| Message ID | 20220726072225.19884-17-xuanzhuo@linux.alibaba.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | virtio pci support VIRTIO_F_RING_RESET | expand |
在 2022/7/26 15:21, Xuan Zhuo 写道: > virtio ring split supports resize. > > Only after the new vring is successfully allocated based on the new num, > we will release the old vring. In any case, an error is returned, > indicating that the vring still points to the old vring. > > In the case of an error, re-initialize(virtqueue_reinit_split()) the > virtqueue to ensure that the vring can be used. > > Signed-off-by: Xuan Zhuo <xuanzhuo@linux.alibaba.com> > Acked-by: Jason Wang <jasowang@redhat.com> > --- > drivers/virtio/virtio_ring.c | 34 ++++++++++++++++++++++++++++++++++ > 1 file changed, 34 insertions(+) > > diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c > index b6fda91c8059..58355e1ac7d7 100644 > --- a/drivers/virtio/virtio_ring.c > +++ b/drivers/virtio/virtio_ring.c > @@ -220,6 +220,7 @@ static struct virtqueue *__vring_new_virtqueue(unsigned int index, > void (*callback)(struct virtqueue *), > const char *name); > static struct vring_desc_extra *vring_alloc_desc_extra(unsigned int num); > +static void vring_free(struct virtqueue *_vq); > > /* > * Helpers. > @@ -1117,6 +1118,39 @@ static struct virtqueue *vring_create_virtqueue_split( > return vq; > } > > +static int virtqueue_resize_split(struct virtqueue *_vq, u32 num) > +{ > + struct vring_virtqueue_split vring_split = {}; > + struct vring_virtqueue *vq = to_vvq(_vq); > + struct virtio_device *vdev = _vq->vdev; > + int err; > + > + err = vring_alloc_queue_split(&vring_split, vdev, num, > + vq->split.vring_align, > + vq->split.may_reduce_num); > + if (err) > + goto err; I think we don't need to do anything here? > + > + err = vring_alloc_state_extra_split(&vring_split); > + if (err) { > + vring_free_split(&vring_split, vdev); > + goto err; I suggest to move vring_free_split() into a dedicated error label. Thanks > + } > + > + vring_free(&vq->vq); > + > + virtqueue_vring_init_split(&vring_split, vq); > + > + virtqueue_init(vq, vring_split.vring.num); > + virtqueue_vring_attach_split(vq, &vring_split); > + > + return 0; > + > +err: > + virtqueue_reinit_split(vq); > + return -ENOMEM; > +} > + > > /* > * Packed ring specific functions - *_packed().
On Wed, 27 Jul 2022 11:12:19 +0800, Jason Wang <jasowang@redhat.com> wrote: > > 在 2022/7/26 15:21, Xuan Zhuo 写道: > > virtio ring split supports resize. > > > > Only after the new vring is successfully allocated based on the new num, > > we will release the old vring. In any case, an error is returned, > > indicating that the vring still points to the old vring. > > > > In the case of an error, re-initialize(virtqueue_reinit_split()) the > > virtqueue to ensure that the vring can be used. > > > > Signed-off-by: Xuan Zhuo <xuanzhuo@linux.alibaba.com> > > Acked-by: Jason Wang <jasowang@redhat.com> > > --- > > drivers/virtio/virtio_ring.c | 34 ++++++++++++++++++++++++++++++++++ > > 1 file changed, 34 insertions(+) > > > > diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c > > index b6fda91c8059..58355e1ac7d7 100644 > > --- a/drivers/virtio/virtio_ring.c > > +++ b/drivers/virtio/virtio_ring.c > > @@ -220,6 +220,7 @@ static struct virtqueue *__vring_new_virtqueue(unsigned int index, > > void (*callback)(struct virtqueue *), > > const char *name); > > static struct vring_desc_extra *vring_alloc_desc_extra(unsigned int num); > > +static void vring_free(struct virtqueue *_vq); > > > > /* > > * Helpers. > > @@ -1117,6 +1118,39 @@ static struct virtqueue *vring_create_virtqueue_split( > > return vq; > > } > > > > +static int virtqueue_resize_split(struct virtqueue *_vq, u32 num) > > +{ > > + struct vring_virtqueue_split vring_split = {}; > > + struct vring_virtqueue *vq = to_vvq(_vq); > > + struct virtio_device *vdev = _vq->vdev; > > + int err; > > + > > + err = vring_alloc_queue_split(&vring_split, vdev, num, > > + vq->split.vring_align, > > + vq->split.may_reduce_num); > > + if (err) > > + goto err; > > > I think we don't need to do anything here? Am I missing something? > > > > + > > + err = vring_alloc_state_extra_split(&vring_split); > > + if (err) { > > + vring_free_split(&vring_split, vdev); > > + goto err; > > > I suggest to move vring_free_split() into a dedicated error label. Will change. Thanks. > > Thanks > > > > + } > > + > > + vring_free(&vq->vq); > > + > > + virtqueue_vring_init_split(&vring_split, vq); > > + > > + virtqueue_init(vq, vring_split.vring.num); > > + virtqueue_vring_attach_split(vq, &vring_split); > > + > > + return 0; > > + > > +err: > > + virtqueue_reinit_split(vq); > > + return -ENOMEM; > > +} > > + > > > > /* > > * Packed ring specific functions - *_packed(). >
