[PATCH v2 07/12] virtio: queue_reset: pci: support VIRTIO_F_RING_RESET

Michael S. Tsirkin
2022-01-21T10:22:59Z

On Fri, Jan 21, 2022 at 05:22:29AM -0500, Michael S. Tsirkin
wrote:
> On Fri, Jan 21, 2022 at 10:22:59AM +0800, Xuan Zhuo wrote:
> > On Thu, 20 Jan 2022 10:03:45 -0500, Michael S. Tsirkin <mst at
redhat.com> wrote:
> > > On Thu, Jan 20, 2022 at 07:46:20PM +0800, Xuan Zhuo wrote:
> > > > On Thu, 20 Jan 2022 05:55:14 -0500, Michael S. Tsirkin
<mst at redhat.com> wrote:
> > > > > On Thu, Jan 20, 2022 at 02:42:58PM +0800, Xuan Zhuo
wrote:
> > > > > > This patch implements virtio pci support for QUEUE
RESET.
> > > > > >
> > > > > > Performing reset on a queue is divided into two
steps:
> > > > > >
> > > > > > 1. reset_vq: reset one vq
> > > > > > 2. enable_reset_vq: re-enable the reset queue
> > > > > >
> > > > > > In the first step, these tasks will be completed:
> > > > > >    1. notify the hardware queue to reset
> > > > > >    2. recycle the buffer from vq
> > > > > >    3. delete the vq
> > > > > >
> > > > > > When deleting a vq, vp_del_vq() will be called to
release all the memory
> > > > > > of the vq. But this does not affect the process of
deleting vqs, because
> > > > > > that is based on the queue to release all the vqs.
During this process,
> > > > > > the vq has been removed from the queue.
> > > > > >
> > > > > > When deleting vq, info and vq will be released,
and I save msix_vec in
> > > > > > vp_dev->vqs[queue_index]. When re-enable, the
current msix_vec can be
> > > > > > reused. And based on intx_enabled to determine
which method to use to
> > > > > > enable this queue.
> > > > > >
> > > > > > Signed-off-by: Xuan Zhuo <xuanzhuo at
linux.alibaba.com>
> > > > >
> > > > > There's something I don't understand here. It
looks like
> > > > > you assume that when you reset a queue, you also
> > > > > reset the mapping from queue to event vector.
> > > > > The spec does not say it should, and I don't think
it's
> > > > > useful to extend spec to do it - we already have a
simple
> > > > > way to tweak the mapping.
> > > > >
> > > >
> > > > Sorry, what is the already existing method you are referring
to, I didn't find
> > > > it.
> > >
> > >
> > > Write 0xffff into vector number.
> >
> > I wonder if there is some misunderstanding here.
> >
> > My purpose is to release vq, then for the vector used by vq, I hope
that it can
> > be reused when re-enable.
> >
> > But the vector number is not in a fixed order. When I re-enable it, I
don't know
> > what the original vector number is. So I found a place to save this
number.
> >
> > The queue reset I implemented is divided into the following steps:
> > 	1. notify the driver to queue reset
> > 	2. disable_irq()
> > 	3. free unused bufs
> > 	4. free irq, free vq, free info

step 4 here seems pointless.

> > The process of enable is divided into the following steps:
> > 	1. Get the vector number used by the original vq and re-setup vq
> > 	2. enable vq
> > 	3. enable irq
> >
> > If there is anything unreasonable please let me know.
> >
> > Thanks.
>
> Why do you free irq?
>
> > >
> > > > I think you mean that we don't have to reset the event
vector, I think you are
> > > > right.
> > > >
> > > >
> > > >
> > > > Thanks.
> > > >
> > > > > Avoid doing that, and things will be much easier, with
no need
> > > > > to interact with a transport, won't they?
