On Tue, Feb 02, 2021, Paolo Bonzini wrote:
> If not in long mode, the low bits of CR3 are reserved but not enforced to
> be zero, so remove those checks. If in long mode, however, the MBZ bits
> extend down to the highest physical address bit of the guest, excluding
> the encryption bit.
>
> Make the checks consistent with the above, and match them between
> nested_vmcb_checks and KVM_SET_SREGS.
>
Fixes + Cc:stable@?
> Signed-off-by: Paolo Bonzini <pbonzini@xxxxxxxxxx>
Reviewed-by: Sean Christopherson <seanjc@xxxxxxxxxx>
> ---
> arch/x86/kvm/svm/nested.c | 12 ++----------
> arch/x86/kvm/svm/svm.h | 3 ---
> arch/x86/kvm/x86.c | 2 ++
> 3 files changed, 4 insertions(+), 13 deletions(-)
>
> diff --git a/arch/x86/kvm/svm/nested.c b/arch/x86/kvm/svm/nested.c
> index eecb548bdda6..9ee542ea3f56 100644
> --- a/arch/x86/kvm/svm/nested.c
> +++ b/arch/x86/kvm/svm/nested.c
> @@ -244,18 +244,10 @@ static bool nested_vmcb_checks(struct vcpu_svm *svm, struct vmcb *vmcb12)
>
> vmcb12_lma = (vmcb12->save.efer & EFER_LME) && (vmcb12->save.cr0 & X86_CR0_PG);
>
> - if (!vmcb12_lma) {
> - if (vmcb12->save.cr4 & X86_CR4_PAE) {
> - if (vmcb12->save.cr3 & MSR_CR3_LEGACY_PAE_RESERVED_MASK)
> - return false;
> - } else {
> - if (vmcb12->save.cr3 & MSR_CR3_LEGACY_RESERVED_MASK)
> - return false;
> - }
> - } else {
> + if (vmcb12_lma) {
> if (!(vmcb12->save.cr4 & X86_CR4_PAE) ||
> !(vmcb12->save.cr0 & X86_CR0_PE) ||
> - (vmcb12->save.cr3 & MSR_CR3_LONG_MBZ_MASK))
> + (vmcb12->save.cr3 & svm->vcpu.arch.cr3_lm_rsvd_bits))
Gah, I was too slow as usual. I have a series to clean up GPA validity checks,
this one included. I'll base that series on this patch, if I get it sent before
this hits kvm/queue...
> return false;
> }
> if (!kvm_is_valid_cr4(&svm->vcpu, vmcb12->save.cr4))
> diff --git a/arch/x86/kvm/svm/svm.h b/arch/x86/kvm/svm/svm.h
> index 0fe874ae5498..6e7d070f8b86 100644
> --- a/arch/x86/kvm/svm/svm.h
> +++ b/arch/x86/kvm/svm/svm.h
> @@ -403,9 +403,6 @@ static inline bool gif_set(struct vcpu_svm *svm)
> }
>
> /* svm.c */
> -#define MSR_CR3_LEGACY_RESERVED_MASK 0xfe7U
> -#define MSR_CR3_LEGACY_PAE_RESERVED_MASK 0x7U
> -#define MSR_CR3_LONG_MBZ_MASK 0xfff0000000000000U
> #define MSR_INVALID 0xffffffffU
>
> extern int sev;
> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> index b748bf0d6d33..97674204bf44 100644
> --- a/arch/x86/kvm/x86.c
> +++ b/arch/x86/kvm/x86.c
> @@ -9660,6 +9660,8 @@ static bool kvm_is_valid_sregs(struct kvm_vcpu *vcpu, struct kvm_sregs *sregs)
> */
> if (!(sregs->cr4 & X86_CR4_PAE) || !(sregs->efer & EFER_LMA))
> return false;
> + if (sregs->cr3 & vcpu->arch.cr3_lm_rsvd_bits)
> + return false;
> } else {
> /*
> * Not in 64-bit mode: EFER.LMA is clear and the code
> --
> 2.26.2
>
