeqian1@huawei.com>
Signed-off-by: Keqian Zhu <zhukeqian1@huawei.com>
Signed-off-by: Salil Mehta <salil.mehta@huawei.com>
---
hw/arm/virt.c | 27 +++++++++++++--
hw/intc/arm_gicv3_common.c | 54 +++++++++++++++++++++++++++++-
hw/intc/arm_gicv3_cpuif_common.c | 5 +++
hw/intc/gicv3_internal.h | 1 +
include/hw/arm/virt.h | 1 +
include/hw/intc/arm_gicv3_common.h | 22 ++++++++++++
6 files changed, 107 insertions(+), 3 deletions(-)
diff --git a/hw/arm/virt.c b/hw/arm/virt.c
index 1556c362f7..9f7e07bd8e 100644
--- a/hw/arm/virt.c
+++ b/hw/arm/virt.c
@@ -685,6 +685,16 @@ static inline DeviceState *create_acpi_ged(VirtMachineState *vms)
return dev;
}
+static void virt_add_gic_cpuhp_notifier(VirtMachineState *vms)
+{
+ MachineClass *mc = MACHINE_GET_CLASS(vms);
+
+ if (mc->has_hotpluggable_cpus) {
+ Notifier *cpuhp_notifier = gicv3_cpuhp_notifier(vms->gic);
+ notifier_list_add(&vms->cpuhp_notifiers, cpuhp_notifier);
+ }
+}
+
static void create_its(VirtMachineState *vms)
{
const char *itsclass = its_class_name();
@@ -960,6 +970,9 @@ static void create_gic(VirtMachineState *vms, MemoryRegion *mem)
} else if (vms->gic_version == VIRT_GIC_VERSION_2) {
create_v2m(vms);
}
+
+ /* add GIC CPU hot(un)plug update notifier */
+ virt_add_gic_cpuhp_notifier(vms);
}
static void create_uart(const VirtMachineState *vms, int uart,
@@ -2472,6 +2485,8 @@ static void machvirt_init(MachineState *machine)
create_fdt(vms);
+ notifier_list_init(&vms->cpuhp_notifiers);
+
assert(possible_cpus->len == max_cpus);
for (n = 0; n < possible_cpus->len; n++) {
CPUArchId *cpu_slot;
@@ -3054,6 +3069,14 @@ static void virt_memory_plug(HotplugHandler *hotplug_dev,
dev, &error_abort);
}
+static void virt_update_gic(VirtMachineState *vms, CPUState *cs)
+{
+ GICv3CPUHotplugInfo gic_info = { .gic = vms->gic, .cpu = cs };
+
+ /* notify gic to stitch GICC to this new cpu */
+ notifier_list_notify(&vms->cpuhp_notifiers, &gic_info);
+}
+
static void virt_cpu_pre_plug(HotplugHandler *hotplug_dev, DeviceState *dev,
Error **errp)
{
@@ -3128,7 +3151,7 @@ static void virt_cpu_pre_plug(HotplugHandler *hotplug_dev, DeviceState *dev,
* vCPUs have their GIC state initialized during machvit_init().
*/
if (vms->acpi_dev) {
- /* TODO: update GIC about this hotplug change here */
+ virt_update_gic(vms, cs);
wire_gic_cpu_irqs(vms, cs);
}
@@ -3214,7 +3237,7 @@ static void virt_cpu_unplug(HotplugHandler *hotplug_dev, DeviceState *dev,
/* TODO: update the acpi cpu hotplug state for cpu hot-unplug */
unwire_gic_cpu_irqs(vms, cs);
- /* TODO: update the GIC about this hot unplug change */
+ virt_update_gic(vms, cs);
/* TODO: unregister cpu for reset & update F/W info for the next boot */
diff --git a/hw/intc/arm_gicv3_common.c b/hw/intc/arm_gicv3_common.c
index 183d2de7eb..155342055b 100644
--- a/hw/intc/arm_gicv3_common.c
+++ b/hw/intc/arm_gicv3_common.c
@@ -33,7 +33,6 @@
#include "hw/arm/linux-boot-if.h"
#include "sysemu/kvm.h"
-
static void gicv3_gicd_no_migration_shift_bug_post_load(GICv3State *cs)
{
if (cs->gicd_no_migration_shift_bug) {
@@ -366,6 +365,56 @@ void gicv3_init_irqs_and_mmio(GICv3State *s, qemu_irq_handler handler,
}
}
+static int arm_gicv3_get_proc_num(GICv3State *s, CPUState *cpu)
+{
+ uint64_t mp_affinity;
+ uint64_t gicr_typer;
+ uint64_t cpu_affid;
+ int i;
+
+ mp_affinity = object_property_get_uint(OBJECT(cpu), "mp-affinity", NULL);
+ /* match the cpu mp-affinity to get the gic cpuif number */
+ for (i = 0; i < s->num_cpu; i++) {
+ gicr_typer = s->cpu[i].gicr_typer;
+ cpu_affid = (gicr_typer >> 32) & 0xFFFFFF;
+ if (cpu_affid == mp_affinity) {
+ return i;
+ }
+ }
+
+ return -1;
+}
+
+static void arm_gicv3_cpu_update_notifier(Notifier *notifier, void * data)