> > > > >
> > > > >
> > > > > > ---
> > > > > >  drivers/virtio/virtio_pci_common.c | 49
++++++++++++++++++++
> > > > > >  drivers/virtio/virtio_pci_common.h |  4 ++
> > > > > >  drivers/virtio/virtio_pci_modern.c | 73
++++++++++++++++++++++++++++++
> > > > > >  3 files changed, 126 insertions(+)
> > > > > >
> > > > > > diff --git a/drivers/virtio/virtio_pci_common.c
b/drivers/virtio/virtio_pci_common.c
> > > > > > index 5afe207ce28a..28b5ffde4621 100644
> > > > > > --- a/drivers/virtio/virtio_pci_common.c
> > > > > > +++ b/drivers/virtio/virtio_pci_common.c
> > > > > > @@ -464,6 +464,55 @@ int vp_find_vqs(struct
virtio_device *vdev, unsigned nvqs,
> > > > > >  	return vp_find_vqs_intx(vdev, nvqs, vqs,
callbacks, names, ctx);
> > > > > >  }
> > > > > >
> > > > > > +#define VQ_IS_DELETED(vp_dev, idx) ((unsigned
long)vp_dev->vqs[idx] & 1)
> > > > > > +#define VQ_RESET_MSIX_VEC(vp_dev, idx) ((unsigned
long)vp_dev->vqs[idx] >> 2)
> > > > > > +#define VQ_RESET_MARK(msix_vec) ((void
*)(long)((msix_vec << 2) + 1))
> > > > > > +
> > > > > > +void vp_del_reset_vq(struct virtio_device *vdev,
u16 queue_index)
> > > > > > +{
> > > > > > +	struct virtio_pci_device *vp_dev =
to_vp_device(vdev);
> > > > > > +	struct virtio_pci_vq_info *info;
> > > > > > +	u16 msix_vec;
> > > > > > +
> > > > > > +	info = vp_dev->vqs[queue_index];
> > > > > > +
> > > > > > +	msix_vec = info->msix_vector;
> > > > > > +
> > > > > > +	/* delete vq */
> > > > > > +	vp_del_vq(info->vq);
> > > > > > +
> > > > > > +	/* Mark the vq has been deleted, and save the
msix_vec. */
> > > > > > +	vp_dev->vqs[queue_index] =
VQ_RESET_MARK(msix_vec);
> > > > > > +}
> > > > > > +
> > > > > > +struct virtqueue *vp_enable_reset_vq(struct
virtio_device *vdev,
> > > > > > +				     int queue_index,
> > > > > > +				     vq_callback_t *callback,
> > > > > > +				     const char *name,
> > > > > > +				     const bool ctx)
> > > > > > +{
> > > > > > +	struct virtio_pci_device *vp_dev =
to_vp_device(vdev);
> > > > > > +	struct virtqueue *vq;
> > > > > > +	u16 msix_vec;
> > > > > > +
> > > > > > +	if (!VQ_IS_DELETED(vp_dev, queue_index))
> > > > > > +		return ERR_PTR(-EPERM);
> > > > > > +
> > > > > > +	msix_vec = VQ_RESET_MSIX_VEC(vp_dev,
queue_index);
> > > > > > +
> > > > > > +	if (vp_dev->intx_enabled)
> > > > > > +		vq = vp_setup_vq(vdev, queue_index, callback,
name, ctx,
> > > > > > +				 VIRTIO_MSI_NO_VECTOR);
> > > > > > +	else
> > > > > > +		vq = vp_enable_vq_msix(vdev, queue_index,
callback, name, ctx,
> > > > > > +				       msix_vec);
> > > > > > +
> > > > > > +	if (IS_ERR(vq))
> > > > > > +		vp_dev->vqs[queue_index] =
VQ_RESET_MARK(msix_vec);
> > > > > > +
> > > > > > +	return vq;
> > > > > > +}
> > > > > > +
