Re: [RFC 4/7] KVM: MMU: Refactor pkr_mask to cache condition

[Chenyi Qiang]

On 1/27/2021 2:16 AM, Paolo Bonzini wrote:
> On 07/08/20 10:48, Chenyi Qiang wrote:
> >          * index of the protection domain, so pte_pkey * 2 is
> >          * is the index of the first bit for the domain.
> >          */
> > -        pkr_bits = (vcpu->arch.pkru >> (pte_pkey * 2)) & 3;
> > +        if (pte_access & PT_USER_MASK)
> > +            pkr_bits = (vcpu->arch.pkru >> (pte_pkey * 2)) & 3;
> > +        else
> > +            pkr_bits = 0;
> >
> > -        /* clear present bit, replace PFEC.RSVD with ACC_USER_MASK. */
> > -        offset = (pfec & ~1) +
> > -            ((pte_access & PT_USER_MASK) << (PFERR_RSVD_BIT - 
> > PT_USER_SHIFT));
> > +        /* clear present bit */
> > +        offset = (pfec & ~1);
> >
> >          pkr_bits &= mmu->pkr_mask >> offset;
> >          errcode |= -pkr_bits & PFERR_PK_MASK;
>
> I think this is incorrect.  mmu->pkr_mask must cover both clear and set 
> ACC_USER_MASK, in to cover all combinations of CR4.PKE and CR4.PKS. 
> Right now, check_pkey is !ff && pte_user, but you need to make it 
> something like
>
>      check_pkey = !ff && (pte_user ? cr4_pke : cr4_pks);
>
> Paolo

Oh, I didn't distinguish the cr4_pke/cr4_pks check. Will fix this issue.

>