[PATCH v7 26/45] arm64: Don't expose stolen time for realm guests

Steven Price
2025-02-13T16:16:40Z

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 a6718dec00c9..79d541c95bfb 100644
--- a/arch/arm64/kvm/arm.c
+++ b/arch/arm64/kvm/arm.c
@@ -403,7 +403,10 @@ 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;
case KVM_CAP_ARM_EL1_32BIT:
r = cpus_have_final_cap(ARM64_HAS_32BIT_EL1);
--
2.43.0