On Wed, Jul 27, 2022 at 3:44 PM Xuan Zhuo <xuanzhuo@linux.alibaba.com> wrote: > > On Wed, 27 Jul 2022 11:12:19 +0800, Jason Wang <jasowang@redhat.com> wrote: > > > > 在 2022/7/26 15:21, Xuan Zhuo 写道: > > > virtio ring split supports resize. > > > > > > Only after the new vring is successfully allocated based on the new num, > > > we will release the old vring. In any case, an error is returned, > > > indicating that the vring still points to the old vring. > > > > > > In the case of an error, re-initialize(virtqueue_reinit_split()) the > > > virtqueue to ensure that the vring can be used. > > > > > > Signed-off-by: Xuan Zhuo <xuanzhuo@linux.alibaba.com> > > > Acked-by: Jason Wang <jasowang@redhat.com> > > > --- > > > drivers/virtio/virtio_ring.c | 34 ++++++++++++++++++++++++++++++++++ > > > 1 file changed, 34 insertions(+) > > > > > > diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c > > > index b6fda91c8059..58355e1ac7d7 100644 > > > --- a/drivers/virtio/virtio_ring.c > > > +++ b/drivers/virtio/virtio_ring.c > > > @@ -220,6 +220,7 @@ static struct virtqueue *__vring_new_virtqueue(unsigned int index, > > > void (*callback)(struct virtqueue *), > > > const char *name); > > > static struct vring_desc_extra *vring_alloc_desc_extra(unsigned int num); > > > +static void vring_free(struct virtqueue *_vq); > > > > > > /* > > > * Helpers. > > > @@ -1117,6 +1118,39 @@ static struct virtqueue *vring_create_virtqueue_split( > > > return vq; > > > } > > > > > > +static int virtqueue_resize_split(struct virtqueue *_vq, u32 num) > > > +{ > > > + struct vring_virtqueue_split vring_split = {}; > > > + struct vring_virtqueue *vq = to_vvq(_vq); > > > + struct virtio_device *vdev = _vq->vdev; > > > + int err; > > > + > > > + err = vring_alloc_queue_split(&vring_split, vdev, num, > > > + vq->split.vring_align, > > > + vq->split.may_reduce_num); > > > + if (err) > > > + goto err; > > > > > > I think we don't need to do anything here? > > Am I missing something? I meant it looks to me most of the virtqueue_reinit() is unnecessary. We probably only need to reinit avail/used idx there. Thanks > > > > > > > > + > > > + err = vring_alloc_state_extra_split(&vring_split); > > > + if (err) { > > > + vring_free_split(&vring_split, vdev); > > > + goto err; > > > > > > I suggest to move vring_free_split() into a dedicated error label. > > Will change. > > Thanks. > > > > > > Thanks > > > > > > > + } > > > + > > > + vring_free(&vq->vq); > > > + > > > + virtqueue_vring_init_split(&vring_split, vq); > > > + > > > + virtqueue_init(vq, vring_split.vring.num); > > > + virtqueue_vring_attach_split(vq, &vring_split); > > > + > > > + return 0; > > > + > > > +err: > > > + virtqueue_reinit_split(vq); > > > + return -ENOMEM; > > > +} > > > + > > > > > > /* > > > * Packed ring specific functions - *_packed(). > > >
On Thu, 28 Jul 2022 10:38:51 +0800, Jason Wang <jasowang@redhat.com> wrote: > On Wed, Jul 27, 2022 at 3:44 PM Xuan Zhuo <xuanzhuo@linux.alibaba.com> wrote: > > > > On Wed, 27 Jul 2022 11:12:19 +0800, Jason Wang <jasowang@redhat.com> wrote: > > > > > > 在 2022/7/26 15:21, Xuan Zhuo 写道: > > > > virtio ring split supports resize. > > > > > > > > Only after the new vring is successfully allocated based on the new num, > > > > we will release the old vring. In any case, an error is returned, > > > > indicating that the vring still points to the old vring. > > > > > > > > In the case of an error, re-initialize(virtqueue_reinit_split()) the > > > > virtqueue to ensure that the vring can be used. > > > > > > > > Signed-off-by: Xuan Zhuo <xuanzhuo@linux.alibaba.com> > > > > Acked-by: Jason Wang <jasowang@redhat.com> > > > > --- > > > > drivers/virtio/virtio_ring.c | 34 ++++++++++++++++++++++++++++++++++ > > > > 1 file changed, 34 insertions(+) > > > > > > > > diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c > > > > index b6fda91c8059..58355e1ac7d7 100644 > > > > --- a/drivers/virtio/virtio_ring.c > > > > +++ b/drivers/virtio/virtio_ring.c > > > > @@ -220,6 +220,7 @@ static struct virtqueue *__vring_new_virtqueue(unsigned int index, > > > > void (*callback)(struct virtqueue *), > > > > const char *name); > > > > static struct vring_desc_extra *vring_alloc_desc_extra(unsigned int num); > > > > +static void vring_free(struct virtqueue *_vq); > > > > > > > > /* > > > > * Helpers. > > > > @@ -1117,6 +1118,39 @@ static struct virtqueue *vring_create_virtqueue_split( > > > > return vq; > > > > } > > > > > > > > +static int virtqueue_resize_split(struct virtqueue *_vq, u32 num) > > > > +{ > > > > + struct vring_virtqueue_split vring_split = {}; > > > > + struct vring_virtqueue *vq = to_vvq(_vq); > > > > + struct virtio_device *vdev = _vq->vdev; > > > > + int err; > > > > + > > > > + err = vring_alloc_queue_split(&vring_split, vdev, num, > > > > + vq->split.vring_align, > > > > + vq->split.may_reduce_num); > > > > + if (err) > > > > + goto err; > > > > > > > > > I think we don't need to do anything here? > > > > Am I missing something? > > I meant it