KVM: arm64: Use KVM extension checks for allowed protected VM capabilities

Use KVM extension checks as the source for determining which
capabilities are allowed for protected VMs. KVM extension checks
is the natural place for this, since it is also the interface
exposed to users.

Signed-off-by: Fuad Tabba <tabba@google.com>
Link: https://lore.kernel.org/r/20241216105057.579031-6-tabba@google.com
Signed-off-by: Marc Zyngier <maz@kernel.org>

diff --git a/arch/arm64/include/asm/kvm_pkvm.h b/arch/arm64/include/asm/kvm_pkvm.h
index cd56acd9a842ccfaaa486cb4fef22e3777b90172..400f7cef1e81b29925ed00593d8198f8d2700025 100644 (file)
--- a/arch/arm64/include/asm/kvm_pkvm.h
+++ b/arch/arm64/include/asm/kvm_pkvm.h
@@ -20,6 +20,31 @@ int pkvm_init_host_vm(struct kvm *kvm);
 int pkvm_create_hyp_vm(struct kvm *kvm);
 void pkvm_destroy_hyp_vm(struct kvm *kvm);
 
+/*
+ * This functions as an allow-list of protected VM capabilities.
+ * Features not explicitly allowed by this function are denied.
+ */
+static inline bool kvm_pvm_ext_allowed(long ext)
+{
+       switch (ext) {
+       case KVM_CAP_IRQCHIP:
+       case KVM_CAP_ARM_PSCI:
+       case KVM_CAP_ARM_PSCI_0_2:
+       case KVM_CAP_NR_VCPUS:
+       case KVM_CAP_MAX_VCPUS:
+       case KVM_CAP_MAX_VCPU_ID:
+       case KVM_CAP_MSI_DEVID:
+       case KVM_CAP_ARM_VM_IPA_SIZE:
+       case KVM_CAP_ARM_PMU_V3:
+       case KVM_CAP_ARM_SVE:
+       case KVM_CAP_ARM_PTRAUTH_ADDRESS:
+       case KVM_CAP_ARM_PTRAUTH_GENERIC:
+               return true;
+       default:
+               return false;
+       }
+}
+
 extern struct memblock_region kvm_nvhe_sym(hyp_memory)[];
 extern unsigned int kvm_nvhe_sym(hyp_memblock_nr);
 

diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c
index a102c3aebdbc419fe94a0f973eb2b3f06f0ba698..b295218cdc24476c5035b7fcaf715f77334fe2f0 100644 (file)
--- a/arch/arm64/kvm/arm.c
+++ b/arch/arm64/kvm/arm.c
@@ -80,31 +80,6 @@ int kvm_arch_vcpu_should_kick(struct kvm_vcpu *vcpu)
        return kvm_vcpu_exiting_guest_mode(vcpu) == IN_GUEST_MODE;
 }
 
-/*
- * This functions as an allow-list of protected VM capabilities.
- * Features not explicitly allowed by this function are denied.
- */
-static bool pkvm_ext_allowed(struct kvm *kvm, long ext)
-{
-       switch (ext) {
-       case KVM_CAP_IRQCHIP:
-       case KVM_CAP_ARM_PSCI:
-       case KVM_CAP_ARM_PSCI_0_2:
-       case KVM_CAP_NR_VCPUS:
-       case KVM_CAP_MAX_VCPUS:
-       case KVM_CAP_MAX_VCPU_ID:
-       case KVM_CAP_MSI_DEVID:
-       case KVM_CAP_ARM_VM_IPA_SIZE:
-       case KVM_CAP_ARM_PMU_V3:
-       case KVM_CAP_ARM_SVE:
-       case KVM_CAP_ARM_PTRAUTH_ADDRESS:
-       case KVM_CAP_ARM_PTRAUTH_GENERIC:
-               return true;
-       default:
-               return false;
-       }
-}
-
 int kvm_vm_ioctl_enable_cap(struct kvm *kvm,
                            struct kvm_enable_cap *cap)
 {
@@ -113,7 +88,7 @@ int kvm_vm_ioctl_enable_cap(struct kvm *kvm,
        if (cap->flags)
                return -EINVAL;
 
