[RFC PATCH v7 14/28] KVM: arm64: Add SPE VCPU device attribute to initialize SPE
Alexandru Elisei
alexandru.elisei at arm.com
Thu Sep 3 09:06:09 PDT 2026
Add KVM_ARM_VCPU_SPE_CTRL(KVM_ARM_VCPU_SPE_INIT) VCPU ioctl to initialize
SPE. Initialization must be done exactly once for each VCPU.
[ Alexandru E: Split from "KVM: arm64: Add a new VCPU device control group
for SPE" ]
Signed-off-by: Sudeep Holla <sudeep.holla at arm.com>
Signed-off-by: Alexandru Elisei <alexandru.elisei at arm.com>
---
Documentation/virt/kvm/devices/vcpu.rst | 28 ++++++++++++++++++++---
arch/arm64/include/asm/kvm_spe.h | 6 +++++
arch/arm64/include/uapi/asm/kvm.h | 1 +
arch/arm64/kvm/arm.c | 6 +++++
arch/arm64/kvm/spe.c | 30 +++++++++++++++++++++++++
5 files changed, 68 insertions(+), 3 deletions(-)
diff --git a/Documentation/virt/kvm/devices/vcpu.rst b/Documentation/virt/kvm/devices/vcpu.rst
index d60dd1daa67f..e2eac48b9d28 100644
--- a/Documentation/virt/kvm/devices/vcpu.rst
+++ b/Documentation/virt/kvm/devices/vcpu.rst
@@ -317,6 +317,7 @@ From the destination VMM process:
Returns:
======= ==========================================================
+ -EBUSY SPE already initialized
-EFAULT Error accessing the buffer management interrupt number
-EINVAL Invalid interrupt number or not using an in-kernel irqchip
-ENODEV KVM_ARM_VCPU_HAS_SPE VCPU feature not set
@@ -338,15 +339,15 @@ vGIC implementation.
:Returns:
- ======= =========================================================
- -EBUSY Virtual machine has already run
+ ======= ===========================================================
+ -EBUSY Virtual machine has already run, or SPE already initialized
-EFAULT Error accessing the SPE identifier
-EINVAL A different SPE instance already assigned, or no physical
CPUs found
-ENXIO SPE not supported or not properly configured, or the SPE
module not loaded
-ENODEV KVM_ARM_VCPU_HAS_SPE VCPU feature not set
- ======= =========================================================
+ ======= ===========================================================
Required.
@@ -361,3 +362,24 @@ responsible for making sure that the VCPU is run only on physical CPUs which
share the specified SPE instance. If the VCPU has a PMU assigned, and there are
no physical CPUs which share the same SPE and PMU instance, an error is
returned.
+
+5.3 ATTRIBUTE: KVM_ARM_VCPU_SPE_INIT
+-----------------------------------
+
+:Parameters: no additional parameter in kvm_device_attr.addr
+
+Returns:
+
+ ======= ============================================
+ -EBUSY SPE already initialized for this VCPU
+ -ENXIO SPE not supported or not properly configured
+ ======= ============================================
+
+Required.
+
+Request initialization of the Statistical Profiling Extension for this VCPU.
+Must be done last, after SPE has been fully configured for the VCPU, and after
+the in-kernel irqchip has been initialized.
+
+KVM will refuse to run the VCPU and KVM_RUN will return an error if the SPE
+feature has been set for the VCPU, but SPE hasn't been initialized.