+{
+ GICv3CPUHotplugInfo *gic_info = (GICv3CPUHotplugInfo *)data;
+ CPUState *cpu = gic_info->cpu;
+ int gic_cpuif_num;
+ GICv3State *s;
+
+ s = ARM_GICV3_COMMON(gic_info->gic);
+
+ /* this shall get us mapped gicv3 cpuif corresponding to mpidr */
+ gic_cpuif_num = arm_gicv3_get_proc_num(s, cpu);
+ if (gic_cpuif_num < 0) {
+ error_report("Failed to associate cpu %d with any GIC cpuif",
+ cpu->cpu_index);
+ abort();
+ }
+
+ /* check if update is for vcpu hot-unplug */
+ if (qemu_enabled_cpu(cpu)) {
+ s->cpu[gic_cpuif_num].cpu = NULL;
+ return;
+ }
+
+ /* re-stitch the gic cpuif to this new cpu */
+ gicv3_set_gicv3state(cpu, &s->cpu[gic_cpuif_num]);
+ gicv3_set_cpustate(&s->cpu[gic_cpuif_num], cpu);
+
+ /* TODO: initialize the registers info for this newly added cpu */
+}
+
static void arm_gicv3_common_realize(DeviceState *dev, Error **errp)
{
GICv3State *s = ARM_GICV3_COMMON(dev);
@@ -488,6 +537,8 @@ static void arm_gicv3_common_realize(DeviceState *dev, Error **errp)
s->cpu[cpuidx - 1].gicr_typer |= GICR_TYPER_LAST;
}
+ s->cpu_update_notifier.notify = arm_gicv3_cpu_update_notifier;
+
s->itslist = g_ptr_array_new();
}
@@ -495,6 +546,7 @@ static void arm_gicv3_finalize(Object *obj)
{
GICv3State *s = ARM_GICV3_COMMON(obj);
+ notifier_remove(&s->cpu_update_notifier);
g_free(s->redist_region_count);
}
diff --git a/hw/intc/arm_gicv3_cpuif_common.c b/hw/intc/arm_gicv3_cpuif_common.c
index ff1239f65d..381cf2754b 100644
--- a/hw/intc/arm_gicv3_cpuif_common.c
+++ b/hw/intc/arm_gicv3_cpuif_common.c
@@ -20,3 +20,8 @@ void gicv3_set_gicv3state(CPUState *cpu, GICv3CPUState *s)
env->gicv3state = (void *)s;
};
+
+void gicv3_set_cpustate(GICv3CPUState *s, CPUState *cpu)
+{
+ s->cpu = cpu;
+}
diff --git a/hw/intc/gicv3_internal.h b/hw/intc/gicv3_internal.h
index bc9f518fe8..42441c19c6 100644
--- a/hw/intc/gicv3_internal.h
+++ b/hw/intc/gicv3_internal.h
@@ -861,5 +861,6 @@ static inline void gicv3_cache_all_target_cpustates(GICv3State *s)
}
void gicv3_set_gicv3state(CPUState *cpu, GICv3CPUState *s);
+void gicv3_set_cpustate(GICv3CPUState *s, CPUState *cpu);
#endif /* QEMU_ARM_GICV3_INTERNAL_H */
diff --git a/include/hw/arm/virt.h b/include/hw/arm/virt.h
index d711cab46d..9c728ba042 100644
--- a/include/hw/arm/virt.h
+++ b/include/hw/arm/virt.h
@@ -181,6 +181,7 @@ struct VirtMachineState {
char *oem_id;
char *oem_table_id;
bool ns_el2_virt_timer_irq;
+ NotifierList cpuhp_notifiers;
};
#define VIRT_ECAM_ID(high) (high ? VIRT_HIGH_PCIE_ECAM : VIRT_PCIE_ECAM)
diff --git a/include/hw/intc/arm_gicv3_common.h b/include/hw/intc/arm_gicv3_common.h
index cd09bee3bc..496b198016 100644
--- a/include/hw/intc/arm_gicv3_common.h
+++ b/include/hw/intc/arm_gicv3_common.h
@@ -293,6 +293,7 @@ struct GICv3State {
GICv3CPUState *gicd_irouter_target[GICV3_MAXIRQ];
uint32_t gicd_nsacr[DIV_ROUND_UP(GICV3_MAXIRQ, 16)];
+ Notifier cpu_update_notifier;
GICv3CPUState *cpu;
/* List of all ITSes connected to this GIC */
GPtrArray *itslist;
@@ -342,6 +343,27 @@ struct ARMGICv3CommonClass {
void gicv3_init_irqs_and_mmio(GICv3State *s, qemu_irq_handler handler,
const MemoryRegionOps *ops);
+/**
+ * Structure used by GICv3 CPU hotplug notifier
+ */
+typedef struct GICv3CPUHotplugInfo {
+ DeviceState *gic; /* GICv3State */
+ CPUState *cpu;
+} GICv3CPUHotplugInfo;
+
+/**
+ * gicv3_cpuhp_notifier
+ *
+ * Returns CPU hotplug notifier which could be used to update GIC about any
+ * CPU hot(un)plug events.
+ *
+ * Returns: Notifier initialized with CPU Hot(un)plug update function
+ */
+static inline Notifier *gicv3_cpuhp_notifier(DeviceState *dev)
+{
+ GICv3State *s = ARM_GICV3_COMMON(dev);
+ return &s->cpu_update_notifier;
+}
/**
* gicv3_class_name
--
2.34.1