[PATCH v4 04/18] KVM: arm64: Disable steal time for protected VMs

[Fuad Tabba <fuad.tabba@linux.dev>]

pKVM doesn't support steal time for protected guests, and
KVM_CAP_STEAL_TIME already reads 0 for them on the VM file descriptor,
but kvm_arm_pvtime_supported() takes no VM, so the host still
accepts the KVM_ARM_VCPU_PVTIME_CTRL attribute, whose IPA would point
kvm_update_stolen_time() at the guest's private memory on every vCPU
load. Pass the VM in and return false for a protected one, so the
attribute returns -ENXIO as it does where steal time isn't implemented.

Reviewed-by: Vincent Donnefort <vdonnefort@google.com>
Signed-off-by: Fuad Tabba <fuad.tabba@linux.dev>
---
 arch/arm64/include/asm/kvm_host.h |  2 +-
 arch/arm64/kvm/arm.c              |  2 +-
 arch/arm64/kvm/pvtime.c           | 10 +++++-----
 3 files changed, 7 insertions(+), 7 deletions(-)

diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
index 27fe0cd5b2d7a..286489a69dff5 100644
--- a/arch/arm64/include/asm/kvm_host.h
+++ b/arch/arm64/include/asm/kvm_host.h
@@ -1346,7 +1346,7 @@ long kvm_hypercall_pv_features(struct kvm_vcpu *vcpu);
 gpa_t kvm_init_stolen_time(struct kvm_vcpu *vcpu);
 void kvm_update_stolen_time(struct kvm_vcpu *vcpu);
 
-bool kvm_arm_pvtime_supported(void);
+bool kvm_arm_pvtime_supported(struct kvm *kvm);
 int kvm_arm_pvtime_set_attr(struct kvm_vcpu *vcpu,
 			    struct kvm_device_attr *attr);
 int kvm_arm_pvtime_get_attr(struct kvm_vcpu *vcpu,
diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c
index 8b080804bc90b..db36815630790 100644
--- a/arch/arm64/kvm/arm.c
+++ b/arch/arm64/kvm/arm.c
@@ -447,7 +447,7 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext)
 		r = system_supports_mte();
 		break;
 	case KVM_CAP_STEAL_TIME:
-		r = kvm_arm_pvtime_supported();
+		r = kvm_arm_pvtime_supported(kvm);
 		break;
 	case KVM_CAP_ARM_EL1_32BIT:
 		r = cpus_have_final_cap(ARM64_HAS_32BIT_EL1);
diff --git a/arch/arm64/kvm/pvtime.c b/arch/arm64/kvm/pvtime.c
index 4ceabaa4c30bd..053fe831fa541 100644
--- a/arch/arm64/kvm/pvtime.c
+++ b/arch/arm64/kvm/pvtime.c
@@ -67,9 +67,9 @@ gpa_t kvm_init_stolen_time(struct kvm_vcpu *vcpu)
 	return base;
 }
 
-bool kvm_arm_pvtime_supported(void)
+bool kvm_arm_pvtime_supported(struct kvm *kvm)
 {
-	return !!sched_info_on();
+	return !!sched_info_on() && (!kvm || !kvm_vm_is_protected(kvm));
 }
 
 int kvm_arm_pvtime_set_attr(struct kvm_vcpu *vcpu,
@@ -81,7 +81,7 @@ int kvm_arm_pvtime_set_attr(struct kvm_vcpu *vcpu,
 	int ret = 0;
 	int idx;
 
-	if (!kvm_arm_pvtime_supported() ||
+	if (!kvm_arm_pvtime_supported(kvm) ||
 	    attr->attr != KVM_ARM_VCPU_PVTIME_IPA)
 		return -ENXIO;
 
@@ -110,7 +110,7 @@ int kvm_arm_pvtime_get_attr(struct kvm_vcpu *vcpu,
 	u64 __user *user = (u64 __user *)attr->addr;
 	u64 ipa;
 
-	if (!kvm_arm_pvtime_supported() ||
+	if (!kvm_arm_pvtime_supported(vcpu->kvm) ||
 	    attr->attr != KVM_ARM_VCPU_PVTIME_IPA)
 		return -ENXIO;
 
@@ -126,7 +126,7 @@ int kvm_arm_pvtime_has_attr(struct kvm_vcpu *vcpu,
 {
 	switch (attr->attr) {
 	case KVM_ARM_VCPU_PVTIME_IPA:
-		if (kvm_arm_pvtime_supported())
+		if (kvm_arm_pvtime_supported(vcpu->kvm))
 			return 0;
 	}
 	return -ENXIO;
-- 
2.39.5