KVM: x86: Extend KVM_SET_VCPU_EVENTS with selective updates
User space may not want to overwrite asynchronously changing VCPU event
states on write-back. So allow to skip nmi.pending and sipi_vector by
setting corresponding bits in the flags field of kvm_vcpu_events.
[avi: advertise the bits in KVM_GET_VCPU_EVENTS]
Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
diff --git a/Documentation/kvm/api.txt b/Documentation/kvm/api.txt
index e1a1141..2811e45 100644
--- a/Documentation/kvm/api.txt
+++ b/Documentation/kvm/api.txt
@@ -685,7 +685,7 @@
__u8 pad;
} nmi;
__u32 sipi_vector;
- __u32 flags; /* must be zero */
+ __u32 flags;
};
4.30 KVM_SET_VCPU_EVENTS
@@ -701,6 +701,14 @@
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. Keep the
+corresponding bits in the flags field cleared to suppress overwriting the
+current in-kernel state. The bits are:
+
+KVM_VCPUEVENT_VALID_NMI_PENDING - transfer nmi.pending to the kernel
+KVM_VCPUEVENT_VALID_SIPI_VECTOR - transfer sipi_vector
+
5. The kvm_run structure