Re: [PATCH v6 25/43] arm64: Don't expose stolen time for realm guests
From: Gavin Shan <hidden>
Date: 2025-02-02 02:16:03
Also in:
kvm, kvmarm, linux-coco, lkml
On 12/13/24 1:55 AM, Steven Price wrote:
quoted hunk ↗ jump to hunk
It doesn't make much sense as a realm guest wouldn't want to trust the host. It will also need some extra work to ensure that KVM will only attempt to write into a shared memory region. So for now just disable it. Reviewed-by: Suzuki K Poulose <suzuki.poulose@arm.com> Signed-off-by: Steven Price <steven.price@arm.com> --- arch/arm64/kvm/arm.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-)diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c index eff1a4ec892b..134acb4ee26f 100644 --- a/arch/arm64/kvm/arm.c +++ b/arch/arm64/kvm/arm.c@@ -432,7 +432,10 @@ 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(); + if (kvm_is_realm(kvm)) + r = 0; + else + r = kvm_arm_pvtime_supported(); break;
kvm_vm_ioctl_check_extension() can be called on the file descriptor of "/dev/kvm". 'kvm' is NULL and kvm_is_realm() returns false, which is the missed corner case.
case KVM_CAP_ARM_EL1_32BIT: r = cpus_have_final_cap(ARM64_HAS_32BIT_EL1);
Thanks, Gavin