KVM: Don't require explicit indication of completion of mmio or pio

It is illegal not to return from a pio or mmio request without completing
it, as mmio or pio is an atomic operation.  Therefore, we can simplify
the userspace interface by avoiding the completion indication.

Signed-off-by: Avi Kivity <avi@qumranet.com>

2 files changed, 24 insertions, 25 deletions

diff --git a/drivers/kvm/kvm_main.c b/drivers/kvm/kvm_main.c
index f267dbb52845..c8b8cfa332bb 100644
--- a/drivers/kvm/kvm_main.c
+++ b/drivers/kvm/kvm_main.c
@@ -1237,8 +1237,10 @@ int emulate_instruction(struct kvm_vcpu *vcpu,
         kvm_arch_ops->decache_regs(vcpu);
         kvm_arch_ops->set_rflags(vcpu, emulate_ctxt.eflags);
 
-        if (vcpu->mmio_is_write)
+        if (vcpu->mmio_is_write) {
+                vcpu->mmio_needed = 0;
                 return EMULATE_DO_MMIO;
+        }
 
         return EMULATE_DONE;
 }
@@ -1692,8 +1694,6 @@ static int complete_pio(struct kvm_vcpu *vcpu)
                         vcpu->regs[VCPU_REGS_RSI] += delta;
         }
 
-        vcpu->run->io_completed = 0;
-
         kvm_arch_ops->decache_regs(vcpu);
 
         io->count -= io->cur_count;
@@ -1800,25 +1800,25 @@ static int kvm_vcpu_ioctl_run(struct kvm_vcpu *vcpu, struct kvm_run *kvm_run)
         /* re-sync apic's tpr */
         vcpu->cr8 = kvm_run->cr8;
 
-        if (kvm_run->io_completed) {
-                if (vcpu->pio.cur_count) {
-                        r = complete_pio(vcpu);
-                        if (r)
-                                goto out;
-                } else if (!vcpu->mmio_is_write) {
-                        memcpy(vcpu->mmio_data, kvm_run->mmio.data, 8);
-                        vcpu->mmio_read_completed = 1;
-                        vcpu->mmio_needed = 0;
-                        r = emulate_instruction(vcpu, kvm_run,
-                                            vcpu->mmio_fault_cr2, 0);
-                        if (r == EMULATE_DO_MMIO) {
-                                /*
-                                 * Read-modify-write.  Back to userspace.
-                                 */
-                                kvm_run->exit_reason = KVM_EXIT_MMIO;
-                                r = 0;
-                                goto out;
-                        }
+        if (vcpu->pio.cur_count) {
+                r = complete_pio(vcpu);
+                if (r)
+                        goto out;
+        }
+
+        if (vcpu->mmio_needed) {
+                memcpy(vcpu->mmio_data, kvm_run->mmio.data, 8);
+                vcpu->mmio_read_completed = 1;
+                vcpu->mmio_needed = 0;
+                r = emulate_instruction(vcpu, kvm_run,
+                                        vcpu->mmio_fault_cr2, 0);
+                if (r == EMULATE_DO_MMIO) {
+                        /*
+                         * Read-modify-write.  Back to userspace.
+                         */
+                        kvm_run->exit_reason = KVM_EXIT_MMIO;
+                        r = 0;
+                        goto out;
                 }
         }
 
diff --git a/include/linux/kvm.h b/include/linux/kvm.h
index 07bf353eeb6f..738c2f50c774 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 10
+#define KVM_API_VERSION 11
 
 /*
  * Architectural interrupt line count, and the size of the bitmap needed
@@ -58,9 +58,8 @@ enum kvm_exit_reason {
 /* for KVM_RUN, returned by mmap(vcpu_fd, offset=0) */
 struct kvm_run {
         /* in */
-        __u32 io_completed; /* mmio/pio request completed */
         __u8 request_interrupt_window;
-        __u8 padding1[3];
+        __u8 padding1[7];
 
         /* out */
         __u32 exit_reason;