KVM: Use a shared page for kernel/user communication when runing a vcpu
Instead of passing a 'struct kvm_run' back and forth between the kernel and
userspace, allocate a page and allow the user to mmap() it. This reduces
needless copying and makes the interface expandable by providing lots of
free space.
Signed-off-by: Avi Kivity <avi@qumranet.com>
diff --git a/include/linux/kvm.h b/include/linux/kvm.h
index 275354f..d88e750 100644
--- a/include/linux/kvm.h
+++ b/include/linux/kvm.h
@@ -11,7 +11,7 @@
#include <asm/types.h>
#include <linux/ioctl.h>
-#define KVM_API_VERSION 4
+#define KVM_API_VERSION 5
/*
* Architectural interrupt line count, and the size of the bitmap needed
@@ -49,7 +49,7 @@
KVM_EXIT_SHUTDOWN = 8,
};
-/* for KVM_RUN */
+/* for KVM_RUN, returned by mmap(vcpu_fd, offset=0) */
struct kvm_run {
/* in */
__u32 emulated; /* skip current instruction */
@@ -233,7 +233,7 @@
/*
* ioctls for vcpu fds
*/
-#define KVM_RUN _IOWR(KVMIO, 2, struct kvm_run)
+#define KVM_RUN _IO(KVMIO, 16)
#define KVM_GET_REGS _IOR(KVMIO, 3, struct kvm_regs)
#define KVM_SET_REGS _IOW(KVMIO, 4, struct kvm_regs)
#define KVM_GET_SREGS _IOR(KVMIO, 5, struct kvm_sregs)