[Qemu-devel] [RFC PATCH v3 3/4] Force eventfd as notifying mechanism for VFIO

[Alvise Rigo]

The method event_notifier_init doesn't assure that eventfd is used.
Create a new method (eventfd_notifier_init) to initialize only eventfd
file descriptors. This method is also used by event_notifier_init which
has not been modified to keep compatibility with util/event_notifier-win32.c.

Signed-off-by: Alvise Rigo <a.r...@virtualopensystems.com>
---
 hw/vfio/pci.c                 | 18 +++++++++---------
 hw/vfio/platform.c            |  8 ++++----
 include/qemu/event_notifier.h |  1 +
 util/event_notifier-posix.c   | 24 +++++++++++++++++++++---
 4 files changed, 35 insertions(+), 16 deletions(-)

diff --git a/hw/vfio/pci.c b/hw/vfio/pci.c
index c86bef9..eae7dce 100644
--- a/hw/vfio/pci.c
+++ b/hw/vfio/pci.c
@@ -261,8 +261,8 @@ static void vfio_enable_intx_kvm(VFIOPCIDevice *vdev)
     pci_irq_deassert(&vdev->pdev);
 
     /* Get an eventfd for resample/unmask */
-    if (event_notifier_init(&vdev->intx.unmask, 0)) {
-        error_report("vfio: Error: event_notifier_init failed eoi");
+    if (eventfd_notifier_init(&vdev->intx.unmask, 0)) {
+        error_report("vfio: Error: eventfd_notifier_init failed eoi");
         goto fail;
     }
 
@@ -414,9 +414,9 @@ static int vfio_enable_intx(VFIOPCIDevice *vdev)
     }
 #endif
 
-    ret = event_notifier_init(&vdev->intx.interrupt, 0);
+    ret = eventfd_notifier_init(&vdev->intx.interrupt, 0);
     if (ret) {
-        error_report("vfio: Error: event_notifier_init failed");
+        error_report("vfio: Error: eventfd_notifier_init failed");
         return ret;
     }
 
@@ -555,8 +555,8 @@ static int vfio_msix_vector_do_use(PCIDevice *pdev, 
unsigned int nr,
 
     msix_vector_use(pdev, nr);
 
-    if (event_notifier_init(&vector->interrupt, 0)) {
-        error_report("vfio: Error: event_notifier_init failed");
+    if (eventfd_notifier_init(&vector->interrupt, 0)) {
+        error_report("vfio: Error: eventfd_notifier_init failed");
     }
 
     /*
@@ -718,8 +718,8 @@ retry:
         vector->vdev = vdev;
         vector->use = true;
 
-        if (event_notifier_init(&vector->interrupt, 0)) {
-            error_report("vfio: Error: event_notifier_init failed");
+        if (eventfd_notifier_init(&vector->interrupt, 0)) {
+            error_report("vfio: Error: eventfd_notifier_init failed");
         }
 
         vector->msg = msi_get_message(&vdev->pdev, i);
@@ -2925,7 +2925,7 @@ static void vfio_register_err_notifier(VFIOPCIDevice 
*vdev)
         return;
     }
 
-    if (event_notifier_init(&vdev->err_notifier, 0)) {
+    if (eventfd_notifier_init(&vdev->err_notifier, 0)) {
         error_report("vfio: Unable to init event notifier for error 
detection");
         vdev->pci_aer = false;
         return;
diff --git a/hw/vfio/platform.c b/hw/vfio/platform.c
index d87fcc3..65dcf0e 100644
--- a/hw/vfio/platform.c
+++ b/hw/vfio/platform.c
@@ -349,9 +349,9 @@ static int vfio_enable_intp(VFIODevice *vdev, unsigned int 
index)
 
     sysbus_init_irq(sbdev, &intp->qemuirq);
 
-    ret = event_notifier_init(&intp->interrupt, 0);
+    ret = eventfd_notifier_init(&intp->interrupt, 0);
     if (ret) {
-        error_report("vfio: Error: event_notifier_init failed ");
+        error_report("vfio: Error: eventfd_notifier_init failed ");
         return ret;
     }
     /* build the irq_set to be passed to the vfio kernel driver */
@@ -471,8 +471,8 @@ static void vfio_enable_intp_kvm(VFIOINTp *intp)
     qemu_set_irq(intp->qemuirq, 0);
 
     /* Get an eventfd for resample/unmask */
-    if (event_notifier_init(&intp->unmask, 0)) {
-        error_report("vfio: Error: event_notifier_init failed eoi");
+    if (eventfd_notifier_init(&intp->unmask, 0)) {
+        error_report("vfio: Error: eventfd_notifier_init failed eoi");
         goto fail;
     }
 
diff --git a/include/qemu/event_notifier.h b/include/qemu/event_notifier.h
index 88b57af..9220069 100644
--- a/include/qemu/event_notifier.h
+++ b/include/qemu/event_notifier.h
@@ -30,6 +30,7 @@ struct EventNotifier {
 
 typedef void EventNotifierHandler(EventNotifier *);
 
+int eventfd_notifier_init(EventNotifier *, int active);
 int event_notifier_init(EventNotifier *, int active);
 void event_notifier_cleanup(EventNotifier *);
 int event_notifier_set(EventNotifier *);
diff --git a/util/event_notifier-posix.c b/util/event_notifier-posix.c
index 8442c6e..bb29760 100644
--- a/util/event_notifier-posix.c
+++ b/util/event_notifier-posix.c
@@ -25,19 +25,37 @@ void event_notifier_init_fd(EventNotifier *e, int fd)
     e->wfd = fd;
 }
 
-int event_notifier_init(EventNotifier *e, int active)
+int eventfd_notifier_init(EventNotifier *e, int active)
 {
-    int fds[2];
     int ret;
 
 #ifdef CONFIG_EVENTFD
     ret = eventfd(0, EFD_NONBLOCK | EFD_CLOEXEC);
+    if (ret >= 0) {
+        e->rfd = e->wfd = ret;
+        ret = 0;
+
+        if (active) {
+            event_notifier_set(e);
+        }
+    }
 #else
     ret = -1;
     errno = ENOSYS;
 #endif
+
+    return ret;
+}
+
+int event_notifier_init(EventNotifier *e, int active)
+{
+    int fds[2];
+    int ret;
+
+    ret = eventfd_notifier_init(e, active);
+
     if (ret >= 0) {
-        e->rfd = e->wfd = ret;
+        return 0;
     } else {
         if (errno != ENOSYS) {
             return -errno;
-- 
1.9.1