[RFC PATCH v7 07/28] KVM: arm64: Add KVM_ARM_VCPU_SPE VCPU feature

[Alexandru Elisei]

Add a new VCPU feature that enables SPE virtualization when set by
userspace. KVM_VCPU_MAX_FEATURE will be bumped and the feature will
become selectable by userspace once SPE support in KVM is implemented.

Signed-off-by: Alexandru Elisei <alexandru.elisei at arm.com>
---
 Documentation/virt/kvm/api.rst    | 2 ++
 arch/arm64/include/asm/kvm_spe.h  | 5 +++++
 arch/arm64/include/uapi/asm/kvm.h | 1 +
 arch/arm64/kvm/arm.c              | 7 +++++++
 4 files changed, 15 insertions(+)

diff --git a/Documentation/virt/kvm/api.rst b/Documentation/virt/kvm/api.rst
index 1ed5c389c7a4..654736fac78c 100644
--- a/Documentation/virt/kvm/api.rst
+++ b/Documentation/virt/kvm/api.rst
@@ -3591,6 +3591,8 @@ Possible features:
 	  Depends on KVM_CAP_ARM_EL2_E2H0.
 	  KVM_ARM_VCPU_HAS_EL2 must also be set.
 
+        - KVM_ARM_VCPU_SPE: Enable SPE for the CPU. Depends on KVM_CAP_ARM_SPE.
+
 4.83 KVM_ARM_PREFERRED_TARGET
 -----------------------------
 
diff --git a/arch/arm64/include/asm/kvm_spe.h b/arch/arm64/include/asm/kvm_spe.h
index f05e6d3f5705..e452da82666d 100644
--- a/arch/arm64/include/asm/kvm_spe.h
+++ b/arch/arm64/include/asm/kvm_spe.h
@@ -8,11 +8,16 @@
 
 #ifdef CONFIG_KVM_ARM_SPE
 bool kvm_supports_spe(void);
+
+#define vcpu_has_spe(vcpu)					\
+	(vcpu_has_feature(vcpu, KVM_ARM_VCPU_SPE))
 #else
 static __always_inline bool kvm_supports_spe(void)
 {
 	return false;
 }
+
+#define vcpu_has_spe(vcpu)	false
 #endif /* CONFIG_KVM_ARM_SPE */
 
 #endif /* __ARM64_KVM_SPE_H__ */
diff --git a/arch/arm64/include/uapi/asm/kvm.h b/arch/arm64/include/uapi/asm/kvm.h
index 019e5e3d892e..f7f751c00e6f 100644
--- a/arch/arm64/include/uapi/asm/kvm.h
+++ b/arch/arm64/include/uapi/asm/kvm.h
@@ -107,6 +107,7 @@ struct kvm_regs {
 #define KVM_ARM_VCPU_HAS_EL2		7 /* Support nested virtualization */
 #define KVM_ARM_VCPU_HAS_EL2_E2H0	8 /* Limit NV support to E2H RES0 */
 #define KVM_ARM_VCPU_PMU_V3_STRICT	9 /* No default PMU creation */
+#define KVM_ARM_VCPU_SPE		10 /* Support SPE in guest */
 
 struct kvm_vcpu_init {
 	__u32 target;
diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c
index eca1184ef9dd..b9cee4cf293d 100644
--- a/arch/arm64/kvm/arm.c
+++ b/arch/arm64/kvm/arm.c
@@ -1604,6 +1604,9 @@ static unsigned long system_supported_vcpu_features(void)
 	if (!cpus_have_final_cap(ARM64_HAS_NESTED_VIRT))
 		clear_bit(KVM_ARM_VCPU_HAS_EL2, &features);
 
+	if (!kvm_supports_spe())
+		clear_bit(KVM_ARM_VCPU_SPE, &features);
+
 	return features;
 }
 
@@ -1648,6 +1651,10 @@ static int kvm_vcpu_init_check_features(struct kvm_vcpu *vcpu,
 	if (test_bit(KVM_ARM_VCPU_HAS_EL2, &features))
 		return -EINVAL;
 
+	/* SPE is incompatible with AArch32 */
+	if (test_bit(KVM_ARM_VCPU_SPE, &features))
+		return -EINVAL;
+
 	return 0;
 }
 
-- 
2.43.0