> > > > > >  const char *vp_bus_name(struct virtio_device
*vdev)
> > > > > >  {
> > > > > >  	struct virtio_pci_device *vp_dev =
to_vp_device(vdev);
> > > > > > diff --git a/drivers/virtio/virtio_pci_common.h
b/drivers/virtio/virtio_pci_common.h
> > > > > > index 23f6c5c678d5..96c13b1398f8 100644
> > > > > > --- a/drivers/virtio/virtio_pci_common.h
> > > > > > +++ b/drivers/virtio/virtio_pci_common.h
> > > > > > @@ -115,6 +115,10 @@ int vp_find_vqs(struct
virtio_device *vdev, unsigned nvqs,
> > > > > >  		struct virtqueue *vqs[], vq_callback_t
*callbacks[],
> > > > > >  		const char * const names[], const bool *ctx,
> > > > > >  		struct irq_affinity *desc);
> > > > > > +void vp_del_reset_vq(struct virtio_device *vdev,
u16 queue_index);
> > > > > > +struct virtqueue *vp_enable_reset_vq(struct
virtio_device *vdev, int queue_index,
> > > > > > +				     vq_callback_t *callback, const char
*name,
> > > > > > +				     const bool ctx);
> > > > > >  const char *vp_bus_name(struct virtio_device
*vdev);
> > > > > >
> > > > > >  /* Setup the affinity for a virtqueue:
> > > > > > diff --git a/drivers/virtio/virtio_pci_modern.c
b/drivers/virtio/virtio_pci_modern.c
> > > > > > index 5455bc041fb6..fbf87239c920 100644
> > > > > > --- a/drivers/virtio/virtio_pci_modern.c
> > > > > > +++ b/drivers/virtio/virtio_pci_modern.c
> > > > > > @@ -34,6 +34,9 @@ static void
vp_transport_features(struct virtio_device *vdev, u64 features)
> > > > > >  	if ((features & BIT_ULL(VIRTIO_F_SR_IOV))
&&
> > > > > >  			pci_find_ext_capability(pci_dev,
PCI_EXT_CAP_ID_SRIOV))
> > > > > >  		__virtio_set_bit(vdev, VIRTIO_F_SR_IOV);
> > > > > > +
> > > > > > +	if (features & BIT_ULL(VIRTIO_F_RING_RESET))
> > > > > > +		__virtio_set_bit(vdev, VIRTIO_F_RING_RESET);
> > > > > >  }
> > > > > >
> > > > > >  /* virtio config->finalize_features()
implementation */
> > > > > > @@ -176,6 +179,72 @@ static void vp_reset(struct
virtio_device *vdev)
> > > > > >  	vp_disable_cbs(vdev);
> > > > > >  }
> > > > > >
> > > > > > +static int vp_modern_reset_vq(struct
virtio_device *vdev, u16 queue_index,
> > > > > > +			      vq_reset_callback_t *callback, void
*data)
> > > > > > +{
> > > > > > +	struct virtio_pci_device *vp_dev =
to_vp_device(vdev);
> > > > > > +	struct virtio_pci_modern_device *mdev =
&vp_dev->mdev;
> > > > > > +	struct virtio_pci_vq_info *info;
> > > > > > +	u16 msix_vec;
> > > > > > +	void *buf;
> > > > > > +
> > > > > > +	if (!virtio_has_feature(vdev,
VIRTIO_F_RING_RESET))
> > > > > > +		return -ENOENT;
> > > > > > +
> > > > > > +	vp_modern_set_queue_reset(mdev, queue_index);
> > > > > > +
> > > > > > +	/* After write 1 to queue reset, the driver MUST
wait for a read of
> > > > > > +	 * queue reset to return 1.
