Messages in this thread | | | Date | Thu, 07 May 2015 17:50:40 +0800 | From | Xiao Guangrong <> | Subject | Re: [PATCH 1/3] KVM: MMU: fix smap permission check |
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On 05/07/2015 05:32 PM, Paolo Bonzini wrote: > > > 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.
Sure. Actually, i noticed these bugs when i was reviewing your patches, will continue to review soon. :)
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