looks to me most of the virtqueue_reinit() is unnecessary. > We probably only need to reinit avail/used idx there. In this function, we can indeed remove some code. > static void virtqueue_reinit_split(struct vring_virtqueue *vq) > { > int size, i; > > memset(vq->split.vring.desc, 0, vq->split.queue_size_in_bytes); > > size = sizeof(struct vring_desc_state_split) * vq->split.vring.num; > memset(vq->split.desc_state, 0, size); > > size = sizeof(struct vring_desc_extra) * vq->split.vring.num; > memset(vq->split.desc_extra, 0, size); These memsets can be removed, and theoretically it will not cause any exceptions. > > > > for (i = 0; i < vq->split.vring.num - 1; i++) > vq->split.desc_extra[i].next = i + 1; This can also be removed, but we need to record free_head that will been update inside virtqueue_init(). > > virtqueue_init(vq, vq->split.vring.num); There are some operations in this, which can also be skipped, such as setting use_dma_api. But I think calling this function directly will be more convenient for maintenance. > virtqueue_vring_init_split(&vq->split, vq); virtqueue_vring_init_split() is necessary. > } Another method, we can take out all the variables to be reinitialized separately, and repackage them into a new function. I don’t think it’s worth it, because this path will only be reached if the memory allocation fails, which is a rare occurrence. In this case, doing so will increase the cost of maintenance. If you think so also, I will remove the above memset in the next version. Thanks. > > Thanks > > > > > > > > > > > > > + > > > > + err = vring_alloc_state_extra_split(&vring_split); > > > > + if (err) { > > > > + vring_free_split(&vring_split, vdev); > > > > + goto err; > > > > > > > > > I suggest to move vring_free_split() into a dedicated error label. > > > > Will change. > > > > Thanks. > > > > > > > > > > Thanks > > > > > > > > > > + } > > > > + > > > > + vring_free(&vq->vq); > > > > + > > > > + virtqueue_vring_init_split(&vring_split, vq); > > > > + > > > > + virtqueue_init(vq, vring_split.vring.num); > > > > + virtqueue_vring_attach_split(vq, &vring_split); > > > > + > > > > + return 0; > > > > + > > > > +err: > > > > + virtqueue_reinit_split(vq); > > > > + return -ENOMEM; > > > > +} > > > > + > > > > > > > > /* > > > > * Packed ring specific functions - *_packed(). > > > > > >
On Thu, Jul 28, 2022 at 3:24 PM Xuan Zhuo <xuanzhuo@linux.alibaba.com> wrote: > > On Thu, 28 Jul 2022 10:38:51 +0800, Jason Wang <jasowang@redhat.com> wrote: > > On Wed, Jul 27, 2022 at 3:44 PM Xuan Zhuo <xuanzhuo@linux.alibaba.com> wrote: > > > > > > On Wed, 27 Jul 2022 11:12:19 +0800, Jason Wang <jasowang@redhat.com> wrote: > > > > > > > > 在 2022/7/26 15:21, Xuan Zhuo 写道: > > > > > virtio ring split supports resize. > > > > > > > > > > Only after the new vring is successfully allocated based on the new num, > > > > > we will release the old vring. In any case, an error is returned, > > > > > indicating that the vring still points to the old vring. > > > > > > > > > > In the case of an error, re-initialize(virtqueue_reinit_split()) the > > > > > virtqueue to ensure that the vring can be used. > > > > > > > > > > Signed-off-by: Xuan Zhuo <xuanzhuo@linux.alibaba.com> > > > > > Acked-by: Jason Wang <jasowang@redhat.com> > > > > > --- > > > > > drivers/virtio/virtio_ring.c | 34 ++++++++++++++++++++++++++++++++++ > > > > > 1 file changed, 34 insertions(+) > > > > > > > > > > diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c > > > > > index b6fda91c8059..58355e1ac7d7 100644 > > > > > --- a/drivers/virtio/virtio_ring.c > > > > > +++ b/drivers/virtio/virtio_ring.c > > > > > @@ -220,6 +220,7 @@ static struct virtqueue *__vring_new_virtqueue(unsigned int index, > > > > > void (*callback)(struct virtqueue *), > > > > > const char *name); > > > > > static struct vring_desc_extra *vring_alloc_desc_extra(unsigned int num); > > > > > +static void vring_free(struct virtqueue *_vq); > > > > > > > > > > /* > > > > > * Helpers. > > > > > @@ -1117,6 +1118,39 @@ static struct virtqueue *vring_create_virtqueue_split( > > > > > return vq; > > > > > } > > > > > > > > > > +static int virtqueue_resize_split(struct virtqueue *_vq, u32 num) > > > > > +{ > > > > > + struct vring_virtqueue_split vring_split = {}; > > > > > + struct vring_virtqueue *vq = to_vvq(_vq); > > > > > + struct virtio_device *vdev = _vq->vdev; > > > > > + int err; > > > > > + > > > > > + err = vring_alloc_queue_split(&vring_split, vdev, num, > > > > > + vq->split.vring_align, > > > > > + vq->split.may_reduce_num); > > > > > + if (err) > > > > > + goto err; > > > > > > > > > > > > I think we don't need to do anything here? > > > > > > Am I missing something? > > > > I meant it looks to me most of the virtqueue_reinit() is unnecessary. > > We probably only need to reinit avail/used idx there. > > > In this function, we can indeed remove some