Two nested virtualization fixes for AMD processors.

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Merge tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm

Pull KVM fixes from Paolo Bonzini:
 "Two nested virtualization fixes for AMD processors"

* tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm:
  KVM: nSVM: always intercept VMLOAD/VMSAVE when nested (CVE-2021-3656)
  KVM: nSVM: avoid picking up unsupported bits from L2 in int_ctl (CVE-2021-3653)

arch/x86/include/asm/svm.h

@@ -184,6 +184,8 @@ struct __attribute__ ((__packed__)) vmcb_control_area {
 #define V_IGN_TPR_SHIFT 20
 #define V_IGN_TPR_MASK (1 << V_IGN_TPR_SHIFT)
 
+#define V_IRQ_INJECTION_BITS_MASK (V_IRQ_MASK | V_INTR_PRIO_MASK | V_IGN_TPR_MASK)
+
 #define V_INTR_MASKING_SHIFT 24
 #define V_INTR_MASKING_MASK (1 << V_INTR_MASKING_SHIFT)
 

arch/x86/kvm/svm/nested.c

@@ -158,6 +158,9 @@ void recalc_intercepts(struct vcpu_svm *svm)
 	/* If SMI is not intercepted, ignore guest SMI intercept as well  */
 	if (!intercept_smi)
 		vmcb_clr_intercept(c, INTERCEPT_SMI);
+
+	vmcb_set_intercept(c, INTERCEPT_VMLOAD);
+	vmcb_set_intercept(c, INTERCEPT_VMSAVE);
 }
 
 static void copy_vmcb_control_area(struct vmcb_control_area *dst,
@@ -503,7 +506,11 @@ static void nested_vmcb02_prepare_save(struct vcpu_svm *svm, struct vmcb *vmcb12
 
 static void nested_vmcb02_prepare_control(struct vcpu_svm *svm)
 {
-	const u32 mask = V_INTR_MASKING_MASK | V_GIF_ENABLE_MASK | V_GIF_MASK;
+	const u32 int_ctl_vmcb01_bits =
+		V_INTR_MASKING_MASK | V_GIF_MASK | V_GIF_ENABLE_MASK;
+
+	const u32 int_ctl_vmcb12_bits = V_TPR_MASK | V_IRQ_INJECTION_BITS_MASK;
+
 	struct kvm_vcpu *vcpu = &svm->vcpu;
 
 	/*
@@ -535,8 +542,8 @@ static void nested_vmcb02_prepare_control(struct vcpu_svm *svm)
 		vcpu->arch.l1_tsc_offset + svm->nested.ctl.tsc_offset;
 
 	svm->vmcb->control.int_ctl             =
-		(svm->nested.ctl.int_ctl & ~mask) |
-		(svm->vmcb01.ptr->control.int_ctl & mask);
+		(svm->nested.ctl.int_ctl & int_ctl_vmcb12_bits) |
+		(svm->vmcb01.ptr->control.int_ctl & int_ctl_vmcb01_bits);
 
 	svm->vmcb->control.virt_ext            = svm->nested.ctl.virt_ext;
 	svm->vmcb->control.int_vector          = svm->nested.ctl.int_vector;

arch/x86/kvm/svm/svm.c

@@ -1589,17 +1589,18 @@ static void svm_set_vintr(struct vcpu_svm *svm)
 
 static void svm_clear_vintr(struct vcpu_svm *svm)
 {
-	const u32 mask = V_TPR_MASK | V_GIF_ENABLE_MASK | V_GIF_MASK | V_INTR_MASKING_MASK;
 	svm_clr_intercept(svm, INTERCEPT_VINTR);
 
 	/* Drop int_ctl fields related to VINTR injection.  */
-	svm->vmcb->control.int_ctl &= mask;
+	svm->vmcb->control.int_ctl &= ~V_IRQ_INJECTION_BITS_MASK;
 	if (is_guest_mode(&svm->vcpu)) {
-		svm->vmcb01.ptr->control.int_ctl &= mask;
+		svm->vmcb01.ptr->control.int_ctl &= ~V_IRQ_INJECTION_BITS_MASK;
 
 		WARN_ON((svm->vmcb->control.int_ctl & V_TPR_MASK) !=
 			(svm->nested.ctl.int_ctl & V_TPR_MASK));
-		svm->vmcb->control.int_ctl |= svm->nested.ctl.int_ctl & ~mask;
+
+		svm->vmcb->control.int_ctl |= svm->nested.ctl.int_ctl &
+			V_IRQ_INJECTION_BITS_MASK;
 	}
 
 	vmcb_mark_dirty(svm->vmcb, VMCB_INTR);