On Mon, 2016-03-21 at 11:55 +0100, Paolo Bonzini wrote:
>
> On 21/03/2016 11:05, Huaitong Han wrote:
> > static inline u8 permission_fault(struct kvm_vcpu *vcpu, struct kvm_mmu *mmu,
> > - unsigned pte_access, unsigned pfec)
> > + unsigned pte_access, unsigned pte_pkey,
> > + unsigned pfec)
> > {
> > int cpl = kvm_x86_ops->get_cpl(vcpu);
> > unsigned long rflags = kvm_x86_ops->get_rflags(vcpu);
> > + unsigned long smap = (cpl - 3) & (rflags & X86_EFLAGS_AC);
> > + int index = (pfec >> 1) +
> > + (smap >> (X86_EFLAGS_AC_BIT - PFERR_RSVD_BIT + 1));
> > +
> > + if (unlikely(mmu->pkru_mask)) {
> > + u32 pkru_bits, offset;
> > +
> > + WARN_ON(pfec & (PFERR_PK_MASK | PFERR_RSVD_MASK));
> > +
> > + /*
> > + * PKRU defines 32 bits, there are 16 domains and 2
> > + * attribute bits per domain in pkru, pkey is the
> > + * index to a defined domain, so the value of
> > + * pkey * 2 is offset of a defined domain.
> > + */
> > + pkru_bits = (kvm_read_pkru(vcpu) >> (pte_pkey * 2)) & 3;
> > + /* replace PFEC.RSVD with ACC_USER_MASK. */
> > + offset = pfec | ((pte_access & PT_USER_MASK) <<
> > + (PFERR_RSVD_BIT - PT_USER_SHIFT));
> > +
> > + pkru_bits &= mmu->pkru_mask >> (offset & ~1);
> > + pfec |= -pkru_bits & PFERR_PK_MASK;
> > + }
> >
> > /*
> > * If CPL < 3, SMAP prevention are disabled if EFLAGS.AC = 1.
> > @@ -167,14 +192,12 @@ static inline u8 permission_fault(struct kvm_vcpu *vcpu, struct kvm_mmu *mmu,
> > * but it will be one in index if SMAP checks are being overridden.
> > * It is important to keep this branchless.
> > */
> > - unsigned long smap = (cpl - 3) & (rflags & X86_EFLAGS_AC);
> > - int index = (pfec >> 1) +
> > - (smap >> (X86_EFLAGS_AC_BIT - PFERR_RSVD_BIT + 1));
> >
> > WARN_ON(pfec & PFERR_RSVD_MASK);
> >
> > pfec |= PFERR_PRESENT_MASK;
> > - return -((mmu->permissions[index] >> pte_access) & 1) & pfec;
> > + return -(((pfec >> PFERR_PK_BIT) |
> > + (mmu->permissions[index] >> pte_access)) & 1) & pfec;
> > }
> >
> > void kvm_mmu_invalidate_zap_all_pages(struct kvm *kvm);
>
> Slightly cleaner:
>
> 1) keep WARN_ON together
> 2) keep smap comment close to smap variable
> 3) build expression for final return a piece at a time
>
> Does it look good?
Accepted.
>
> Thanks,
>
> Paolo
>
> @@ -149,7 +150,8 @@ static inline bool is_write_protection(struct kvm_vcpu *vcpu)
> * if the access faults.
> */
> static inline u8 permission_fault(struct kvm_vcpu *vcpu, struct kvm_mmu *mmu,
> - unsigned pte_access, unsigned pfec)
> + unsigned pte_access, unsigned pte_pkey,
> + unsigned pfec)
> {
> int cpl = kvm_x86_ops->get_cpl(vcpu);
> unsigned long rflags = kvm_x86_ops->get_rflags(vcpu);
> @@ -170,11 +172,32 @@ static inline u8 permission_fault(struct kvm_vcpu *vcpu, struct kvm_mmu *mmu,
> unsigned long smap = (cpl - 3) & (rflags & X86_EFLAGS_AC);
> int index = (pfec >> 1) +
> (smap >> (X86_EFLAGS_AC_BIT - PFERR_RSVD_BIT + 1));
> + bool fault = (mmu->permissions[index] >> pte_access) & 1;
>
> - WARN_ON(pfec & PFERR_RSVD_MASK);
> -
> + WARN_ON(pfec & (PFERR_PK_MASK | PFERR_RSVD_MASK));
> pfec |= PFERR_PRESENT_MASK;
> - return -((mmu->permissions[index] >> pte_access) & 1) & pfec;
> +
> + if (unlikely(mmu->pkru_mask)) {
> + u32 pkru_bits, offset;
> +
> + /*
> + * PKRU defines 32 bits, there are 16 domains and 2
> + * attribute bits per domain in pkru, pkey is the
> + * index to a defined domain, so the value of
> + * pkey * 2 is offset of a defined domain.
> + */
> + pkru_bits = (kvm_read_pkru(vcpu) >> (pte_pkey * 2)) & 3;
> +
> + /* clear present bit, replace PFEC.RSVD with ACC_USER_MASK. */
> + offset = pfec - 1 +
> + ((pte_access & PT_USER_MASK) << (PFERR_RSVD_BIT - PT_USER_SHIFT));
> +
> + pkru_bits &= mmu->pkru_mask >> offset;
> + pfec |= -pkru_bits & PFERR_PK_MASK;
> + fault |= (pkru_bits != 0);
> + }
> +
> + return -(uint32_t)fault & pfec;
> }
>
> void kvm_mmu_invalidate_zap_all_pages(struct kvm *kvm);
> --
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