Re: [Qemu-devel] Qemu-devel Digest, Vol 149, Issue 266

2015-08-13 Thread Marcel Apfelbaum 

On 08/13/2015 08:32 AM, Ouyang, Changchun wrote:




-Original Message-
Date: Wed, 12 Aug 2015 14:15:54 +0300
From: Michael S. Tsirkin m...@redhat.com
To: Marcel Apfelbaum mar...@redhat.com
Cc: qemu-devel@nongnu.org
Subject: Re: [Qemu-devel] [PATCH] virtio/vhost: drop unnecessary
VHOST_SET_VRING call
Message-ID: 20150812141448-mutt-send-email-...@redhat.com
Content-Type: text/plain; charset=us-ascii

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.


Agree with m.s.t.
We could not drop it.
Vhost-user multi queue also need this.

I'll try to call it a little bit later instead of dropping it.

Thanks,
Marcel




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] Qemu-devel Digest, Vol 149, Issue 266

2015-08-12 Thread Ouyang, Changchun 


 -Original Message-
 Date: Wed, 12 Aug 2015 14:15:54 +0300
 From: Michael S. Tsirkin m...@redhat.com
 To: Marcel Apfelbaum mar...@redhat.com
 Cc: qemu-devel@nongnu.org
 Subject: Re: [Qemu-devel] [PATCH] virtio/vhost: drop unnecessary
   VHOST_SET_VRING call
 Message-ID: 20150812141448-mutt-send-email-...@redhat.com
 Content-Type: text/plain; charset=us-ascii
 
 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.

Agree with m.s.t.
We could not drop it.
Vhost-user multi queue also need this.

  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