Commit c805f5d5 authored by Sean Christopherson's avatar Sean Christopherson Committed by Paolo Bonzini
Browse files

KVM: nVMX: Defer the MMU reload to the normal path on an EPTP switch 



Defer reloading the MMU after a EPTP successful EPTP switch.  The VMFUNC
instruction itself is executed in the previous EPTP context, any side
effects, e.g. updating RIP, should occur in the old context.  Practically
speaking, this bug is benign as VMX doesn't touch the MMU when skipping
an emulated instruction, nor does queuing a single-step #DB.  No other
post-switch side effects exist.

Fixes: 41ab9372 ("KVM: nVMX: Emulate EPTP switching for the L1 hypervisor")
Cc: stable@vger.kernel.org
Signed-off-by: default avatarSean Christopherson <seanjc@google.com>
Message-Id: <20210305011101.3597423-14-seanjc@google.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent 17e368d9

arch/x86/kvm/vmx/nested.c

+2 −7
Original line number Diff line number Diff line
@@ -5481,16 +5481,11 @@ static int nested_vmx_eptp_switching(struct kvm_vcpu *vcpu, 
		if (!nested_vmx_check_eptp(vcpu, new_eptp))

			return 1;



		kvm_mmu_unload(vcpu);

		mmu->ept_ad = accessed_dirty;

		mmu->mmu_role.base.ad_disabled = !accessed_dirty;

		vmcs12->ept_pointer = new_eptp;

		/*

		 * TODO: Check what's the correct approach in case

		 * mmu reload fails. Currently, we just let the next

		 * reload potentially fail

		 */

		kvm_mmu_reload(vcpu);



		kvm_make_request(KVM_REQ_MMU_RELOAD, vcpu);

	}



	return 0;