code. > > > static void virtqueue_reinit_split(struct vring_virtqueue *vq) > > { > > int size, i; > > > > memset(vq->split.vring.desc, 0, vq->split.queue_size_in_bytes); > > > > size = sizeof(struct vring_desc_state_split) * vq->split.vring.num; > > memset(vq->split.desc_state, 0, size); > > > > size = sizeof(struct vring_desc_extra) * vq->split.vring.num; > > memset(vq->split.desc_extra, 0, size); > > These memsets can be removed, and theoretically it will not cause any > exceptions. Yes, otherwise we have bugs in detach_buf(). > > > > > > > > > for (i = 0; i < vq->split.vring.num - 1; i++) > > vq->split.desc_extra[i].next = i + 1; > > This can also be removed, but we need to record free_head that will been update > inside virtqueue_init(). We can simply keep free_head unchanged? Otherwise it's a bug somewhere I guess. > > > > > virtqueue_init(vq, vq->split.vring.num); > > There are some operations in this, which can also be skipped, such as setting > use_dma_api. But I think calling this function directly will be more convenient > for maintenance. I don't see anything that is necessary here. > > > > virtqueue_vring_init_split(&vq->split, vq); > > virtqueue_vring_init_split() is necessary. Right. > > > } > > Another method, we can take out all the variables to be reinitialized > separately, and repackage them into a new function. I don’t think it’s worth > it, because this path will only be reached if the memory allocation fails, which > is a rare occurrence. In this case, doing so will increase the cost of > maintenance. If you think so also, I will remove the above memset in the next > version. I agree. Thanks > > Thanks. > > > > > > Thanks > > > > > > > > > > > > > > > > > > + > > > > > + err = vring_alloc_state_extra_split(&vring_split); > > > > > + if (err) { > > > > > + vring_free_split(&vring_split, vdev); > > > > > + goto err; > > > > > > > > > > > > I suggest to move vring_free_split() into a dedicated error label. > > > > > > Will change. > > > > > > Thanks. > > > > > > > > > > > > > > Thanks > > > > > > > > > > > > > + } > > > > > + > > > > > + vring_free(&vq->vq); > > > > > + > > > > > + virtqueue_vring_init_split(&vring_split, vq); > > > > > + > > > > > + virtqueue_init(vq, vring_split.vring.num); > > > > > + virtqueue_vring_attach_split(vq, &vring_split); > > > > > + > > > > > + return 0; > > > > > + > > > > > +err: > > > > > + virtqueue_reinit_split(vq); > > > > > + return -ENOMEM; > > > > > +} > > > > > + > > > > > > > > > > /* > > > > > * Packed ring specific functions - *_packed(). > > > > > > > > > >
On Thu, 28 Jul 2022 15:42:50 +0800, Jason Wang <jasowang@redhat.com> wrote: > On Thu, Jul 28, 2022 at 3:24 PM Xuan Zhuo <xuanzhuo@linux.alibaba.com> wrote: > > > > On Thu, 28 Jul 2022 10:38:51 +0800, Jason Wang <jasowang@redhat.com> wrote: > > > On Wed, Jul 27, 2022 at 3:44 PM Xuan Zhuo <xuanzhuo@linux.alibaba.com> wrote: > > > > > > > > On Wed, 27 Jul 2022 11:12:19 +0800, Jason Wang <jasowang@redhat.com> wrote: > > > > > > > > > > 在 2022/7/26 15:21, Xuan Zhuo 写道: > > > > > > virtio ring split supports resize. > > > > > > > > > > > > Only after the new vring is successfully allocated based on the new num, > > > > > > we will release the old vring. In any case, an error is returned, > > > > > > indicating that the vring still points to the old vring. > > > > > > > > > > > > In the case of an error, re-initialize(virtqueue_reinit_split()) the > > > > > > virtqueue to ensure that the vring can be used. > > > > > > > > > > > > Signed-off-by: Xuan Zhuo <xuanzhuo@linux.alibaba.com> > > > > > > Acked-by: Jason Wang <jasowang@redhat.com> > > > > > > --- > > > > > > drivers/virtio/virtio_ring.c | 34 ++++++++++++++++++++++++++++++++++ > > > > > > 1 file changed, 34 insertions(+) > > > > > > > > > > > > diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c > > > > > > index b6fda91c8059..58355e1ac7d7 100644 > > > > > > --- a/drivers/virtio/virtio_ring.c > > > > > > +++ b/drivers/virtio/virtio_ring.c > > > > > > @@ -220,6 +220,7 @@ static struct virtqueue *__vring_new_virtqueue(unsigned int index, > > > > > > void (*callback)(struct virtqueue *), > > > > > > const char *name); > > > > > > static struct vring_desc_extra *vring_alloc_desc_extra(unsigned int num); > > > > > > +static void vring_free(struct virtqueue *_vq); > > > > > > > > > > > > /* > > > > > > * Helpers. > > > > > > @@ -1117,6 +1118,39 @@ static struct virtqueue *vring_create_virtqueue_split( > > > > > > return vq; > > > > > > } > > > > > > > > > > > > +static int virtqueue_resize_split(struct virtqueue *_vq, u32 num) > > > > > > +{ > > > > > > + struct vring_virtqueue_split vring_split = {}; > > > > > > + struct vring_virtqueue *vq = to_vvq(_vq); > > > > > > + struct virtio_device *vdev = _vq->vdev; > > > > > > + int err; > > > > > > + > > > > > > + err = vring_alloc_queue_split(&vring_split, vdev, num, > > > > > > + vq->split.vring_align, > > > > > > + vq->split.may_reduce_num); > > > > > > + if (err) > > > > > > + goto err; > > > > > > > > > > > > > > > I think we don't need to do anything here? > > > > > > > > Am I missing something? > > > > > > I meant it looks to me most of the virtqueue_reinit() is unnecessary. > > > We probably only need to reinit avail/used idx there. > > > > > > In this function, we can indeed remove some code. > > > > > static void virtqueue_reinit_split(struct vring_virtqueue *vq) > > > { > > > int size, i; > > > > > > memset(vq->split.vring.desc, 0, vq->split.queue_size_in_bytes); > > > > > > size = sizeof(struct vring_desc_state_split) * vq->split.vring.num; > > > memset(vq->split.desc_state, 0, size); > > > > > > size = sizeof(struct vring_desc_extra) * vq->split.vring.num; > > > memset(vq->split.desc_extra, 0, size); > > > > These memsets can be removed, and theoretically it will not cause any > > exceptions. > > Yes, otherwise we have bugs in detach_buf(). > > > > > > > > > > > > > > > for (i = 0; i < vq->split.vring.num - 1; i++) > > > vq->split.desc_extra[i].next = i + 1; > > > > This can also be removed, but we need to record free_head that will been update > > inside virtqueue_init(). > > We can simply keep free_head unchanged? Otherwise it's a bug somewhere I guess. > > > > > > > > > > virtqueue_init(vq, vq->split.vring.num); > > > > There are some operations in this, which can also be skipped, such as setting > > use_dma_api. But I think calling this function directly will be more convenient > > for maintenance. > > I don't see anything that is necessary here. These three are currently inside virtqueue_init() vq->last_used_idx = 0; vq->event_triggered = false; vq->num_added = 0; Thanks. > > > > > > > > virtqueue_vring_init_split(&vq->split, vq); > > > > virtqueue_vring_init_split() is necessary. > > Right. > > > > > > } > > > > Another method, we can take out all the variables to be reinitialized > > separately, and repackage them into a new function. I don’t think it’s worth > > it, because this path will only be reached if the memory allocation fails, which > > is a rare occurrence. In this case, doing so will increase the cost of > > maintenance. If you think so also, I will remove the above memset in the next > > version. > > I agree. > > Thanks > > > > > Thanks. > > > > > > > > > > Thanks > > > > > > > > > > > > > > > > > > > > > > > + > > > > > > + err = vring_alloc_state_extra_split(&vring_split); > > > > > > + if (err) { > > > > > > + vring_free_split(&vring_split, vdev); > > > > > > + goto err; > > > > > > > > > > > > > > > I suggest to move vring_free_split() into a dedicated error label. > > > > > > > > Will change. > > > > > > > > Thanks. > > > > > > > > > > > > > > > > > > Thanks > > > > > > > > > > > > > > > > + } > > > > > > + > > > > > > + vring_free(&vq->vq); > > > > > > + > > > > > > + virtqueue_vring_init_split(&vring_split, vq); > > > > > > + > > > > > > + virtqueue_init(vq, vring_split.vring.num); > > > > > > + virtqueue_vring_attach_split(vq, &vring_split); > > > > > > + > > > > > > + return 0; > > > > > > + > > > > > > +err: > > > > > > + virtqueue_reinit_split(vq); > > > > > > + return -ENOMEM; > > > > > > +} > > > > > > + > > > > > > > > > > > > /* > > > > > > * Packed ring specific functions - *_packed(). > > > > > > > > > > > > > > >
On Thu, Jul 28, 2022 at 4:18 PM Xuan Zhuo <xuanzhuo@linux.alibaba.com> wrote: > > On Thu, 28 Jul 2022 15:42:50 +0800, Jason Wang <jasowang@redhat.com> wrote: > > On Thu, Jul 28, 2022 at 3:24 PM Xuan Zhuo <xuanzhuo@linux.alibaba.com> wrote: > > > > > > On Thu, 28 Jul 2022 10:38:51 +0800, Jason Wang <jasowang@redhat.com> wrote: > > > > On Wed, Jul 27, 2022 at 3:44 PM Xuan Zhuo <xuanzhuo@linux.alibaba.com> wrote: > > > > > > > > > > On Wed, 27 Jul 2022 11:12:19 +0800, Jason Wang <jasowang@redhat.com> wrote: > > > > > > > > > > > > 在 2022/7/26 15:21, Xuan Zhuo 写道: > > > > > > > virtio ring split supports resize. > > > > > > > > > > > > > > Only after the new vring is successfully allocated based on the new num, > > > > > > > we will release the old vring. In any case, an error is returned, > > > > > > > indicating that the vring still points to the old vring. > > > > > > > > > > > > > > In the case of an error, re-initialize(virtqueue_reinit_split()) the > > > > > > > virtqueue to ensure that the vring can be used. > > > > > > > > > > > > > > Signed-off-by: Xuan Zhuo <xuanzhuo@linux.alibaba.com> > > > > > > > Acked-by: Jason Wang <jasowang@redhat.com> > > > > > > > --- > > > > > > > drivers/virtio/virtio_ring.c | 34 ++++++++++++++++++++++++++++++++++ > > > > > > > 1 file changed, 34 insertions(+) > > > > > > > > > > > > > > diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c > > > > > > > index b6fda91c8059..58355e1ac7d7 100644 > > > > > > > --- a/drivers/virtio/virtio_ring.c > > > > > > > +++ b/drivers/virtio/virtio_ring.c > > > > > > > @@ -220,6 +220,7 @@ static struct virtqueue *__vring_new_virtqueue(unsigned int index, > > > > > > > void (*callback)(struct virtqueue *), > > > > > > > const char *name); > > > > > > > static struct vring_desc_extra *vring_alloc_desc_extra(unsigned int num); > > > > > > > +static void vring_free(struct virtqueue *_vq); > > > > > > > > > > > > > > /* > > > > > > > * Helpers. > > > > > > > @@ -1117,6 +1118,39 @@ static struct virtqueue *vring_create_virtqueue_split( > > > > > > > return vq; > > > > > > > } > > > > > > > > > > > > > > +static int virtqueue_resize_split(struct virtqueue *_vq, u32 num) > > > > > > > +{ > > > > > > > + struct vring_virtqueue_split vring_split = {}; > > > > > > > + struct vring_virtqueue *vq = to_vvq(_vq); > > > > > > > + struct virtio_device *vdev = _vq->vdev; > > > > > > > + int err; > > > > > > > + > > > > > > > + err = vring_alloc_queue_split(&vring_split, vdev, num, > > > > > > > + vq->split.vring_align, > > > > > > > + vq->split.may_reduce_num); > > > > > > > + if (err) > > > > > > > + goto err; > > > > > > > > > > > > > > > > > > I think we don't need to do anything here? > > > > > > > > > > Am I missing something? > > > > > > > > I meant it looks to me most of the virtqueue_reinit() is unnecessary. > > > > We probably only need to reinit avail/used idx there. > > > > > > > > > In this function, we can indeed remove some code. > > > > > > > static void virtqueue_reinit_split(struct vring_virtqueue *vq) > > > > { > > > > int size, i; > > > > > > > > memset(vq->split.vring.desc, 0, vq->split.queue_size_in_bytes); > > > > > > > > size = sizeof(struct vring_desc_state_split) * vq->split.vring.num; > > > > memset(vq->split.desc_state, 0, size); > > > > > > > > size = sizeof(struct vring_desc_extra) * vq->split.vring.num; > > > > memset(vq->split.desc_extra, 0, size); > > > > > > These memsets can be removed, and theoretically it will not cause any > > > exceptions. > > > > Yes, otherwise we have bugs in detach_buf(). > > > > > > > > > > > > > > > > > > > > > for (i = 0; i < vq->split.vring.num - 1; i++) > > > > vq->split.desc_extra[i].next = i + 1; > > > > > > This can also be removed, but we need to record free_head that will been update > > > inside virtqueue_init(). > > > > We can simply keep free_head unchanged? Otherwise it's a bug somewhere I guess. > > > > > > > > > > > > > > > virtqueue_init(vq, vq->split.vring.num); > > > > > > There are some operations in this, which can also be skipped, such as setting > > > use_dma_api. But I think calling this function directly will be more convenient > > > for maintenance. > > > > I don't see anything that is necessary here. > > These three are currently inside virtqueue_init() > > vq->last_used_idx = 0; > vq->event_triggered = false; > vq->num_added = 0; Right. Let's keep it there. (Though it's kind of strange that the last_used_idx is not initialized at the same place with avail_idx/flags_shadow, we can optimize it on top). Thanks > > Thanks. > > > > > > > > > > > > > > virtqueue_vring_init_split(&vq->split, vq); > > > > > > virtqueue_vring_init_split() is necessary. > > > > Right. > > > > > > > > > } > > > > > > Another method, we can take out all the variables to be reinitialized > > > separately, and repackage them into a new function. I don’t think it’s worth > > > it, because this path will only be reached if the memory allocation fails, which > > > is a rare occurrence. In this case, doing so will increase the cost of > > > maintenance. If you think so also, I will remove the above memset in the next > > > version. > > > > I agree. > > > > Thanks > > > > > > > > Thanks. > > > > > > > > > > > > > > Thanks > > > > > > > > > > > > > > > > > > > > > > > > > > > > + > > > > > > > + err = vring_alloc_state_extra_split(&vring_split); > > > > > > > + if (err) { > > > > > > > + vring_free_split(&vring_split, vdev); > > > > > > > + goto err; > > > > > > > > > > > > > > > > > > I suggest to move vring_free_split() into a dedicated error label. > > > > > > > > > > Will change. > > > > > > > > > > Thanks. > > > > > > > > > > > > > > > > > > > > > > Thanks > > > > > > > > > > > > > > > > > > > + } > > > > > > > + > > > > > > > + vring_free(&vq->vq); > > > > > > > + > > > > > > > + virtqueue_vring_init_split(&vring_split, vq); > > > > > > > + > > > > > > > + virtqueue_init(vq, vring_split.vring.num); > > > > > > > + virtqueue_vring_attach_split(vq, &vring_split); > > > > > > > + > > > > > > > + return 0; > > > > > > > + > > > > > > > +err: > > > > > > > + virtqueue_reinit_split(vq); > > > > > > > + return -ENOMEM; > > > > > > > +} > > > > > > > + > > > > > > > > > > > > > > /* > > > > > > > * Packed ring specific functions - *_packed(). > > > > > > > > > > > > > > > > > > > > >
