[Qemu-devel] [PATCH] virtio/vhost: drop unnecessary VHOST_SET_VRING call

2015-08-12 Thread Marcel Apfelbaum 
No need to send VHOST_SET_VRING_CALL to backend
before the negotiation with the guest is finished.

Signed-off-by: Marcel Apfelbaum mar...@redhat.com
---
 hw/virtio/vhost.c | 13 +
 1 file changed, 1 insertion(+), 12 deletions(-)

diff --git a/hw/virtio/vhost.c b/hw/virtio/vhost.c
index 2712c6f..b448542 100644
--- a/hw/virtio/vhost.c
+++ b/hw/virtio/vhost.c
@@ -875,24 +875,13 @@ static void vhost_eventfd_del(MemoryListener *listener,
 static int vhost_virtqueue_init(struct vhost_dev *dev,
 struct vhost_virtqueue *vq, int n)
 {
-struct vhost_vring_file file = {
-.index = n,
-};
 int r = event_notifier_init(vq-masked_notifier, 0);
+
 if (r  0) {
 return r;
 }
 
-file.fd = event_notifier_get_fd(vq-masked_notifier);
-r = dev-vhost_ops-vhost_call(dev, VHOST_SET_VRING_CALL, file);
-if (r) {
-r = -errno;
-goto fail_call;
-}
 return 0;
-fail_call:
-event_notifier_cleanup(vq-masked_notifier);
-return r;
 }
 
 static void vhost_virtqueue_cleanup(struct vhost_virtqueue *vq)
-- 
2.1.0

Re: [Qemu-devel] [PATCH] virtio/vhost: drop unnecessary VHOST_SET_VRING call

2015-08-12 Thread Michael S. Tsirkin 
On Wed, Aug 12, 2015 at 01:19:51PM +0300, Marcel Apfelbaum wrote:
 No need to send VHOST_SET_VRING_CALL to backend
 before the negotiation with the guest is finished.
 
 Signed-off-by: Marcel Apfelbaum mar...@redhat.com

Well - we do need to set it to the masked notifier initially to avoid
losing events.  You can't just drop it - need to move this call
somewhere else.

 ---
  hw/virtio/vhost.c | 13 +
  1 file changed, 1 insertion(+), 12 deletions(-)
 
 diff --git a/hw/virtio/vhost.c b/hw/virtio/vhost.c
 index 2712c6f..b448542 100644
 --- a/hw/virtio/vhost.c
 +++ b/hw/virtio/vhost.c
 @@ -875,24 +875,13 @@ static void vhost_eventfd_del(MemoryListener *listener,
  static int vhost_virtqueue_init(struct vhost_dev *dev,
  struct vhost_virtqueue *vq, int n)
  {
 -struct vhost_vring_file file = {
 -.index = n,
 -};
  int r = event_notifier_init(vq-masked_notifier, 0);
 +
  if (r  0) {
  return r;
  }
  
 -file.fd = event_notifier_get_fd(vq-masked_notifier);
 -r = dev-vhost_ops-vhost_call(dev, VHOST_SET_VRING_CALL, file);
 -if (r) {
 -r = -errno;
 -goto fail_call;
 -}
  return 0;
 -fail_call:
 -event_notifier_cleanup(vq-masked_notifier);
 -return r;
  }
  
  static void vhost_virtqueue_cleanup(struct vhost_virtqueue *vq)
 -- 
 2.1.0

Re: [Qemu-devel] [PATCH] virtio/vhost: drop unnecessary VHOST_SET_VRING call

2015-08-12 Thread Michael S. Tsirkin 
On Wed, Aug 12, 2015 at 02:10:56PM +0300, Marcel Apfelbaum wrote:
 On 08/12/2015 01:34 PM, Michael S. Tsirkin wrote:
 On Wed, Aug 12, 2015 at 01:19:51PM +0300, Marcel Apfelbaum wrote:
 No need to send VHOST_SET_VRING_CALL to backend
 before the negotiation with the guest is finished.
 
 Signed-off-by: Marcel Apfelbaum mar...@redhat.com
 
 Well - we do need to set it to the masked notifier initially to avoid
 losing events.  You can't just drop it - need to move this call
 somewhere else.
 What do we need to set?
 I just dropped the call to VHOST_SET_VRING_CALL.
 
 Thanks,
 Marcel

We use two eventfds: masked and unmasked one.
We switch dynamically dependent on msi mask value.
Code assumes we start out masked, so we need to match that.


 
 ---
   hw/virtio/vhost.c | 13 +
   1 file changed, 1 insertion(+), 12 deletions(-)
 
 diff --git a/hw/virtio/vhost.c b/hw/virtio/vhost.c
 index 2712c6f..b448542 100644
 --- a/hw/virtio/vhost.c
 +++ b/hw/virtio/vhost.c
 @@ -875,24 +875,13 @@ static void vhost_eventfd_del(MemoryListener 
 *listener,
   static int vhost_virtqueue_init(struct vhost_dev *dev,
   struct vhost_virtqueue *vq, int n)
   {
 -struct vhost_vring_file file = {
 -.index = n,
 -};
   int r = event_notifier_init(vq-masked_notifier, 0);
 +
   if (r  0) {
   return r;
   }
 
 -file.fd = event_notifier_get_fd(vq-masked_notifier);
 -r = dev-vhost_ops-vhost_call(dev, VHOST_SET_VRING_CALL, file);
 -if (r) {
 -r = -errno;
 -goto fail_call;
 -}
   return 0;
 -fail_call:
 -event_notifier_cleanup(vq-masked_notifier);
 -return r;
   }
 
   static void vhost_virtqueue_cleanup(struct vhost_virtqueue *vq)
 --
 2.1.0

Re: [Qemu-devel] [PATCH] virtio/vhost: drop unnecessary VHOST_SET_VRING call

2015-08-12 Thread Marcel Apfelbaum 

On 08/12/2015 01:34 PM, Michael S. Tsirkin wrote:

On Wed, Aug 12, 2015 at 01:19:51PM +0300, Marcel Apfelbaum wrote:

No need to send VHOST_SET_VRING_CALL to backend
before the negotiation with the guest is finished.

Signed-off-by: Marcel Apfelbaum mar...@redhat.com


Well - we do need to set it to the masked notifier initially to avoid
losing events.  You can't just drop it - need to move this call
somewhere else.

What do we need to set?
I just dropped the call to VHOST_SET_VRING_CALL.

Thanks,
Marcel




---
  hw/virtio/vhost.c | 13 +
  1 file changed, 1 insertion(+), 12 deletions(-)

diff --git a/hw/virtio/vhost.c b/hw/virtio/vhost.c
index 2712c6f..b448542 100644
--- a/hw/virtio/vhost.c
+++ b/hw/virtio/vhost.c
@@ -875,24 +875,13 @@ static void vhost_eventfd_del(MemoryListener *listener,
  static int vhost_virtqueue_init(struct vhost_dev *dev,
  struct vhost_virtqueue *vq, int n)
  {
-struct vhost_vring_file file = {
-.index = n,
-};
  int r = event_notifier_init(vq-masked_notifier, 0);
+
  if (r  0) {
  return r;
  }

-file.fd = event_notifier_get_fd(vq-masked_notifier);
-r = dev-vhost_ops-vhost_call(dev, VHOST_SET_VRING_CALL, file);
-if (r) {
-r = -errno;
-goto fail_call;
-}
  return 0;
-fail_call:
-event_notifier_cleanup(vq-masked_notifier);
-return r;
  }

  static void vhost_virtqueue_cleanup(struct vhost_virtqueue *vq)
--
2.1.0