On 2025/04/10 18:32, Philippe Mathieu-Daudé wrote:
Hi Akihiko,
On 10/4/25 09:42, Akihiko Odaki wrote:
virtio-net expects set_features() will be called when the feature set
used by the guest changes to update the number of virtqueues. Call it
during reset as reset clears all features and the queues added for
VIRTIO_NET_F_MQ or VIRTIO_NET_F_RSS will need to be removed.
Fixes: f9d6dbf0bf6e ("virtio-net: remove virtio queues if the guest
doesn't support multiqueue")
Buglink: https://issues.redhat.com/browse/RHEL-73842
Cc: qemu-sta...@nongnu.org
Signed-off-by: Akihiko Odaki <akihiko.od...@daynix.com>
---
hw/virtio/virtio.c | 86 ++++++++++++++++++++++++++
+---------------------------
1 file changed, 43 insertions(+), 43 deletions(-)
diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c
index 85110bce3744..033e87cdd3b9 100644
--- a/hw/virtio/virtio.c
+++ b/hw/virtio/virtio.c
@@ -2316,49 +2316,6 @@ void virtio_queue_enable(VirtIODevice *vdev,
uint32_t queue_index)
}
}
-void virtio_reset(void *opaque)
-{
- VirtIODevice *vdev = opaque;
- VirtioDeviceClass *k = VIRTIO_DEVICE_GET_CLASS(vdev);
- int i;
-
- virtio_set_status(vdev, 0);
- if (current_cpu) {
- /* Guest initiated reset */
- vdev->device_endian = virtio_current_cpu_endian();
- } else {
- /* System reset */
- vdev->device_endian = virtio_default_endian();
- }
-
- if (k->get_vhost) {
- struct vhost_dev *hdev = k->get_vhost(vdev);
- /* Only reset when vhost back-end is connected */
- if (hdev && hdev->vhost_ops) {
- vhost_reset_device(hdev);
- }
- }
-
- if (k->reset) {
- k->reset(vdev);
- }
-
- vdev->start_on_kick = false;
- vdev->started = false;
- vdev->broken = false;
- vdev->guest_features = 0;
- vdev->queue_sel = 0;
- vdev->status = 0;
- vdev->disabled = false;
- qatomic_set(&vdev->isr, 0);
- vdev->config_vector = VIRTIO_NO_VECTOR;
- virtio_notify_vector(vdev, vdev->config_vector);
-
- for(i = 0; i < VIRTIO_QUEUE_MAX; i++) {
- __virtio_queue_reset(vdev, i);
- }
-}
-
void virtio_queue_set_addr(VirtIODevice *vdev, int n, hwaddr addr)
{
if (!vdev->vq[n].vring.num) {
@@ -3169,6 +3126,49 @@ int virtio_set_features(VirtIODevice *vdev,
uint64_t val)
return ret;
}
+void virtio_reset(void *opaque)
+{
+ VirtIODevice *vdev = opaque;
+ VirtioDeviceClass *k = VIRTIO_DEVICE_GET_CLASS(vdev);
+ int i;
+
+ virtio_set_status(vdev, 0);
+ if (current_cpu) {
+ /* Guest initiated reset */
+ vdev->device_endian = virtio_current_cpu_endian();
+ } else {
+ /* System reset */
+ vdev->device_endian = virtio_default_endian();
+ }
+
+ if (k->get_vhost) {
+ struct vhost_dev *hdev = k->get_vhost(vdev);
+ /* Only reset when vhost back-end is connected */
+ if (hdev && hdev->vhost_ops) {
+ vhost_reset_device(hdev);
+ }
+ }
+
+ if (k->reset) {
+ k->reset(vdev);
+ }
+
+ vdev->start_on_kick = false;
+ vdev->started = false;
+ vdev->broken = false;
+ virtio_set_features_nocheck(vdev, 0);
It would be simpler to review having a first patch doing code
movement, then a second one with the addition.
I'm thinking of splitting in the reversed order: add this function call
with a forward declaration in a first patch and move virtio_reset() in a
second one. Hopefully it will also make backporting easier.
For my own education, are feature sets modifiable at runtime?
Looking at the code and spec, yes, I think so. The feature set cannot be
modified if VIRTIO_CONFIG_S_FEATURES_OK is set as part of the "status",
but the flag can be cleared anytime.
+ vdev->queue_sel = 0;
+ vdev->status = 0;
+ vdev->disabled = false;
+ qatomic_set(&vdev->isr, 0);
+ vdev->config_vector = VIRTIO_NO_VECTOR;
+ virtio_notify_vector(vdev, vdev->config_vector);
+
+ for (i = 0; i < VIRTIO_QUEUE_MAX; i++) {
+ __virtio_queue_reset(vdev, i);
+ }
+}
+
static void
virtio_device_check_notification_compatibility(VirtIODevice *vdev,
Error
**errp)
{
---
base-commit: 825b96dbcee23d134b691fc75618b59c5f53da32
change-id: 20250406-reset-5ed5248ee3c1
Best regards,