On Thu, 28 Jul 2022 17:04:36 +0800, Jason Wang <jasowang@redhat.com> wrote: > On Thu, Jul 28, 2022 at 4:18 PM Xuan Zhuo <xuanzhuo@linux.alibaba.com> wrote: > > > > On Thu, 28 Jul 2022 15:42:50 +0800, Jason Wang <jasowang@redhat.com> wrote: > > > On Thu, Jul 28, 2022 at 3:24 PM Xuan Zhuo <xuanzhuo@linux.alibaba.com> wrote: > > > > > > > > On Thu, 28 Jul 2022 10:38:51 +0800, Jason Wang <jasowang@redhat.com> wrote: > > > > > On Wed, Jul 27, 2022 at 3:44 PM Xuan Zhuo <xuanzhuo@linux.alibaba.com> wrote: > > > > > > > > > > > > On Wed, 27 Jul 2022 11:12:19 +0800, Jason Wang <jasowang@redhat.com> wrote: > > > > > > > > > > > > > > 在 2022/7/26 15:21, Xuan Zhuo 写道: > > > > > > > > virtio ring split supports resize. > > > > > > > > > > > > > > > > Only after the new vring is successfully allocated based on the new num, > > > > > > > > we will release the old vring. In any case, an error is returned, > > > > > > > > indicating that the vring still points to the old vring. > > > > > > > > > > > > > > > > In the case of an error, re-initialize(virtqueue_reinit_split()) the > > > > > > > > virtqueue to ensure that the vring can be used. > > > > > > > > > > > > > > > > Signed-off-by: Xuan Zhuo <xuanzhuo@linux.alibaba.com> > > > > > > > > Acked-by: Jason Wang <jasowang@redhat.com> > > > > > > > > --- > > > > > > > > drivers/virtio/virtio_ring.c | 34 ++++++++++++++++++++++++++++++++++ > > > > > > > > 1 file changed, 34 insertions(+) > > > > > > > > > > > > > > > > diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c > > > > > > > > index b6fda91c8059..58355e1ac7d7 100644 > > > > > > > > --- a/drivers/virtio/virtio_ring.c > > > > > > > > +++ b/drivers/virtio/virtio_ring.c > > > > > > > > @@ -220,6 +220,7 @@ static struct virtqueue *__vring_new_virtqueue(unsigned int index, > > > > > > > > void (*callback)(struct virtqueue *), > > > > > > > > const char *name); > > > > > > > > static struct vring_desc_extra *vring_alloc_desc_extra(unsigned int num); > > > > > > > > +static void vring_free(struct virtqueue *_vq); > > > > > > > > > > > > > > > > /* > > > > > > > > * Helpers. > > > > > > > > @@ -1117,6 +1118,39 @@ static struct virtqueue *vring_create_virtqueue_split( > > > > > > > > return vq; > > > > > > > > } > > > > > > > > > > > > > > > > +static int virtqueue_resize_split(struct virtqueue *_vq, u32 num) > > > > > > > > +{ > > > > > > > > + struct vring_virtqueue_split vring_split = {}; > > > > > > > > + struct vring_virtqueue *vq = to_vvq(_vq); > > > > > > > > + struct virtio_device *vdev = _vq->vdev; > > > > > > > > + int err; > > > > > > > > + > > > > > > > > + err = vring_alloc_queue_split(&vring_split, vdev, num, > > > > > > > > + vq->split.vring_align, > > > > > > > > + vq->split.may_reduce_num); > > > > > > > > + if (err) > > > > > > > > + goto err; > > > > > > > > > > > > > > > > > > > > > I think we don't need to do anything here? > > > > > > > > > > > > Am I missing something? > > > > > > > > > > I meant it looks to me most of the virtqueue_reinit() is unnecessary. > > > > > We probably only need to reinit avail/used idx there. > > > > > > > > > > > > In this function, we can indeed remove some code. > > > > > > > > > static void virtqueue_reinit_split(struct vring_virtqueue *vq) > > > > > { > > > > > int size, i; > > > > > > > > > > memset(vq->split.vring.desc, 0, vq->split.queue_size_in_bytes); > > > > > > > > > > size = sizeof(struct vring_desc_state_split) * vq->split.vring.num; > > > > > memset(vq->split.desc_state, 0, size); > > > > > > > > > > size = sizeof(struct vring_desc_extra) * vq->split.vring.num; > > > > > memset(vq->split.desc_extra, 0, size); > > > > > > > > These memsets can be removed, and theoretically it will not cause any > > > > exceptions. > > > > > > Yes, otherwise we have bugs in detach_buf(). > > > > > > > > > > > > > > > > > > > > > > > > > > > for (i = 0; i < vq->split.vring.num - 1; i++) > > > > > vq->split.desc_extra[i].next = i + 1; > > > > > > > > This can also be removed, but we need to record free_head that will been update > > > > inside virtqueue_init(). > > > > > > We can simply keep free_head unchanged? Otherwise it's a bug somewhere I guess. > > > > > > > > > > > > > > > > > > > > virtqueue_init(vq, vq->split.vring.num); > > > > > > > > There are some operations in this, which can also be skipped, such as setting > > > > use_dma_api. But I think calling this function directly will be more convenient > > > > for maintenance. > > > > > > I don't see anything that is necessary here. > > > > These three are currently inside virtqueue_init() > > > > vq->last_used_idx = 0; > > vq->event_triggered = false; > > vq->num_added = 0; > > Right. Let's keep it there. > > (Though it's kind of strange that the last_used_idx is not initialized > at the same place with avail_idx/flags_shadow, we can optimize it on > top). I put free_head = 0 in the attach function, it is only necessary to set free_head = 0 when a new state/extra is attached. In this way, when