Re: [PATCH 02/16] KVM: x86: Remove separate "bit" defines for page fault error code masks

[Paolo Bonzini]

On Thu, Feb 29, 2024 at 7:40 PM Sean Christopherson <seanjc@xxxxxxxxxx> wrote:
> Long story short, I think we should get to the below (I'll post a separate series,
> assuming I'm not missing something).
>
>         unsigned long rflags = static_call(kvm_x86_get_rflags)(vcpu);
>         unsigned int pfec = access & (PFERR_PRESENT_MASK |
>                                       PFERR_WRITE_MASK |
>                                       PFERR_USER_MASK |
>                                       PFERR_FETCH_MASK);
>
>         /*
>          * For explicit supervisor accesses, SMAP is disabled if EFLAGS.AC = 1.
>          * For implicit supervisor accesses, SMAP cannot be overridden.
>          *
>          * SMAP works on supervisor accesses only, and not_smap can
>          * be set or not set when user access with neither has any bearing
>          * on the result.
>          *
>          * We put the SMAP checking bit in place of the PFERR_RSVD_MASK bit;
>          * this bit will always be zero in pfec, but it will be one in index
>          * if SMAP checks are being disabled.
>          */
>         u64 implicit_access = access & PFERR_IMPLICIT_ACCESS;
>         bool not_smap = ((rflags & X86_EFLAGS_AC) | implicit_access) == X86_EFLAGS_AC;
>         int index = (pfec | (not_smap ? PFERR_RSVD_MASK : 0)) >> 1;
>         u32 errcode = PFERR_PRESENT_MASK;
>         bool fault;

Sounds good.  The whole series is

Reviewed-by: Paolo Bonzini <pbonzini@xxxxxxxxxx>

apart from the small nits that were pointed out here and there.

Paolo