KVM: nVMX: Invoke ept_save_pdptrs() if and only if PAE paging is enabled (9932b49e) · Commits · 戴 / test

Invoke ept_save_pdptrs() when restoring L1's host state on a "late" VM-Fail if and only if PAE paging is enabled. This saves a CALL in the common case where L1 is a 64-bit host, and avoids incorrectly marking the PDPTRs as dirty. WARN if ept_save_pdptrs() is called with PAE disabled now that the nested usage pre-checks is_pae_paging(). Barring a bug in KVM's MMU, attempting to read the PDPTRs with PAE disabled is now impossible. Signed-off-by:

Sean Christopherson <sean.j.christopherson@intel.com> Message-Id: <20200415203454.8296-2-sean.j.christopherson@intel.com> Signed-off-by:

Paolo Bonzini <pbonzini@redhat.com>

arch/x86/kvm/vmx/nested.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -4250,7 +4250,7 @@ static void nested_vmx_restore_host_state(struct kvm_vcpu *vcpu)
		* VMFail, like everything else we just need to ensure our
		* software model is up-to-date.
		*/
		if (enable_ept)
		if (enable_ept && is_pae_paging(vcpu))
		ept_save_pdptrs(vcpu);

		kvm_mmu_reset_context(vcpu);

arch/x86/kvm/vmx/vmx.c

+7 −6

Original line number	Diff line number	Diff line
		@@ -2937,12 +2937,13 @@ void ept_save_pdptrs(struct kvm_vcpu *vcpu)
		{
		struct kvm_mmu *mmu = vcpu->arch.walk_mmu;

		if (is_pae_paging(vcpu)) {
		if (WARN_ON_ONCE(!is_pae_paging(vcpu)))
		return;

		mmu->pdptrs[0] = vmcs_read64(GUEST_PDPTR0);
		mmu->pdptrs[1] = vmcs_read64(GUEST_PDPTR1);
		mmu->pdptrs[2] = vmcs_read64(GUEST_PDPTR2);
		mmu->pdptrs[3] = vmcs_read64(GUEST_PDPTR3);
		}

		kvm_register_mark_dirty(vcpu, VCPU_EXREG_PDPTR);
		}

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