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SubjectRe: [PATCH] vhost-net: support VIRTIO_F_RING_RESET
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在 2022/8/25 16:56, Kangjie Xu 写道:
> Add VIRTIO_F_RING_RESET, which indicates that the driver can reset a
> queue individually.
>
> VIRTIO_F_RING_RESET feature is added to virtio-spec 1.2. The relevant
> information is in
> oasis-tcs/virtio-spec#124
> oasis-tcs/virtio-spec#139
>
> The implementation only adds the feature bit in supported features. It
> does not require any other changes because we reuse the existing vhost
> protocol.
>
> The virtqueue reset process can be concluded as two parts:
> 1. The driver can reset a virtqueue. When it is triggered, we use the
> set_backend to disable the virtqueue.
> 2. After the virtqueue is disabled, the driver may optionally re-enable
> it. The process is basically similar to when the device is started,
> except that the restart process does not need to set features and set
> mem table since they do not change. QEMU will send messages containing
> size, base, addr, kickfd and callfd of the virtqueue in order.
> Specifically, the host kernel will receive these messages in order:
> a. VHOST_SET_VRING_NUM
> b. VHOST_SET_VRING_BASE
> c. VHOST_SET_VRING_ADDR
> d. VHOST_SET_VRING_KICK
> e. VHOST_SET_VRING_CALL
> f. VHOST_NET_SET_BACKEND
> Finally, after we use set_backend to attach the virtqueue, the virtqueue
> will be enabled and start to work.
>
> Signed-off-by: Kangjie Xu <kangjie.xu@linux.alibaba.com>
> Signed-off-by: Xuan Zhuo <xuanzhuo@linux.alibaba.com>


Acked-by: Jason Wang <jasowang@redhat.com>


> ---
>
> Test environment and method:
> Host: 5.19.0-rc3
> Qemu: QEMU emulator version 7.0.50 (With vq rset support)
> Guest: 5.19.0-rc3 (With vq reset support)
> Test Cmd: ethtool -g eth1; ethtool -G eth1 rx $1 tx $2; ethtool -g eth1;
>
> The drvier can resize the virtio queue, then virtio queue reset function should
> be triggered.
>
> The default is split mode, modify Qemu virtio-net to add PACKED feature to
> test packed mode.
>
> Guest Kernel Patch:
> https://lore.kernel.org/bpf/20220801063902.129329-1-xuanzhuo@linux.alibaba.com/
>
> QEMU Patch:
> https://lore.kernel.org/qemu-devel/cover.1661414345.git.kangjie.xu@linux.alibaba.com/
>
> Looking forward to your review and comments. Thanks.
>
> drivers/vhost/net.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/vhost/net.c b/drivers/vhost/net.c
> index 68e4ecd1cc0e..8a34928d4fef 100644
> --- a/drivers/vhost/net.c
> +++ b/drivers/vhost/net.c
> @@ -73,7 +73,8 @@ enum {
> VHOST_NET_FEATURES = VHOST_FEATURES |
> (1ULL << VHOST_NET_F_VIRTIO_NET_HDR) |
> (1ULL << VIRTIO_NET_F_MRG_RXBUF) |
> - (1ULL << VIRTIO_F_ACCESS_PLATFORM)
> + (1ULL << VIRTIO_F_ACCESS_PLATFORM) |
> + (1ULL << VIRTIO_F_RING_RESET)
> };
>
> enum {

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