On Thu, Mar 27, 2025 at 02:53:24PM +0800, Haoqian He wrote:

2025年3月25日 17:51,Stefano Garzarella <sgarz...@redhat.com> 写道:

On Tue, Mar 25, 2025 at 04:39:46PM +0800, Haoqian He wrote:
2025年3月24日 22:31,Stefano Garzarella <sgarz...@redhat.com> 写道:
On Thu, Mar 20, 2025 at 08:21:30PM +0800, Haoqian He wrote:
2025年3月19日 23:20,Stefano Garzarella <sgarz...@redhat.com> 写道:
On Fri, Mar 14, 2025 at 06:15:34AM -0400, Haoqian He wrote:

[...]

diff --git a/include/hw/virtio/virtio.h b/include/hw/virtio/virtio.h
index 6386910280..c99d56f519 100644
--- a/include/hw/virtio/virtio.h
+++ b/include/hw/virtio/virtio.h
@@ -187,6 +187,7 @@ struct VirtioDeviceClass {
void (*set_config)(VirtIODevice *vdev, const uint8_t *config);
void (*reset)(VirtIODevice *vdev);
void (*set_status)(VirtIODevice *vdev, uint8_t val);
+    int (*set_status_ext)(VirtIODevice *vdev, uint8_t val);

Why we need a new callback instead having `set_status` returning int ?

Because there are other devices such as virtio-net, virtio-ballon, etc.,
we only focus on vhost-user-blk/scsi when live migration.

Why only them?

What I mean, is why in devices where it's not important, don't we just return 0?
It seems more complicated to maintain and confusing for new devices to have 2 
callbacks for the same thing.

Stefano

The series of these patches only want to fix that the inflight IO can't be
completed due to the disconnection between and the vhost-user backend for
vhost-user-blk / scsi devices during live migration. For other virito devices
the issue does not exist, and `vm_state_notify` cannot distinguish specific
devices, it's better not to return error.

Why for example for vhost-user-fs it doesn't exist?


I try to list the virtio sub-devices as follows:

hw/virtio/virtio-iommu.c:    vdc->set_status = virtio_iommu_set_status;
hw/virtio/virtio-balloon.c:    vdc->set_status = virtio_balloon_set_status;
hw/virtio/virtio-rng.c:    vdc->set_status = virtio_rng_set_status;
hw/virtio/virtio-crypto.c:    vdc->set_status = virtio_crypto_set_status;
hw/virtio/vhost-vsock.c:    vdc->set_status = vhost_vsock_set_status;
hw/virtio/vhost-user-vsock.c:    vdc->set_status = vuv_set_status;
hw/virtio/vhost-user-scmi.c:    vdc->set_status = vu_scmi_set_status;
hw/virtio/vhost-user-fs.c:    vdc->set_status = vuf_set_status;
hw/virtio/vhost-user-base.c:    vdc->set_status = vub_set_status;
hw/virtio/vdpa-dev.c:    vdc->set_status = vhost_vdpa_device_set_status;
tests/qtest/libqos/virtio-pci.c:    .set_status = qvirtio_pci_set_status,
tests/qtest/libqos/virtio-pci-modern.c:    .set_status = set_status,
tests/qtest/libqos/virtio-mmio.c:    .set_status = qvirtio_mmio_set_status,
hw/scsi/vhost-user-scsi.c:    vdc->set_status = vhost_user_scsi_set_status;
hw/scsi/vhost-scsi.c:    vdc->set_status = vhost_scsi_set_status;
hw/net/virtio-net.c:    vdc->set_status = virtio_net_set_status;
hw/char/virtio-serial-bus.c:    vdc->set_status = set_status;
hw/block/vhost-user-blk.c:    vdc->set_status = vhost_user_blk_set_status;
hw/block/virtio-blk.c:    vdc->set_status = virtio_blk_set_status;

If the new function pointer type is not added, the number of functions affected
will be very huge. Although it may seem a bit complicated to use two callbacks,
it's much safer.

I can understand that it requires more change, but I don't understand why it's 
safer, can you elaborate?

Anyway let's see what Michael says, if it's okay for him to have 2 callbacks 
for the same thing but differing only by the return value, no objection for me.

Thanks,
Stefano


Hi Stefano, I removed set_status_ext in patch v3, and only changed the return
type of set_status to int. The new changes were applied to all vhost-user
devices, and virtio returned 0 for other devices.

Could you please review patch v3 is reasonable?


There are still questions like those a few lines above that I haven't received answers to, please don't send new versions if we haven't cleared up doubts about the current one first.

I still don't understand why we are only considering vhost-user-blk and vhost-user-scsi, can you elaborate?

Thanks,
Stefano


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