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SubjectRe: [PATCH 03/16] KVM: x86: Define more SEV+ page fault error bits/flags for #NPF
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On 2/27/24 18:41, Sean Christopherson wrote:
> Define more #NPF error code flags that are relevant to SEV+ (mostly SNP)
> guests, as specified by the APM:
>
> * Bit 34 (ENC): Set to 1 if the guest’s effective C-bit was 1, 0 otherwise.
> * Bit 35 (SIZEM): Set to 1 if the fault was caused by a size mismatch between
> PVALIDATE or RMPADJUST and the RMP, 0 otherwise.
> * Bit 36 (VMPL): Set to 1 if the fault was caused by a VMPL permission
> check failure, 0 otherwise.
> * Bit 37 (SSS): Set to VMPL permission mask SSS (bit 4) value if VmplSSS is
> enabled.

The above bits 34-37 do not match with the bits 31,34-36 in the patch.

Dongli Zhang

>
> Note, the APM is *extremely* misleading, and strongly implies that the
> above flags can _only_ be set for #NPF exits from SNP guests. That is a
> lie, as bit 34 (C-bit=1, i.e. was encrypted) can be set when running _any_
> flavor of SEV guest on SNP capable hardware.
>
> Signed-off-by: Sean Christopherson <seanjc@google.com>
> ---
> arch/x86/include/asm/kvm_host.h | 4 ++++
> 1 file changed, 4 insertions(+)
>
> diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
> index 88cc523bafa8..1e69743ef0fb 100644
> --- a/arch/x86/include/asm/kvm_host.h
> +++ b/arch/x86/include/asm/kvm_host.h
> @@ -261,8 +261,12 @@ enum x86_intercept_stage;
> #define PFERR_FETCH_MASK BIT(4)
> #define PFERR_PK_MASK BIT(5)
> #define PFERR_SGX_MASK BIT(15)
> +#define PFERR_GUEST_RMP_MASK BIT_ULL(31)
> #define PFERR_GUEST_FINAL_MASK BIT_ULL(32)
> #define PFERR_GUEST_PAGE_MASK BIT_ULL(33)
> +#define PFERR_GUEST_ENC_MASK BIT_ULL(34)
> +#define PFERR_GUEST_SIZEM_MASK BIT_ULL(35)
> +#define PFERR_GUEST_VMPL_MASK BIT_ULL(36)
> #define PFERR_IMPLICIT_ACCESS BIT_ULL(48)
>
> #define PFERR_NESTED_GUEST_PAGE (PFERR_GUEST_PAGE_MASK | \

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