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Commit ceee7df7 authored by Xiao Guangrong's avatar Xiao Guangrong Committed by Paolo Bonzini
Browse files

KVM: MMU: fix smap permission check 



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>
parent a4cca3b4

arch/x86/kvm/mmu.h

+2 −0
Original line number Diff line number Diff line
@@ -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;

}

arch/x86/kvm/paging_tmpl.h

+7 −0
Original line number Diff line number Diff line
@@ -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);