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SubjectRe: [PATCH v6 15/25] KVM: x86: Add fault checks for guest CR4.CET setting
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On Thu, 2023-09-14 at 02:33 -0400, Yang Weijiang wrote:
> Check potential faults for CR4.CET setting per Intel SDM requirements.
> CET can be enabled if and only if CR0.WP == 1, i.e. setting CR4.CET ==
> 1 faults if CR0.WP == 0 and setting CR0.WP == 0 fails if CR4.CET == 1.
>
> Reviewed-by: Chao Gao <chao.gao@intel.com>
> Co-developed-by: Sean Christopherson <seanjc@google.com>
> Signed-off-by: Sean Christopherson <seanjc@google.com>
> Signed-off-by: Yang Weijiang <weijiang.yang@intel.com>
> ---
> arch/x86/kvm/x86.c | 6 ++++++
> 1 file changed, 6 insertions(+)
>
> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> index a091764bf1d2..dda9c7141ea1 100644
> --- a/arch/x86/kvm/x86.c
> +++ b/arch/x86/kvm/x86.c
> @@ -1006,6 +1006,9 @@ int kvm_set_cr0(struct kvm_vcpu *vcpu, unsigned long cr0)
> (is_64_bit_mode(vcpu) || kvm_is_cr4_bit_set(vcpu, X86_CR4_PCIDE)))
> return 1;
>
> + if (!(cr0 & X86_CR0_WP) && kvm_is_cr4_bit_set(vcpu, X86_CR4_CET))
> + return 1;
> +
> static_call(kvm_x86_set_cr0)(vcpu, cr0);
>
> kvm_post_set_cr0(vcpu, old_cr0, cr0);
> @@ -1217,6 +1220,9 @@ int kvm_set_cr4(struct kvm_vcpu *vcpu, unsigned long cr4)
> return 1;
> }
>
> + if ((cr4 & X86_CR4_CET) && !kvm_is_cr0_bit_set(vcpu, X86_CR0_WP))
> + return 1;
> +
> static_call(kvm_x86_set_cr4)(vcpu, cr4);
>
> kvm_post_set_cr4(vcpu, old_cr4, cr4);

Reviewed-by: Maxim Levitsky <mlevitsk@redhat.com>

Best regards,
Maxim Levitsky




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