vhost: Do not actively send a config interrupt

[PATCH] vhost: Do not actively send a config interrupt

Posted by Li Zhaoxin via 5 days, 23 hours ago

From: lizhaoxin <lizhaoxin04@baidu.com>

After the VM is suspended/resumed or live-migrated,
we do not want the guest to output information such as
the capacity of the block device, as this is noticeable to the tenant.
Also, there is no need to immediately send a config notifier
for the virtio device after vhost_dev_start.

Co-developed-by: Gao Shiyuan <gaoshiyuan@baidu.com>
Signed-off-by: Gao Shiyuan <gaoshiyuan@baidu.com>
Signed-off-by: Li Zhaoxin <lizhaoxin04@baidu.com>
---
 hw/virtio/vhost.c | 7 +------
 1 file changed, 1 insertion(+), 6 deletions(-)

diff --git a/hw/virtio/vhost.c b/hw/virtio/vhost.c
index 6557c58d12..1f8a495ef8 100644
--- a/hw/virtio/vhost.c
+++ b/hw/virtio/vhost.c
@@ -1847,15 +1847,10 @@ static void vhost_stop_config_intr(struct vhost_dev *dev)
 
 static void vhost_start_config_intr(struct vhost_dev *dev)
 {
-    int r;
-
     assert(dev->vhost_ops);
     int fd = event_notifier_get_fd(&dev->vdev->config_notifier);
     if (dev->vhost_ops->vhost_set_config_call) {
-        r = dev->vhost_ops->vhost_set_config_call(dev, fd);
-        if (!r) {
-            event_notifier_set(&dev->vdev->config_notifier);
-        }
+        dev->vhost_ops->vhost_set_config_call(dev, fd);
     }
 }
 
-- 
2.34.1

Re: [PATCH] vhost: Do not actively send a config interrupt

Posted by Stefano Garzarella 5 days, 5 hours ago

CCing Cindy since she introduced this code with commit
f9a09ca3ea ("vhost: add support for configure interrupt"), so she can 
help to review this, since I don't really get this change.

On Mon, Sep 22, 2025 at 11:19:32PM +0800, Li Zhaoxin wrote:
>From: lizhaoxin <lizhaoxin04@baidu.com>
>
>After the VM is suspended/resumed or live-migrated,
>we do not want the guest to output information such as
>the capacity of the block device, as this is noticeable to the tenant.
>Also, there is no need to immediately send a config notifier
>for the virtio device after vhost_dev_start.

Can you explain more clearly what your problem is and why this patch 
solves it?

Thanks,
Stefano

>
>Co-developed-by: Gao Shiyuan <gaoshiyuan@baidu.com>
>Signed-off-by: Gao Shiyuan <gaoshiyuan@baidu.com>
>Signed-off-by: Li Zhaoxin <lizhaoxin04@baidu.com>
>---
> hw/virtio/vhost.c | 7 +------
> 1 file changed, 1 insertion(+), 6 deletions(-)
>
>diff --git a/hw/virtio/vhost.c b/hw/virtio/vhost.c
>index 6557c58d12..1f8a495ef8 100644
>--- a/hw/virtio/vhost.c
>+++ b/hw/virtio/vhost.c
>@@ -1847,15 +1847,10 @@ static void vhost_stop_config_intr(struct vhost_dev *dev)
>
> static void vhost_start_config_intr(struct vhost_dev *dev)
> {
>-    int r;
>-
>     assert(dev->vhost_ops);
>     int fd = event_notifier_get_fd(&dev->vdev->config_notifier);
>     if (dev->vhost_ops->vhost_set_config_call) {
>-        r = dev->vhost_ops->vhost_set_config_call(dev, fd);
>-        if (!r) {
>-            event_notifier_set(&dev->vdev->config_notifier);
>-        }
>+        dev->vhost_ops->vhost_set_config_call(dev, fd);
>     }
> }
>
>-- 
>2.34.1
>