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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: Vitaly Kuznetsov <vkuznets@redhat.com>
Message-Id: <20210628104425.391276-2-vkuznets@redhat.com>
Cc: stable@vger.kernel.org
Reviewed-by: Maxim Levitsky <mlevitsk@redhat.com>
[Add comment about behavior for host-provided values. - Paolo]
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Vitaly Kuznetsov 2021-06-28 12:44:20 +02:00 committed by Paolo Bonzini
parent c7a1b2b678
commit fce7e152ff
1 changed files with 10 additions and 1 deletions
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11
arch/x86/kvm/svm/svm.c
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@ -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);