[PATCH v18 02/23] KVM: arm64: Disable Steal time accounting for protected guests
From: Suzuki K Poulose <suzuki.poulose@arm.com>
Date: 2026-09-15 16:01:59
Also in:
kvm, kvmarm, linux-coco, lkml
Subsystem:
arm64 port (aarch64 architecture), kernel virtual machine for arm64 (kvm/arm64), the rest · Maintainers:
Catalin Marinas, Will Deacon, Marc Zyngier, Oliver Upton, Linus Torvalds
PVTIME support is advertised by KVM_CAP_STEAL_TIME, which doesn't take into account the kvm instance. Even with that, a VMM could skip the CAP check and proceed to configure the PVTIME as we don't do further check on the DEVICE_CTRL. Tighten this up by passing the KVM instance around wherever possible and catch things early Reviewed-by: Fuad Tabba <fuad.tabba@linux.dev> Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com> --- arch/arm64/include/asm/kvm_host.h | 2 +- arch/arm64/kvm/arm.c | 2 +- arch/arm64/kvm/pvtime.c | 14 +++++++------- 3 files changed, 9 insertions(+), 9 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 7c88508cac8a1..3fbdfce926475 100644
--- a/arch/arm64/kvm/arm.c
+++ b/arch/arm64/kvm/arm.c@@ -462,7 +462,7 @@ 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..579e0a4720ad2 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,
@@ -81,8 +81,8 @@ int kvm_arm_pvtime_set_attr(struct kvm_vcpu *vcpu, int ret = 0; int idx; - if (!kvm_arm_pvtime_supported() || - attr->attr != KVM_ARM_VCPU_PVTIME_IPA) + if (!kvm_arm_pvtime_supported(kvm) || + (attr->attr != KVM_ARM_VCPU_PVTIME_IPA)) return -ENXIO; if (get_user(ipa, user))
@@ -110,8 +110,8 @@ int kvm_arm_pvtime_get_attr(struct kvm_vcpu *vcpu, u64 __user *user = (u64 __user *)attr->addr; u64 ipa; - if (!kvm_arm_pvtime_supported() || - attr->attr != KVM_ARM_VCPU_PVTIME_IPA) + if (!kvm_arm_pvtime_supported(vcpu->kvm) || + (attr->attr != KVM_ARM_VCPU_PVTIME_IPA)) return -ENXIO; ipa = vcpu->arch.steal.base;
@@ -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;
--
2.43.0