在 2021/8/2 下午4:42, Laurent Vivier 写道:
On 02/08/2021 06:50, Jason Wang wrote:
在 2021/7/30 上午3:19, Laurent Vivier 写道:
Add virtio_queue_disable()/virtio_queue_enable() to disable/enable a queue
by setting vring.num to 0 (or num_default).
This is needed to be able to disable a guest driver from the host side
I suspect this won't work correclty for vhost.
With my test it seems to work with vhost too.
So setting 0 will lead -EINVAL to be returned during
VHOST_SET_VRING_NUM. I think qemu will warn the failure in this case.
What's more important, it's not guaranteed to work for the case of
vhost-user or vhost-vDPA.
And I believe we should only do this after the per queue enabling/disabling is
supported
by the spec.
(only MMIO support that AFAIK)
I don't want to modify the spec.
I need something that works without modifying existing (old) drivers.
The idea is to be able to disable the virtio-net kernel driver from QEMU if the
driver is
too old (i.e. it doesn't support STANDBY feature).
Setting vring.num to 0 forces the kernel driver to exit on error in the probe
function.
It's what I want: the device is present but disabled (the driver is not loaded).
Any other suggestion?
I think we should probably disable the device instead of doing it per
virtqueue.
Thanks
Thanks,
Laurent
Thanks
Signed-off-by: Laurent Vivier <lviv...@redhat.com>
---
include/hw/virtio/virtio.h | 2 ++
hw/virtio/virtio.c | 10 ++++++++++
2 files changed, 12 insertions(+)
diff --git a/include/hw/virtio/virtio.h b/include/hw/virtio/virtio.h
index 8bab9cfb7507..6a3f71b4cd88 100644
--- a/include/hw/virtio/virtio.h
+++ b/include/hw/virtio/virtio.h
@@ -251,6 +251,8 @@ void virtio_config_modern_writel(VirtIODevice *vdev,
uint32_t addr, uint32_t data);
void virtio_queue_set_addr(VirtIODevice *vdev, int n, hwaddr addr);
hwaddr virtio_queue_get_addr(VirtIODevice *vdev, int n);
+void virtio_queue_enable(VirtIODevice *vdev, int n);
+void virtio_queue_disable(VirtIODevice *vdev, int n);
void virtio_queue_set_num(VirtIODevice *vdev, int n, int num);
int virtio_queue_get_num(VirtIODevice *vdev, int n);
int virtio_queue_get_max_num(VirtIODevice *vdev, int n);
diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c
index 874377f37a70..fa5228c1a2d6 100644
--- a/hw/virtio/virtio.c
+++ b/hw/virtio/virtio.c
@@ -2244,6 +2244,16 @@ void virtio_queue_set_rings(VirtIODevice *vdev, int n,
hwaddr desc,
virtio_init_region_cache(vdev, n);
}
+void virtio_queue_disable(VirtIODevice *vdev, int n)
+{
+ vdev->vq[n].vring.num = 0;
+}
+
+void virtio_queue_enable(VirtIODevice *vdev, int n)
+{
+ vdev->vq[n].vring.num = vdev->vq[n].vring.num_default;
+}
+
void virtio_queue_set_num(VirtIODevice *vdev, int n, int num)
{
/* Don't allow guest to flip queue between existent and