diff --git a/arch/arm64/include/asm/kvm_spe.h b/arch/arm64/include/asm/kvm_spe.h
index b8afb419c851..a6999709b298 100644
--- a/arch/arm64/include/asm/kvm_spe.h
+++ b/arch/arm64/include/asm/kvm_spe.h
@@ -18,6 +18,7 @@ struct kvm_spe {
struct kvm_vcpu_spe {
int irq_num; /* Buffer management interrupt number */
+ bool initialized; /* SPE initialized for the VCPU */
};
bool kvm_supports_spe(void);
@@ -25,6 +26,7 @@ bool kvm_supports_spe(void);
#define vcpu_has_spe(vcpu) \
(vcpu_has_feature(vcpu, KVM_ARM_VCPU_SPE))
+int kvm_spe_vcpu_first_run_init(struct kvm_vcpu *vcpu);
void kvm_spe_destroy_vm(struct kvm *kvm);
int kvm_spe_set_attr(struct kvm_vcpu *vcpu, struct kvm_device_attr *attr);
@@ -46,6 +48,10 @@ static __always_inline bool kvm_supports_spe(void)
#define vcpu_has_spe(vcpu) false
+static inline int kvm_spe_vcpu_first_run_init(struct kvm_vcpu *vcpu)
+{
+ return 0;
+}
static inline void kvm_spe_destroy_vm(struct kvm *kvm)
{
}
diff --git a/arch/arm64/include/uapi/asm/kvm.h b/arch/arm64/include/uapi/asm/kvm.h
index 8ffa3e89d38c..c695aae484d3 100644
--- a/arch/arm64/include/uapi/asm/kvm.h
+++ b/arch/arm64/include/uapi/asm/kvm.h
@@ -449,6 +449,7 @@ enum {
#define KVM_ARM_VCPU_SPE_CTRL 3
#define KVM_ARM_VCPU_SPE_IRQ 0
#define KVM_ARM_VCPU_SPE_ID 1
+#define KVM_ARM_VCPU_SPE_INIT 2
/* KVM_IRQ_LINE irq field index values */
#define KVM_ARM_IRQ_VCPU2_SHIFT 28
diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c
index 132df44c3088..c9a026c61ce7 100644
--- a/arch/arm64/kvm/arm.c
+++ b/arch/arm64/kvm/arm.c
@@ -1026,6 +1026,12 @@ int kvm_arch_vcpu_run_pid_change(struct kvm_vcpu *vcpu)
return ret;
}
+ if (vcpu_has_spe(vcpu)) {
+ ret = kvm_spe_vcpu_first_run_init(vcpu);
+ if (ret)
+ return ret;
+ }
+
ret = vgic_v5_finalize_ppi_state(kvm);
if (ret)
return ret;
diff --git a/arch/arm64/kvm/spe.c b/arch/arm64/kvm/spe.c
index 87fcdbbcbd67..fa87d224c8af 100644
--- a/arch/arm64/kvm/spe.c
+++ b/arch/arm64/kvm/spe.c
@@ -59,6 +59,16 @@ bool kvm_supports_spe(void)
return !list_empty(&spe_pmus);
}
+int kvm_spe_vcpu_first_run_init(struct kvm_vcpu *vcpu)
+{
+ struct kvm_vcpu_spe *vcpu_spe = &vcpu->arch.vcpu_spe;
+
+ if (!vcpu_spe->initialized)
+ return -EINVAL;
+
+ return 0;
+}
+
void kvm_spe_destroy_vm(struct kvm *kvm)
{
struct arm_spe_pmu *spe_pmu;
@@ -147,12 +157,16 @@ int kvm_spe_set_attr(struct kvm_vcpu *vcpu, struct kvm_device_attr *attr)
{
struct kvm_vcpu_spe *vcpu_spe = &vcpu->arch.vcpu_spe;
struct kvm *kvm = vcpu->kvm;
+ struct kvm_spe *kvm_spe = &kvm->arch.kvm_spe;
lockdep_assert_held(&kvm->arch.config_lock);
if (!vcpu_has_spe(vcpu))
return -ENODEV;
+ if (vcpu_spe->initialized)
+ return -EBUSY;
+
switch (attr->attr) {
case KVM_ARM_VCPU_SPE_IRQ: {
int __user *uaddr = (int __user *)(long)attr->addr;
@@ -182,6 +196,21 @@ int kvm_spe_set_attr(struct kvm_vcpu *vcpu, struct kvm_device_attr *attr)
return kvm_spe_set_spe_id(vcpu, spe_id);
}
+ case KVM_ARM_VCPU_SPE_INIT:
+ if (!vcpu_spe->irq_num)
+ return -ENXIO;
+
+ if (!kvm_spe->spe_pmu)
+ return -ENXIO;
+
+ if (!vgic_initialized(kvm))
+ return -ENXIO;
+
+ if (kvm_vgic_set_owner(vcpu, vcpu_spe->irq_num, vcpu_spe))
+ return -ENXIO;
+
+ vcpu_spe->initialized = true;
+ return 0;
}
return -ENXIO;
@@ -240,6 +269,7 @@ int kvm_spe_has_attr(struct kvm_vcpu *vcpu, struct kvm_device_attr *attr)
switch(attr->attr) {
case KVM_ARM_VCPU_SPE_IRQ:
case KVM_ARM_VCPU_SPE_ID:
+ case KVM_ARM_VCPU_SPE_INIT:
return 0;
}
--
2.43.0
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