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SubjectRe: [PATCH 1/3] KVM: MMU: fix smap permission check


On 07/05/2015 10:20, Xiao Guangrong wrote:
> Current permission check assumes that RSVD bit in PFEC is always zero,
> however, it is not true since MMIO #PF will use it to quickly identify
> MMIO access
>
> Fix it by clearing the bit if walking guest page table is needed
>
> Signed-off-by: Xiao Guangrong <guangrong.xiao@linux.intel.com>
> ---
> arch/x86/kvm/mmu.h | 2 ++
> arch/x86/kvm/paging_tmpl.h | 7 +++++++
> 2 files changed, 9 insertions(+)
>
> diff --git a/arch/x86/kvm/mmu.h b/arch/x86/kvm/mmu.h
> index c7d6563..06eb2fc 100644
> --- a/arch/x86/kvm/mmu.h
> +++ b/arch/x86/kvm/mmu.h
> @@ -166,6 +166,8 @@ static inline bool permission_fault(struct kvm_vcpu *vcpu, struct kvm_mmu *mmu,
> int index = (pfec >> 1) +
> (smap >> (X86_EFLAGS_AC_BIT - PFERR_RSVD_BIT + 1));
>
> + WARN_ON(pfec & PFERR_RSVD_MASK);
> +
> return (mmu->permissions[index] >> pte_access) & 1;
> }
>
> diff --git a/arch/x86/kvm/paging_tmpl.h b/arch/x86/kvm/paging_tmpl.h
> index fd49c86..6e6d115 100644
> --- a/arch/x86/kvm/paging_tmpl.h
> +++ b/arch/x86/kvm/paging_tmpl.h
> @@ -718,6 +718,13 @@ static int FNAME(page_fault)(struct kvm_vcpu *vcpu, gva_t addr, u32 error_code,
> mmu_is_nested(vcpu));
> if (likely(r != RET_MMIO_PF_INVALID))
> return r;
> +
> + /*
> + * page fault with PFEC.RSVD = 1 is caused by shadow
> + * page fault, should not be used to walk guest page
> + * table.
> + */
> + error_code &= ~PFERR_RSVD_MASK;
> };
>
> r = mmu_topup_memory_caches(vcpu);
>

Applied.

For the other patches I'm waiting for an answer re. kvm_mmu_pte_write.

Thanks,

Paolo


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