From: Vitaly Kuznetsov Date: Mon, 28 Jun 2021 10:44:20 +0000 (+0200) Subject: KVM: nSVM: Check the value written to MSR_VM_HSAVE_PA X-Git-Tag: microblaze-v5.16~444^2~5 X-Git-Url: http://git.monstr.eu/?a=commitdiff_plain;h=fce7e152ffc8f89d02a80617b16c7aa1527847c8;p=linux-2.6-microblaze.git 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 Message-Id: <20210628104425.391276-2-vkuznets@redhat.com> Cc: stable@vger.kernel.org Reviewed-by: Maxim Levitsky [Add comment about behavior for host-provided values. - Paolo] Signed-off-by: Paolo Bonzini --- diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c index 63488d3beb5b..b6e91de891cb 100644 --- a/arch/x86/kvm/svm/svm.c +++ b/arch/x86/kvm/svm/svm.c @@ -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);