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Date: Wed, 17 Jun 2015 15:23:12 -0700 From: Kamal Mostafa <kamal@...onical.com> To: linux-kernel@...r.kernel.org, stable@...r.kernel.org, kernel-team@...ts.ubuntu.com Cc: Xiao Guangrong <guangrong.xiao@...ux.intel.com>, Paolo Bonzini <pbonzini@...hat.com>, Kamal Mostafa <kamal@...onical.com> Subject: [PATCH 3.19.y-ckt 087/146] KVM: MMU: fix smap permission check 3.19.8-ckt2 -stable review patch. If anyone has any objections, please let me know. ------------------ From: Xiao Guangrong <guangrong.xiao@...ux.intel.com> commit 7cbeed9bce7580479bb97457dad220cb3594b875 upstream. 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@...ux.intel.com> Signed-off-by: Paolo Bonzini <pbonzini@...hat.com> Signed-off-by: Kamal Mostafa <kamal@...onical.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 bde8ee7..222fb3e 100644 --- a/arch/x86/kvm/mmu.h +++ b/arch/x86/kvm/mmu.h @@ -179,6 +179,8 @@ 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); -- 1.9.1 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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