Re: [PATCH 1/3] vhost: Fix wrong handling of virtqueue array index

[Tetsuya Mukawa <mukawa@igel.co.jp>]

Hi Yuanhan,

I appreciate your checking.
I haven't noticed SET_BACKEND is only supported by vhost-cuse. :-(
I will follow your comments, then submit again.

Thanks,
Tetsuya

On 2015/10/27 15:47, Yuanhan Liu wrote:
> On Tue, Oct 27, 2015 at 03:12:53PM +0900, Tetsuya Mukawa wrote:
>> The patch fixes wrong handling of virtqueue array index.
>>
>> GET_VRING_BASE:
>> The vhost backend will receive the message per virtqueue.
>> Also we should call a destroy callback when both RXQ and TXQ receives
>> the message.
>>
>> SET_BACKEND:
>> Because vhost library supports multiple queue, the index may be over 2.
>> Also a vhost frontend(QEMU) may send such a index.
> Note that only vhost-user supports MQ. vhost-cuse does not.
>
>> Signed-off-by: Tetsuya Mukawa <mukawa@igel.co.jp>
>> ---
>>  lib/librte_vhost/vhost_user/virtio-net-user.c | 22 +++++++++++-----------
>>  lib/librte_vhost/virtio-net.c                 |  5 +++--
>>  2 files changed, 14 insertions(+), 13 deletions(-)
>>
>> diff --git a/lib/librte_vhost/vhost_user/virtio-net-user.c b/lib/librte_vhost/vhost_user/virtio-net-user.c
>> index a998ad8..3e8dfea 100644
>> --- a/lib/librte_vhost/vhost_user/virtio-net-user.c
>> +++ b/lib/librte_vhost/vhost_user/virtio-net-user.c
>> @@ -283,12 +283,10 @@ user_get_vring_base(struct vhost_device_ctx ctx,
>>  	struct vhost_vring_state *state)
>>  {
>>  	struct virtio_net *dev = get_device(ctx);
>> +	uint16_t base_idx = state->index / VIRTIO_QNUM;
> So, fixing what my 1st reply said, for Nth queue pair, state->index
> is "N * 2 + is_tx". So, the base should be "state->index / 2 * 2".
>
>>  
>>  	if (dev == NULL)
>>  		return -1;
>> -	/* We have to stop the queue (virtio) if it is running. */
>> -	if (dev->flags & VIRTIO_DEV_RUNNING)
>> -		notify_ops->destroy_device(dev);
>>  
>>  	/* Here we are safe to get the last used index */
>>  	ops->get_vring_base(ctx, state->index, state);
>> @@ -300,15 +298,17 @@ user_get_vring_base(struct vhost_device_ctx ctx,
>>  	 * sent and only sent in vhost_vring_stop.
>>  	 * TODO: cleanup the vring, it isn't usable since here.
>>  	 */
>> -	if (dev->virtqueue[state->index + VIRTIO_RXQ]->kickfd >= 0) {
>> -		close(dev->virtqueue[state->index + VIRTIO_RXQ]->kickfd);
>> -		dev->virtqueue[state->index + VIRTIO_RXQ]->kickfd = -1;
>> -	}
>> -	if (dev->virtqueue[state->index + VIRTIO_TXQ]->kickfd >= 0) {
>> -		close(dev->virtqueue[state->index + VIRTIO_TXQ]->kickfd);
>> -		dev->virtqueue[state->index + VIRTIO_TXQ]->kickfd = -1;
>> +	if (dev->virtqueue[state->index]->kickfd >= 0) {
>> +		close(dev->virtqueue[state->index]->kickfd);
>> +		dev->virtqueue[state->index]->kickfd = -1;
>>  	}
>>  
>> +	/* We have to stop the queue (virtio) if it is running. */
>> +	if ((dev->flags & VIRTIO_DEV_RUNNING) &&
>> +			(dev->virtqueue[base_idx + VIRTIO_RXQ]->kickfd == -1) &&
>> +			(dev->virtqueue[base_idx + VIRTIO_TXQ]->kickfd == -1))
>> +		notify_ops->destroy_device(dev);
> This is a proper fix then. (You just need fix base_idx).
>
>>  	return 0;
>>  }
>>  
>> @@ -321,7 +321,7 @@ user_set_vring_enable(struct vhost_device_ctx ctx,
>>  		      struct vhost_vring_state *state)
>>  {
>>  	struct virtio_net *dev = get_device(ctx);
>> -	uint16_t base_idx = state->index;
>> +	uint16_t base_idx = state->index / VIRTIO_QNUM;
> user_set_vring_enable is sent per queue pair (I'm sure this time), so
> base_idx equals to state->index. No need fix here.
>
>>  	int enable = (int)state->num;
>>  
>>  	RTE_LOG(INFO, VHOST_CONFIG,
>> diff --git a/lib/librte_vhost/virtio-net.c b/lib/librte_vhost/virtio-net.c
>> index 97213c5..ee2e84d 100644
>> --- a/lib/librte_vhost/virtio-net.c
>> +++ b/lib/librte_vhost/virtio-net.c
>> @@ -778,6 +778,7 @@ static int
>>  set_backend(struct vhost_device_ctx ctx, struct vhost_vring_file *file)
>>  {
>>  	struct virtio_net *dev;
>> +	uint32_t base_idx = file->index / VIRTIO_QNUM;
> As stated, vhost-cuse doesn't not support MQ.
>
> 	--yliu
>>  
>>  	dev = get_device(ctx);
>>  	if (dev == NULL)
>> @@ -791,8 +792,8 @@ set_backend(struct vhost_device_ctx ctx, struct vhost_vring_file *file)
>>  	 * we add the device.
>>  	 */
>>  	if (!(dev->flags & VIRTIO_DEV_RUNNING)) {
>> -		if (((int)dev->virtqueue[VIRTIO_TXQ]->backend != VIRTIO_DEV_STOPPED) &&
>> -			((int)dev->virtqueue[VIRTIO_RXQ]->backend != VIRTIO_DEV_STOPPED)) {
>> +		if (((int)dev->virtqueue[base_idx + VIRTIO_RXQ]->backend != VIRTIO_DEV_STOPPED) &&
>> +			((int)dev->virtqueue[base_idx + VIRTIO_TXQ]->backend != VIRTIO_DEV_STOPPED)) {
>>  			return notify_ops->new_device(dev);
>>  		}
>>  	/* Otherwise we remove it. */
>> -- 
>> 2.1.4