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Commit 472faffa authored by Sean Christopherson's avatar Sean Christopherson Committed by Radim Krčmář
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KVM: x86: Default to not allowing emulation retry in kvm_mmu_page_fault 



Effectively force kvm_mmu_page_fault() to opt-in to allowing retry to
make it more obvious when and why it allows emulation to be retried.
Previously this approach was less convenient due to retry and
re-execute behavior being controlled by separate flags that were also
inverted in their implementations (opt-in versus opt-out).

Suggested-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
Signed-off-by: default avatarSean Christopherson <sean.j.christopherson@intel.com>
Cc: stable@vger.kernel.org
Signed-off-by: default avatarRadim Krčmář <rkrcmar@redhat.com>
parent 384bf221

arch/x86/kvm/mmu.c

+12 −6
Original line number Original line Diff line number Diff line
@@ -5217,7 +5217,7 @@ static int make_mmu_pages_available(struct kvm_vcpu *vcpu) 
int kvm_mmu_page_fault(struct kvm_vcpu *vcpu, gva_t cr2, u64 error_code,

int kvm_mmu_page_fault(struct kvm_vcpu *vcpu, gva_t cr2, u64 error_code,

		       void *insn, int insn_len)

		       void *insn, int insn_len)

{

{

	int r, emulation_type = EMULTYPE_ALLOW_RETRY;

	int r, emulation_type = 0;

	enum emulation_result er;

	enum emulation_result er;

	bool direct = vcpu->arch.mmu.direct_map;

	bool direct = vcpu->arch.mmu.direct_map;
@@ -5230,11 +5230,9 @@ int kvm_mmu_page_fault(struct kvm_vcpu *vcpu, gva_t cr2, u64 error_code, 
	r = RET_PF_INVALID;

	r = RET_PF_INVALID;

	if (unlikely(error_code & PFERR_RSVD_MASK)) {

	if (unlikely(error_code & PFERR_RSVD_MASK)) {

		r = handle_mmio_page_fault(vcpu, cr2, direct);

		r = handle_mmio_page_fault(vcpu, cr2, direct);

		if (r == RET_PF_EMULATE) {

		if (r == RET_PF_EMULATE)

			emulation_type = 0;

			goto emulate;

			goto emulate;

	}

	}

	}





	if (r == RET_PF_INVALID) {

	if (r == RET_PF_INVALID) {

		r = vcpu->arch.mmu.page_fault(vcpu, cr2, lower_32_bits(error_code),

		r = vcpu->arch.mmu.page_fault(vcpu, cr2, lower_32_bits(error_code),
@@ -5260,8 +5258,16 @@ int kvm_mmu_page_fault(struct kvm_vcpu *vcpu, gva_t cr2, u64 error_code, 
		return 1;

		return 1;

	}

	}





	if (mmio_info_in_cache(vcpu, cr2, direct))

	/*

		emulation_type = 0;

	 * vcpu->arch.mmu.page_fault returned RET_PF_EMULATE, but we can still

	 * optimistically try to just unprotect the page and let the processor

	 * re-execute the instruction that caused the page fault.  Do not allow

	 * retrying MMIO emulation, as it's not only pointless but could also

	 * cause us to enter an infinite loop because the processor will keep

	 * faulting on the non-existent MMIO address.

	 */

	if (!mmio_info_in_cache(vcpu, cr2, direct))

		emulation_type = EMULTYPE_ALLOW_RETRY;

emulate:

emulate:

	/*

	/*

	 * On AMD platforms, under certain conditions insn_len may be zero on #NPF.

	 * On AMD platforms, under certain conditions insn_len may be zero on #NPF.