[PATCH] KVM: API versioning

Add compile-time and run-time API versioning.
Signed-off-by: NAvi Kivity <avi@qumranet.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

drivers/kvm/kvm_main.c

@@ -1603,6 +1603,9 @@ static long kvm_dev_ioctl(struct file *filp,
 	int r = -EINVAL;
 
 	switch (ioctl) {
+	case KVM_GET_API_VERSION:
+		r = KVM_API_VERSION;
+		break;
 	case KVM_CREATE_VCPU: {
 		r = kvm_dev_ioctl_create_vcpu(kvm, arg);
 		if (r)

include/linux/kvm.h

@@ -11,6 +11,8 @@
 #include <asm/types.h>
 #include <linux/ioctl.h>
 
+#define KVM_API_VERSION 1
+
 /*
  * Architectural interrupt line count, and the size of the bitmap needed
  * to hold them.
@@ -209,6 +211,7 @@ struct kvm_dirty_log {
 
 #define KVMIO 0xAE
 
+#define KVM_GET_API_VERSION       _IO(KVMIO, 1)
 #define KVM_RUN                   _IOWR(KVMIO, 2, struct kvm_run)
 #define KVM_GET_REGS              _IOWR(KVMIO, 3, struct kvm_regs)
 #define KVM_SET_REGS              _IOW(KVMIO, 4, struct kvm_regs)