-       if (kvm_vm_is_protected(kvm) && !pkvm_ext_allowed(kvm, cap->cap))
+       if (kvm_vm_is_protected(kvm) && !kvm_pvm_ext_allowed(cap->cap))
                return -EINVAL;
 
        switch (cap->cap) {
@@ -311,7 +286,7 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext)
 {
        int r;
 
-       if (kvm && kvm_vm_is_protected(kvm) && !pkvm_ext_allowed(kvm, ext))
+       if (kvm && kvm_vm_is_protected(kvm) && !kvm_pvm_ext_allowed(ext))
                return 0;
 
        switch (ext) {

diff --git a/arch/arm64/kvm/hyp/nvhe/pkvm.c b/arch/arm64/kvm/hyp/nvhe/pkvm.c
index d7ca7e9ccea2ee5638da1ad6dc033c1b3f201489..c39d4e92dd3cf875542c206e6bf1118323ec2421 100644 (file)
--- a/arch/arm64/kvm/hyp/nvhe/pkvm.c
+++ b/arch/arm64/kvm/hyp/nvhe/pkvm.c
@@ -329,32 +329,20 @@ static void pkvm_init_features_from_host(struct pkvm_hyp_vm *hyp_vm, const struc
 
        bitmap_zero(allowed_features, KVM_VCPU_MAX_FEATURES);
 
-       /*
-        * For protected VMs, always allow:
-        * - PSCI v0.2
-        */
        set_bit(KVM_ARM_VCPU_PSCI_0_2, allowed_features);
 
-       /*
-        * Check if remaining features are allowed:
-        * - Performance Monitoring
-        * - Scalable Vectors
-        * - Pointer Authentication
-        */
-       if (FIELD_GET(ARM64_FEATURE_MASK(ID_AA64DFR0_EL1_PMUVer), PVM_ID_AA64DFR0_ALLOW))
+       if (kvm_pvm_ext_allowed(KVM_CAP_ARM_PMU_V3))
                set_bit(KVM_ARM_VCPU_PMU_V3, allowed_features);
 
-       if (FIELD_GET(ARM64_FEATURE_MASK(ID_AA64PFR0_EL1_SVE), PVM_ID_AA64PFR0_ALLOW))
-               set_bit(KVM_ARM_VCPU_SVE, allowed_features);
-
-       if (FIELD_GET(ARM64_FEATURE_MASK(ID_AA64ISAR1_EL1_API), PVM_ID_AA64ISAR1_ALLOW) &&
-           FIELD_GET(ARM64_FEATURE_MASK(ID_AA64ISAR1_EL1_APA), PVM_ID_AA64ISAR1_ALLOW))
+       if (kvm_pvm_ext_allowed(KVM_CAP_ARM_PTRAUTH_ADDRESS))
                set_bit(KVM_ARM_VCPU_PTRAUTH_ADDRESS, allowed_features);
 
-       if (FIELD_GET(ARM64_FEATURE_MASK(ID_AA64ISAR1_EL1_GPI), PVM_ID_AA64ISAR1_ALLOW) &&
-           FIELD_GET(ARM64_FEATURE_MASK(ID_AA64ISAR1_EL1_GPA), PVM_ID_AA64ISAR1_ALLOW))
+       if (kvm_pvm_ext_allowed(KVM_CAP_ARM_PTRAUTH_GENERIC))
                set_bit(KVM_ARM_VCPU_PTRAUTH_GENERIC, allowed_features);
 
+       if (kvm_pvm_ext_allowed(KVM_CAP_ARM_SVE))
+               set_bit(KVM_ARM_VCPU_SVE, allowed_features);
+
        bitmap_and(kvm->arch.vcpu_features, host_kvm->arch.vcpu_features,
                   allowed_features, KVM_VCPU_MAX_FEATURES);
 }