[Qemu-devel] [RFC PATCH v2 3/4] kvm: Common device control API functions

[Christoffer Dall <christoffer.dall@linaro.org>]

Introduces two simple functions:
    int kvm_device_ioctl(int fd, int type, ...);
    int kvm_create_device(KVMState *s, uint64_t type, bool test);

These functions wrap the basic ioctl-based interactions with KVM in a
way similar to other KVM ioctl wrappers.

Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org>

---
Changelog[v2]:
 - Added function docs and adjust code formatting
 - Return proper error value from kvm_create_device
---
 include/sysemu/kvm.h |   22 ++++++++++++++++++++++
 kvm-all.c            |   39 +++++++++++++++++++++++++++++++++++++++
 trace-events         |    1 +
 3 files changed, 62 insertions(+)

diff --git a/include/sysemu/kvm.h b/include/sysemu/kvm.h
index fbb2776..7227a81 100644
--- a/include/sysemu/kvm.h
+++ b/include/sysemu/kvm.h
@@ -190,6 +190,28 @@ int kvm_vm_ioctl(KVMState *s, int type, ...);
 
 int kvm_vcpu_ioctl(CPUState *cpu, int type, ...);
 
+/**
+ * kvm_device_ioctl - call an ioctl on a kvm device
+ * @fd: The KVM device file descriptor as returned from KVM_CREATE_DEVICE
+ * @type: The device-ctrl ioctl number
+ *
+ * Returns: -errno on error, nonnegative on success
+ */
+int kvm_device_ioctl(int fd, int type, ...);
+
+/**
+ * kvm_create_device - create a KVM device for the device control API
+ * @KVMState: The KVMState pointer
+ * @type: The KVM device type (see Documentation/virtual/kvm/devices in the
+ *        kernel source)
+ * @test: If true, only test if device can be created, but don't actually
+ *        create the device.
+ *
+ * Returns: -errno on error, nonnegative on success: @test ? 0 : device fd;
+ */
+int kvm_create_device(KVMState *s, uint64_t type, bool test);
+
+
 /* Arch specific hooks */
 
 extern const KVMCapabilityInfo kvm_arch_required_capabilities[];
diff --git a/kvm-all.c b/kvm-all.c
index fe64f3b..0899c9d 100644
--- a/kvm-all.c
+++ b/kvm-all.c
@@ -1770,6 +1770,24 @@ int kvm_vcpu_ioctl(CPUState *cpu, int type, ...)
     return ret;
 }
 
+int kvm_device_ioctl(int fd, int type, ...)
+{
+    int ret;
+    void *arg;
+    va_list ap;
+
+    va_start(ap, type);
+    arg = va_arg(ap, void *);
+    va_end(ap);
+
+    trace_kvm_device_ioctl(fd, type, arg);
+    ret = ioctl(fd, type, arg);
+    if (ret == -1) {
+        ret = -errno;
+    }
+    return ret;
+}
+
 int kvm_has_sync_mmu(void)
 {
     return kvm_check_extension(kvm_state, KVM_CAP_SYNC_MMU);
@@ -2064,3 +2082,24 @@ int kvm_on_sigbus(int code, void *addr)
 {
     return kvm_arch_on_sigbus(code, addr);
 }
+
+int kvm_create_device(KVMState *s, uint64_t type, bool test)
+{
+    int ret;
+    struct kvm_create_device create_dev;
+
+    create_dev.type = type;
+    create_dev.fd = -1;
+    create_dev.flags = test ? KVM_CREATE_DEVICE_TEST : 0;
+
+    if (!kvm_check_extension(s, KVM_CAP_DEVICE_CTRL)) {
+        return -ENOTSUP;
+    }
+
+    ret = kvm_vm_ioctl(s, KVM_CREATE_DEVICE, &create_dev);
+    if (ret) {
+        return ret;
+    }
+
+    return test ? 0 : create_dev.fd;
+}
diff --git a/trace-events b/trace-events
index 3856b5c..5372c6e 100644
--- a/trace-events
+++ b/trace-events
@@ -1163,6 +1163,7 @@ migrate_set_state(int new_state) "new state %d"
 kvm_ioctl(int type, void *arg) "type %d, arg %p"
 kvm_vm_ioctl(int type, void *arg) "type %d, arg %p"
 kvm_vcpu_ioctl(int cpu_index, int type, void *arg) "cpu_index %d, type %d, arg %p"
+kvm_device_ioctl(int fd, int type, void *arg) "dev fd %d, type %d, arg %p"
 kvm_run_exit(int cpu_index, uint32_t reason) "cpu_index %d, reason %d"
 
 # memory.c
-- 
1.7.10.4