Commit fce7e152 authored by Vitaly Kuznetsov's avatar Vitaly Kuznetsov Committed by Paolo Bonzini
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KVM: nSVM: Check the value written to MSR_VM_HSAVE_PA 



APM states that #GP is raised upon write to MSR_VM_HSAVE_PA when
the supplied address is not page-aligned or is outside of "maximum
supported physical address for this implementation".
page_address_valid() check seems suitable. Also, forcefully page-align
the address when it's written from VMM.

Signed-off-by: default avatarVitaly Kuznetsov <vkuznets@redhat.com>
Message-Id: <20210628104425.391276-2-vkuznets@redhat.com>
Cc: stable@vger.kernel.org
Reviewed-by: default avatarMaxim Levitsky <mlevitsk@redhat.com>
[Add comment about behavior for host-provided values. - Paolo]
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent c7a1b2b6

arch/x86/kvm/svm/svm.c

+10 −1
Original line number Diff line number Diff line
@@ -2954,7 +2954,16 @@ static int svm_set_msr(struct kvm_vcpu *vcpu, struct msr_data *msr) 
			svm_disable_lbrv(vcpu);

		break;

	case MSR_VM_HSAVE_PA:

		svm->nested.hsave_msr = data;

		/*

		 * Old kernels did not validate the value written to

		 * MSR_VM_HSAVE_PA.  Allow KVM_SET_MSR to set an invalid

		 * value to allow live migrating buggy or malicious guests

		 * originating from those kernels.

		 */

		if (!msr->host_initiated && !page_address_valid(vcpu, data))

			return 1;



		svm->nested.hsave_msr = data & PAGE_MASK;

		break;

	case MSR_VM_CR:

		return svm_set_vm_cr(vcpu, data);