KVM: nSVM: Check the value written to MSR_VM_HSAVE_PA

stable inclusion
from stable-5.10.52
commit bedc5d091138f5ee79aebad252a95ad37017039b
bugzilla: 175542 https://gitee.com/openeuler/kernel/issues/I4DTKU

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=bedc5d091138f5ee79aebad252a95ad37017039b

--------------------------------

commit fce7e152 upstream.

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: NVitaly Kuznetsov <vkuznets@redhat.com>
Message-Id: <20210628104425.391276-2-vkuznets@redhat.com>
Cc: stable@vger.kernel.org
Reviewed-by: NMaxim Levitsky <mlevitsk@redhat.com>
[Add comment about behavior for host-provided values. - Paolo]
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: NChen Jun <chenjun102@huawei.com>
Acked-by: NWeilong Chen <chenweilong@huawei.com>
Signed-off-by: NChen Jun <chenjun102@huawei.com>
Signed-off-by: NZheng Zengkai <zhengzengkai@huawei.com>

arch/x86/kvm/svm/svm.c

@@ -2745,7 +2745,16 @@ 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);