> > > > > > +	 */
> > > > > > +	while (vp_modern_get_queue_reset(mdev,
queue_index) != 1)
> > > > > > +		msleep(1);
> > > > > > +
> > > > > > +	info = vp_dev->vqs[queue_index];
> > > > > > +	msix_vec = info->msix_vector;
> > > > > > +
> > > > > > +	/* Disable VQ callback. */
> > > > > > +	if (vp_dev->per_vq_vectors &&
msix_vec != VIRTIO_MSI_NO_VECTOR)
> > > > > > +		disable_irq(pci_irq_vector(vp_dev->pci_dev,
msix_vec));
> > > > > > +
> > > > > > +	while ((buf =
virtqueue_detach_unused_buf(info->vq)) != NULL)
> > > > > > +		callback(vdev, buf, data);
> > > > > > +
> > > > > > +	vp_del_reset_vq(vdev, queue_index);
> > > > > > +
> > > > > > +	return 0;
> > > > > > +}
> > > > > > +
> > > > > > +static struct virtqueue
*vp_modern_enable_reset_vq(struct virtio_device *vdev,
> > > > > > +						   u16 queue_index,
> > > > > > +						   vq_callback_t *callback,
> > > > > > +						   const char *name,
> > > > > > +						   const bool *ctx)
> > > > > > +{
> > > > > > +	struct virtio_pci_device *vp_dev =
to_vp_device(vdev);
> > > > > > +	struct virtio_pci_modern_device *mdev =
&vp_dev->mdev;
> > > > > > +	struct virtqueue *vq;
> > > > > > +	u16 msix_vec;
> > > > > > +
> > > > > > +	if (!virtio_has_feature(vdev,
VIRTIO_F_RING_RESET))
> > > > > > +		return ERR_PTR(-ENOENT);
> > > > > > +
> > > > > > +	/* check queue reset status */
> > > > > > +	if (vp_modern_get_queue_reset(mdev, queue_index)
!= 1)
> > > > > > +		return ERR_PTR(-EBUSY);
> > > > > > +
> > > > > > +	vq = vp_enable_reset_vq(vdev, queue_index,
callback, name, ctx);
> > > > > > +	if (IS_ERR(vq))
> > > > > > +		return vq;
> > > > > > +
> > > > > > +	vp_modern_set_queue_enable(&vp_dev->mdev,
vq->index, true);
> > > > > > +
> > > > > > +	msix_vec =
vp_dev->vqs[queue_index]->msix_vector;
> > > > > > +	if (vp_dev->per_vq_vectors &&
msix_vec != VIRTIO_MSI_NO_VECTOR)
> > > > > > +		enable_irq(pci_irq_vector(vp_dev->pci_dev,
msix_vec));
> > > > > > +
> > > > > > +	return vq;
> > > > > > +}
> > > > > > +
> > > > > >  static u16 vp_config_vector(struct
virtio_pci_device *vp_dev, u16 vector)
> > > > > >  {
> > > > > >  	return
vp_modern_config_vector(&vp_dev->mdev, vector);
> > > > > > @@ -395,6 +464,8 @@ static const struct
virtio_config_ops virtio_pci_config_nodev_ops = {
> > > > > >  	.set_vq_affinity = vp_set_vq_affinity,
> > > > > >  	.get_vq_affinity = vp_get_vq_affinity,
> > > > > >  	.get_shm_region  = vp_get_shm_region,
> > > > > > +	.reset_vq	 = vp_modern_reset_vq,
> > > > > > +	.enable_reset_vq = vp_modern_enable_reset_vq,
> > > > > >  };
> > > > > >
> > > > > >  static const struct virtio_config_ops
virtio_pci_config_ops = {
> > > > > > @@ -413,6 +484,8 @@ static const struct
virtio_config_ops virtio_pci_config_ops = {
> > > > > >  	.set_vq_affinity = vp_set_vq_affinity,
> > > > > >  	.get_vq_affinity = vp_get_vq_affinity,
> > > > > >  	.get_shm_region  = vp_get_shm_region,
> > > > > > +	.reset_vq	 = vp_modern_reset_vq,
> > > > > > +	.enable_reset_vq = vp_modern_enable_reset_vq,
> > > > > >  };
> > > > > >
> > > > > >  /* the PCI probing function */
> > > > > > --
> > > > > > 2.31.0
> > > > >
> > >