[RFC PATCH v6 11/35] KVM: arm64: Add SPE VCPU device attribute to set the interrupt number

Alexandru Elisei
2025-11-14T16:08:02Z

From: Sudeep Holla <sudeep.holla@arm.com>

Add KVM_ARM_VCPU_SPE_CTRL(KVM_ARM_VCPU_SPE_IRQ) to allow the user to set
the interrupt number for the buffer management interrupt.

[ Alexandru E: Split from "KVM: arm64: Add a new VCPU device control group
for SPE" ]

Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>
Signed-off-by: Alexandru Elisei <alexandru.elisei@arm.com>
---
Documentation/virt/kvm/devices/vcpu.rst | 22 +++++++
arch/arm64/include/asm/kvm_host.h | 2 +
arch/arm64/include/asm/kvm_spe.h | 10 +++
arch/arm64/include/uapi/asm/kvm.h | 1 +
arch/arm64/kvm/guest.c | 2 +
arch/arm64/kvm/spe.c | 82 +++++++++++++++++++++++++
6 files changed, 119 insertions(+)

diff --git a/Documentation/virt/kvm/devices/vcpu.rst b/Documentation/virt/kvm/devices/vcpu.rst
index 8c5208ccd107..9a26252d0a34 100644
--- a/Documentation/virt/kvm/devices/vcpu.rst
+++ b/Documentation/virt/kvm/devices/vcpu.rst
@@ -296,3 +296,25 @@ From the destination VMM process:
===============================

:Architectures: ARM64
+
+5.1 ATTRIBUTE: KVM_ARM_VCPU_SPE_IRQ
+-----------------------------------
+
+:Parameters: in kvm_device_attr.addr the address for the Profiling Buffer
+ management interrupt number as a pointer to an int
+
+Returns:
+
+ ======= ==========================================================
+ -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
+ -ENXIO SPE not supported or not properly configured
+ ======= ==========================================================
+
+Required.
+
+Specifies the Profiling Buffer management interrupt number. The interrupt number
+must be a PPI and the interrupt number must be the same for each VCPU. Arm
+recommends 21 as the interrupt number. SPE virtualization requires an in-kernel
+vGIC implementation.
diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
index 64302c438355..bc7aeae39fb9 100644
--- a/arch/arm64/include/asm/kvm_host.h
+++ b/arch/arm64/include/asm/kvm_host.h
@@ -27,6 +27,7 @@
#include <asm/fpsimd.h>
#include <asm/kvm.h>
#include <asm/kvm_asm.h>
+#include <asm/kvm_spe.h>
#include <asm/vncr_mapping.h>

#define __KVM_HAVE_ARCH_INTC_INITIALIZED
@@ -865,6 +866,7 @@ struct kvm_vcpu_arch {
struct vgic_cpu vgic_cpu;
struct arch_timer_cpu timer_cpu;
struct kvm_pmu pmu;
+ struct kvm_vcpu_spe vcpu_spe;

/* vcpu power state */
struct kvm_mp_state mp_state;
diff --git a/arch/arm64/include/asm/kvm_spe.h b/arch/arm64/include/asm/kvm_spe.h
index 7c8268f6f507..6855976b4c72 100644
--- a/arch/arm64/include/asm/kvm_spe.h
+++ b/arch/arm64/include/asm/kvm_spe.h
@@ -6,7 +6,14 @@
#ifndef __ARM64_KVM_SPE_H__
#define __ARM64_KVM_SPE_H__

+#include <linux/kvm.h>
+
#ifdef CONFIG_KVM_ARM_SPE
+
+struct kvm_vcpu_spe {
+ int irq_num; /* Buffer management interrupt number */
+};
+
DECLARE_STATIC_KEY_FALSE(kvm_spe_available);

static __always_inline bool kvm_supports_spe(void)
@@ -21,6 +28,9 @@ int kvm_spe_set_attr(struct kvm_vcpu *vcpu, struct kvm_device_attr *attr);
int kvm_spe_get_attr(struct kvm_vcpu *vcpu, struct kvm_device_attr *attr);
int kvm_spe_has_attr(struct kvm_vcpu *vcpu, struct kvm_device_attr *attr);
#else
+struct kvm_vcpu_spe {
+};
+
#define kvm_supports_spe() false
#define vcpu_has_spe(vcpu) false

diff --git a/arch/arm64/include/uapi/asm/kvm.h b/arch/arm64/include/uapi/asm/kvm.h
index 5e2d47572136..578a0f6c3f8f 100644
--- a/arch/arm64/include/uapi/asm/kvm.h
+++ b/arch/arm64/include/uapi/asm/kvm.h
@@ -445,6 +445,7 @@ enum {
#define KVM_ARM_VCPU_PVTIME_CTRL 2
#define KVM_ARM_VCPU_PVTIME_IPA 0
#define KVM_ARM_VCPU_SPE_CTRL 3
+#define KVM_ARM_VCPU_SPE_IRQ 0

