Commit b577fcb3 authored by Xiao Guangrong's avatar Xiao Guangrong Committed by Luis Henriques

KVM: MMU: fix smap permission check

commit 7cbeed9b 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: default avatarXiao Guangrong <guangrong.xiao@linux.intel.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
Signed-off-by: default avatarLuis Henriques <luis.henriques@canonical.com>
parent aa56fe42
......@@ -174,6 +174,8 @@ 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;
}
......
......@@ -706,6 +706,13 @@ 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);
......
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