Re: [PATCH v6 06/26] virtio_ring: packed: extrace the logic of creating vring

[Xuan Zhuo <xuanzhuo@linux.alibaba.com>]

On Tue, 8 Mar 2022 15:28:22 +0800, Jason Wang <jasowang@redhat.com> wrote:
>
> 在 2022/3/8 下午3:01, Xuan Zhuo 写道:
> > On Mon, 7 Mar 2022 17:17:51 -0500, "Michael S. Tsirkin" <mst@redhat.com> wrote:
> >> On Thu, Feb 24, 2022 at 04:10:42PM +0800, Xuan Zhuo wrote:
> >>> Separate the logic of packed to create vring queue.
> >>>
> >>> For the convenience of passing parameters, add a structure
> >>> vring_packed.
> >>>
> >>> This feature is required for subsequent virtuqueue reset vring.
> >>>
> >>> Signed-off-by: Xuan Zhuo <xuanzhuo@linux.alibaba.com>
> >> Subject has a typo.
> > I will fix it.
> >
> >> Besides:
> >>
> >>> ---
> >>>   drivers/virtio/virtio_ring.c | 121 ++++++++++++++++++++++++++---------
> >>>   1 file changed, 92 insertions(+), 29 deletions(-)
> >>>
> >>> diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c
> >>> index dc6313b79305..41864c5e665f 100644
> >>> --- a/drivers/virtio/virtio_ring.c
> >>> +++ b/drivers/virtio/virtio_ring.c
> >>> @@ -92,6 +92,18 @@ struct vring_split {
> >>>   	struct vring vring;
> >>>   };
> >>>
> >>> +struct vring_packed {
> >>> +	u32 num;
> >>> +	struct vring_packed_desc *ring;
> >>> +	struct vring_packed_desc_event *driver;
> >>> +	struct vring_packed_desc_event *device;
> >>> +	dma_addr_t ring_dma_addr;
> >>> +	dma_addr_t driver_event_dma_addr;
> >>> +	dma_addr_t device_event_dma_addr;
> >>> +	size_t ring_size_in_bytes;
> >>> +	size_t event_size_in_bytes;
> >>> +};
> >>> +
> >>>   struct vring_virtqueue {
> >>>   	struct virtqueue vq;
> >>>
> >>> @@ -1683,45 +1695,101 @@ static struct vring_desc_extra *vring_alloc_desc_extra(struct vring_virtqueue *v
> >>>   	return desc_extra;
> >>>   }
> >>>
> >>> -static struct virtqueue *vring_create_virtqueue_packed(
> >>> -	unsigned int index,
> >>> -	unsigned int num,
> >>> -	unsigned int vring_align,
> >>> -	struct virtio_device *vdev,
> >>> -	bool weak_barriers,
> >>> -	bool may_reduce_num,
> >>> -	bool context,
> >>> -	bool (*notify)(struct virtqueue *),
> >>> -	void (*callback)(struct virtqueue *),
> >>> -	const char *name)
> >>> +static void vring_free_vring_packed(struct vring_packed *vring,
> >>> +				    struct virtio_device *vdev)
> >>> +{
> >>> +	dma_addr_t ring_dma_addr, driver_event_dma_addr, device_event_dma_addr;
> >>> +	struct vring_packed_desc_event *driver, *device;
> >>> +	size_t ring_size_in_bytes, event_size_in_bytes;
> >>> +	struct vring_packed_desc *ring;
> >>> +
> >>> +	ring                  = vring->ring;
> >>> +	driver                = vring->driver;
> >>> +	device                = vring->device;
> >>> +	ring_dma_addr         = vring->ring_size_in_bytes;
> >>> +	event_size_in_bytes   = vring->event_size_in_bytes;
> >>> +	ring_dma_addr         = vring->ring_dma_addr;
> >>> +	driver_event_dma_addr = vring->driver_event_dma_addr;
> >>> +	device_event_dma_addr = vring->device_event_dma_addr;
> >>> +
> >>> +	if (device)
> >>> +		vring_free_queue(vdev, event_size_in_bytes, device, device_event_dma_addr);
> >>> +
> >>> +	if (driver)
> >>> +		vring_free_queue(vdev, event_size_in_bytes, driver, driver_event_dma_addr);
> >>> +
> >>> +	if (ring)
> >>> +		vring_free_queue(vdev, ring_size_in_bytes, ring, ring_dma_addr);
> >> ring_size_in_bytes is uninitialized here.
> >>
> >> Which begs the question how was this tested patchset generally and
> >> this patch in particular.
> >> Please add note on tested configurations and tests run to the patchset.
> > Sorry, my environment is running in split mode. I did not retest the packed mode
> > before sending patches. Because my dpdk vhost-user is not easy to use, I
> > need to change the kernel of the host.
> >
> > I would like to ask if there are other lightweight environments that can be used
> > to test packed mode.
>
>
> You can use Qemu's dataplane. It has support for packed virtqueue.