/* KVM_IRQ_LINE irq field index values */
#define KVM_ARM_IRQ_VCPU2_SHIFT 28
diff --git a/arch/arm64/kvm/guest.c b/arch/arm64/kvm/guest.c
index d1bf8b154a31..fbc17a71edc3 100644
--- a/arch/arm64/kvm/guest.c
+++ b/arch/arm64/kvm/guest.c
@@ -920,7 +920,9 @@ int kvm_arm_vcpu_arch_set_attr(struct kvm_vcpu *vcpu,
ret = kvm_arm_pvtime_set_attr(vcpu, attr);
break;
case KVM_ARM_VCPU_SPE_CTRL:
+ mutex_lock(&vcpu->kvm->arch.config_lock);
ret = kvm_spe_set_attr(vcpu, attr);
+ mutex_unlock(&vcpu->kvm->arch.config_lock);
break;
default:
ret = -ENXIO;
diff --git a/arch/arm64/kvm/spe.c b/arch/arm64/kvm/spe.c
index 4d635e881620..c6b81a2ef71f 100644
--- a/arch/arm64/kvm/spe.c
+++ b/arch/arm64/kvm/spe.c
@@ -41,17 +41,99 @@ void kvm_host_spe_init(struct arm_spe_pmu *arm_spu)
static_branch_enable(&kvm_spe_available);
}

+static bool kvm_spe_irq_is_valid(struct kvm *kvm, int irq)
+{
+ struct kvm_vcpu *vcpu;
+ struct kvm_vcpu_spe *vcpu_spe;
+ unsigned long i;
+
+ kvm_for_each_vcpu(i, vcpu, kvm) {
+ vcpu_spe = &vcpu->arch.vcpu_spe;
+
+ if (!vcpu_spe->irq_num)
+ continue;
+
+ if (vcpu_spe->irq_num != irq)
+ return false;
+ }
+
+ return true;
+}
+
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;
+
+ lockdep_assert_held(&kvm->arch.config_lock);
+
+ if (!vcpu_has_spe(vcpu))
+ return -ENODEV;
+
+ switch (attr->attr) {
+ case KVM_ARM_VCPU_SPE_IRQ: {
+ int __user *uaddr = (int __user *)(long)attr->addr;
+ int irq;
+
+ if (!irqchip_in_kernel(kvm))
+ return -EINVAL;
+
+ if (get_user(irq, uaddr))
+ return -EFAULT;
+
+ if (!irq_is_ppi(irq))
+ return -EINVAL;
+
+ if (!kvm_spe_irq_is_valid(kvm, irq))
+ return -EINVAL;
+
+ vcpu_spe->irq_num = irq;
+ return 0;
+ }
+ }
+
return -ENXIO;
}

int kvm_spe_get_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;
+
+ if (!vcpu_has_spe(vcpu))
+ return -ENODEV;
+
+ switch (attr->attr) {
+ case KVM_ARM_VCPU_SPE_IRQ: {
+ int __user *uaddr = (int __user *)(long)attr->addr;
+ int irq;
+
+ if (!irqchip_in_kernel(kvm))
+ return -EINVAL;
+
+ if (!vcpu_spe->irq_num)
+ return -ENXIO;
+
+ irq = vcpu_spe->irq_num;
+ if (put_user(irq, uaddr))
+ return -EFAULT;
+
+ return 0;
+ }
+ }
+
return -ENXIO;
}

int kvm_spe_has_attr(struct kvm_vcpu *vcpu, struct kvm_device_attr *attr)
{
+ if (!vcpu_has_spe(vcpu))
+ return -ENODEV;
+
+ switch(attr->attr) {
+ case KVM_ARM_VCPU_SPE_IRQ:
+ return 0;
+ }
+
return -ENXIO;
}
--
2.51.2