KVM: x86: Extend KVM_SET_VCPU_EVENTS with selective updates

Commit Message

Jan Kiszka Dec. 6, 2009, 4:55 p.m. UTC

None

Patch

diff --git a/Documentation/kvm/api.txt b/Documentation/kvm/api.txt
index e1a1141..ee07e3a 100644
--- a/Documentation/kvm/api.txt
+++ b/Documentation/kvm/api.txt
@@ -685,7 +685,7 @@  struct kvm_vcpu_events {
 		__u8 pad;
 	} nmi;
 	__u32 sipi_vector;
-	__u32 flags;   /* must be zero */
+	__u32 flags;
 };
 
 4.30 KVM_SET_VCPU_EVENTS
@@ -701,6 +701,14 @@  vcpu.
 
 See KVM_GET_VCPU_EVENTS for the data structure.
 
+Fields that may be modified asynchronously by running VCPUs can be excluded
+from the update. These fields are nmi.pending and sipi_vector. Set the
+corresponding mask bits in the flags field to suppress overwriting their
+current state:
+
+KVM_VCPUEVENT_MASK_NMI_PENDING - do not update nmi.pending
+KVM_VCPUEVENT_MASK_SIPI_VECTOR - do not update sipi_vector
+
 
 5. The kvm_run structure
 
diff --git a/arch/x86/include/asm/kvm.h b/arch/x86/include/asm/kvm.h
index 950df43..acf8585 100644
--- a/arch/x86/include/asm/kvm.h
+++ b/arch/x86/include/asm/kvm.h
@@ -254,6 +254,10 @@  struct kvm_reinject_control {
 	__u8 reserved[31];
 };
 
+/* When set in flags, skip corresponding fields on KVM_SET_VCPU_EVENTS */
+#define KVM_VCPUEVENT_MASK_NMI_PENDING	0x00000001
+#define KVM_VCPUEVENT_MASK_SIPI_VECTOR	0x00000002
+
 /* for KVM_GET/SET_VCPU_EVENTS */
 struct kvm_vcpu_events {
 	struct {
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index dd15d7a..368843c 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -1953,7 +1953,8 @@  static void kvm_vcpu_ioctl_x86_get_vcpu_events(struct kvm_vcpu *vcpu,
 static int kvm_vcpu_ioctl_x86_set_vcpu_events(struct kvm_vcpu *vcpu,
 					      struct kvm_vcpu_events *events)
 {
-	if (events->flags)
+	if (events->flags &
+	    ~(KVM_VCPUEVENT_MASK_NMI_PENDING | KVM_VCPUEVENT_MASK_SIPI_VECTOR))
 		return -EINVAL;
 
 	vcpu_load(vcpu);
@@ -1970,10 +1971,12 @@  static int kvm_vcpu_ioctl_x86_set_vcpu_events(struct kvm_vcpu *vcpu,
 		kvm_pic_clear_isr_ack(vcpu->kvm);
 
 	vcpu->arch.nmi_injected = events->nmi.injected;
-	vcpu->arch.nmi_pending = events->nmi.pending;
+	if (!(events->flags & KVM_VCPUEVENT_MASK_NMI_PENDING))
+		vcpu->arch.nmi_pending = events->nmi.pending;
 	kvm_x86_ops->set_nmi_mask(vcpu, events->nmi.masked);
 
-	vcpu->arch.sipi_vector = events->sipi_vector;
+	if (!(events->flags & KVM_VCPUEVENT_MASK_SIPI_VECTOR))
+		vcpu->arch.sipi_vector = events->sipi_vector;
 
 	vcpu_put(vcpu);