I thought about it, I feel that the current Qemu's virtio-net seems to have no
problem if it adds a PACKED feature, so I tried it. I manually added the PACKED
feature to Qemu's virtio-net. After I start the vm, run OK. PACKED also
negotiated successfully. After the test, it is also OK.

I think virtio-net in Qemu just does not open PACKED, but the implementation of
PACKED is in virtio core, so as long as virtio-net opens PACKED, it will be
fine. If there is any problem, I hope someone will approve it.

If my idea is correct, then virtio-net can add a parameter to open PACKED, which
will be very convenient when testing the packed mode of virtio.

Thanks.

>
> Thanks
>
>
> >
> >
> > Thanks.
> >
> >
> >>> +}
> >>> +
> >>> +static int vring_create_vring_packed(struct vring_packed *vring,
> >>> +				    struct virtio_device *vdev,
> >>> +				    u32 num)
> >>>   {
> >>> -	struct vring_virtqueue *vq;
> >>>   	struct vring_packed_desc *ring;
> >>>   	struct vring_packed_desc_event *driver, *device;
> >>>   	dma_addr_t ring_dma_addr, driver_event_dma_addr, device_event_dma_addr;
> >>>   	size_t ring_size_in_bytes, event_size_in_bytes;
> >>>
> >>> +	memset(vring, 0, sizeof(*vring));
> >>> +
> >>>   	ring_size_in_bytes = num * sizeof(struct vring_packed_desc);
> >>>
> >>>   	ring = vring_alloc_queue(vdev, ring_size_in_bytes,
> >>>   				 &ring_dma_addr,
> >>>   				 GFP_KERNEL|__GFP_NOWARN|__GFP_ZERO);
> >>>   	if (!ring)
> >>> -		goto err_ring;
> >>> +		goto err;
> >>> +
> >>> +	vring->num = num;
> >>> +	vring->ring = ring;
> >>> +	vring->ring_size_in_bytes = ring_size_in_bytes;
> >>> +	vring->ring_dma_addr = ring_dma_addr;
> >>>
> >>>   	event_size_in_bytes = sizeof(struct vring_packed_desc_event);
> >>> +	vring->event_size_in_bytes = event_size_in_bytes;
> >>>
> >>>   	driver = vring_alloc_queue(vdev, event_size_in_bytes,
> >>>   				   &driver_event_dma_addr,
> >>>   				   GFP_KERNEL|__GFP_NOWARN|__GFP_ZERO);
> >>>   	if (!driver)
> >>> -		goto err_driver;
> >>> +		goto err;
> >>> +
> >>> +	vring->driver = driver;
> >>> +	vring->driver_event_dma_addr = driver_event_dma_addr;
> >>>
> >>>   	device = vring_alloc_queue(vdev, event_size_in_bytes,
> >>>   				   &device_event_dma_addr,
> >>>   				   GFP_KERNEL|__GFP_NOWARN|__GFP_ZERO);
> >>>   	if (!device)
> >>> -		goto err_device;
> >>> +		goto err;
> >>> +
> >>> +	vring->device = device;
> >>> +	vring->device_event_dma_addr = device_event_dma_addr;
> >>> +	return 0;
> >>> +
> >>> +err:
> >>> +	vring_free_vring_packed(vring, vdev);
> >>> +	return -ENOMEM;
> >>> +}
> >>> +
> >>> +static struct virtqueue *vring_create_virtqueue_packed(
> >>> +	unsigned int index,
> >>> +	unsigned int num,
> >>> +	unsigned int vring_align,
> >>> +	struct virtio_device *vdev,
> >>> +	bool weak_barriers,
> >>> +	bool may_reduce_num,
> >>> +	bool context,
> >>> +	bool (*notify)(struct virtqueue *),
> >>> +	void (*callback)(struct virtqueue *),
> >>> +	const char *name)
> >>> +{
> >>> +	struct vring_virtqueue *vq;
> >>> +	struct vring_packed vring;
> >>> +
> >>> +	if (vring_create_vring_packed(&vring, vdev, num))
> >>> +		goto err_vq;
> >>>
> >>>   	vq = kmalloc(sizeof(*vq), GFP_KERNEL);
> >>>   	if (!vq)
> >>> @@ -1753,17 +1821,17 @@ static struct virtqueue *vring_create_virtqueue_packed(
> >>>   	if (virtio_has_feature(vdev, VIRTIO_F_ORDER_PLATFORM))
> >>>   		vq->weak_barriers = false;
> >>>
> >>> -	vq->packed.ring_dma_addr = ring_dma_addr;
> >>> -	vq->packed.driver_event_dma_addr = driver_event_dma_addr;
> >>> -	vq->packed.device_event_dma_addr = device_event_dma_addr;
> >>> +	vq->packed.ring_dma_addr = vring.ring_dma_addr;
> >>> +	vq->packed.driver_event_dma_addr = vring.driver_event_dma_addr;
> >>> +	vq->packed.device_event_dma_addr = vring.device_event_dma_addr;
> >>>
> >>> -	vq->packed.ring_size_in_bytes = ring_size_in_bytes;
> >>> -	vq->packed.event_size_in_bytes = event_size_in_bytes;
> >>> +	vq->packed.ring_size_in_bytes = vring.ring_size_in_bytes;
> >>> +	vq->packed.event_size_in_bytes = vring.event_size_in_bytes;
> >>>
> >>>   	vq->packed.vring.num = num;
> >>> -	vq->packed.vring.desc = ring;
> >>> -	vq->packed.vring.driver = driver;
> >>> -	vq->packed.vring.device = device;
> >>> +	vq->packed.vring.desc = vring.ring;
> >>> +	vq->packed.vring.driver = vring.driver;
> >>> +	vq->packed.vring.device = vring.device;
> >>>
> >>>   	vq->packed.next_avail_idx = 0;
> >>>   	vq->packed.avail_wrap_counter = 1;
> >>> @@ -1804,12 +1872,7 @@ static struct virtqueue *vring_create_virtqueue_packed(
> >>>   err_desc_state:
> >>>   	kfree(vq);
> >>>   err_vq:
> >>> -	vring_free_queue(vdev, event_size_in_bytes, device, device_event_dma_addr);
> >>> -err_device:
> >>> -	vring_free_queue(vdev, event_size_in_bytes, driver, driver_event_dma_addr);
> >>> -err_driver:
> >>> -	vring_free_queue(vdev, ring_size_in_bytes, ring, ring_dma_addr);
> >>> -err_ring:
> >>> +	vring_free_vring_packed(&vring, vdev);
> >>>   	return NULL;
> >>>   }
> >>>
> >>> --
> >>> 2.31.0
>