On 12/12/2024 11:05 AM, Sean Christopherson wrote:
On Thu, Dec 12, 2024, Xin Li wrote:
On 10/24/2024 12:18 AM, Chao Gao wrote:
diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index 03f42b218554..bfdd10773136 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -8009,6 +8009,10 @@ void vmx_vcpu_after_set_cpuid(struct kvm_vcpu *vcpu)
kvm_governed_feature_check_and_set(vcpu, X86_FEATURE_LAM);
kvm_governed_feature_check_and_set(vcpu, X86_FEATURE_FRED);
+ /* Don't allow CR4.FRED=1 before all of FRED KVM support is in place. */
+ if (!guest_can_use(vcpu, X86_FEATURE_FRED))
+ vcpu->arch.cr4_guest_rsvd_bits |= X86_CR4_FRED;
is this necessary? __kvm_is_valid_cr4() ensures that guests cannot set any bit
which isn't supported by the hardware.
To account for hardware/KVM caps, I think the following changes will work. This
will fix all other bits besides X86_CR4_FRED.
This seems a generic infra improvement, maybe it's better for you to
send it as an individual patch to Sean and the KVM mailing list?
Already ahead of y'all :-) (I think, I didn't look closely at this).
https://lore.kernel.org/all/20241128013424.4096668-6-seanjc@xxxxxxxxxx
Ha, that is nice. Thank you!