we call virtqueue_init(), we don't have to worry about free_head being modified. Rethinking this problem, I think virtqueue_init() can be rewritten and some variables that will not change are removed from it. (use_dma_api, event, weak_barriers) +static void virtqueue_init(struct vring_virtqueue *vq, u32 num) +{ + vq->vq.num_free = num; + + if (vq->packed_ring) + vq->last_used_idx = 0 | (1 << VRING_PACKED_EVENT_F_WRAP_CTR); + else + vq->last_used_idx = 0; + + vq->event_triggered = false; + vq->num_added = 0; + +#ifdef DEBUG + vq->in_use = false; + vq->last_add_time_valid = false; +#endif +} + Thanks. > > Thanks > > > > > Thanks. > > > > > > > > > > > > > > > > > > > > virtqueue_vring_init_split(&vq->split, vq); > > > > > > > > virtqueue_vring_init_split() is necessary. > > > > > > Right. > > > > > > > > > > > > } > > > > > > > > Another method, we can take out all the variables to be reinitialized > > > > separately, and repackage them into a new function. I don’t think it’s worth > > > > it, because this path will only be reached if the memory allocation fails, which > > > > is a rare occurrence. In this case, doing so will increase the cost of > > > > maintenance. If you think so also, I will remove the above memset in the next > > > > version. > > > > > > I agree. > > > > > > Thanks > > > > > > > > > > > Thanks. > > > > > > > > > > > > > > > > > > Thanks > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > + > > > > > > > > + err = vring_alloc_state_extra_split(&vring_split); > > > > > > > > + if (err) { > > > > > > > > + vring_free_split(&vring_split, vdev); > > > > > > > > + goto err; > > > > > > > > > > > > > > > > > > > > > I suggest to move vring_free_split() into a dedicated error label. > > > > > > > > > > > > Will change. > > > > > > > > > > > > Thanks. > > > > > > > > > > > > > > > > > > > > > > > > > > Thanks > > > > > > > > > > > > > > > > > > > > > > + } > > > > > > > > + > > > > > > > > + vring_free(&vq->vq); > > > > > > > > + > > > > > > > > + virtqueue_vring_init_split(&vring_split, vq); > > > > > > > > + > > > > > > > > + virtqueue_init(vq, vring_split.vring.num); > > > > > > > > + virtqueue_vring_attach_split(vq, &vring_split); > > > > > > > > + > > > > > > > > + return 0; > > > > > > > > + > > > > > > > > +err: > > > > > > > > + virtqueue_reinit_split(vq); > > > > > > > > + return -ENOMEM; > > > > > > > > +} > > > > > > > > + > > > > > > > > > > > > > > > > /* > > > > > > > > * Packed ring specific functions - *_packed(). > > > > > > > > > > > > > > > > > > > > > > > > > > > >
On Thu, Jul 28, 2022 at 7:27 PM Xuan Zhuo <xuanzhuo@linux.alibaba.com> wrote: > > On Thu, 28 Jul 2022 17:04:36 +0800, Jason Wang <jasowang@redhat.com> wrote: > > On Thu, Jul 28, 2022 at 4:18 PM Xuan Zhuo <xuanzhuo@linux.alibaba.com> wrote: > > > > > > On Thu, 28 Jul 2022 15:42:50 +0800, Jason Wang <jasowang@redhat.com> wrote: > > > > On Thu, Jul 28, 2022 at 3:24 PM Xuan Zhuo <xuanzhuo@linux.alibaba.com> wrote: > > > > > > > > > > On Thu, 28 Jul 2022 10:38:51 +0800, Jason Wang <jasowang@redhat.com> wrote: > > > > > > On Wed, Jul 27, 2022 at 3:44 PM Xuan Zhuo <xuanzhuo@linux.alibaba.com> wrote: > > > > > > > > > > > > > > On Wed, 27 Jul 2022 11:12:19 +0800, Jason Wang <jasowang@redhat.com> wrote: > > > > > > > > > > > > > > > > 在 2022/7/26 15:21, Xuan Zhuo 写道: > > > > > > > > > virtio ring split supports resize. > > > > > > > > > > > > > > > > > > Only after the new vring is successfully allocated based on the new num, > > > > > > > > > we will release the old vring. In any case, an error is returned, > > > > > > > > > indicating that the vring still points to the old vring. > > > > > > > > > > > > > > > > > > In the case of an error, re-initialize(virtqueue_reinit_split()) the > > > > > > > > > virtqueue to ensure that the vring can be used. > > > > > > > > > > > > > > > > > > Signed-off-by: Xuan Zhuo <xuanzhuo@linux.alibaba.com> > > > > > > > > > Acked-by: Jason Wang <jasowang@redhat.com> > > > > > > > > > --- > > > > > > > > > drivers/virtio/virtio_ring.c | 34 ++++++++++++++++++++++++++++++++++ > > > > > > > > > 1 file changed, 34 insertions(+) > > > > > > > > > > > > > > > > > > diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c > > > > > > > > > index b6fda91c8059..58355e1ac7d7 100644 > > > > > > > > > --- a/drivers/virtio/virtio_ring.c > > > > > > > > > +++ b/drivers/virtio/virtio_ring.c > > > > > > > > > @@ -220,6 +220,7 @@ static struct virtqueue *__vring_new_virtqueue(unsigned int index, > > > > > > > > > void (*callback)(struct virtqueue *), > > > > > > > > > const char *name); > > > > > > > > > static struct vring_desc_extra *vring_alloc_desc_extra(unsigned int num); > > > > > > > > > +static void vring_free(struct virtqueue *_vq); > > > > > > > > > > > > > > > > > > /* > > > > > > > > > * Helpers. > > > > > > > > > @@ -1117,6 +1118,39 @@ static struct virtqueue *vring_create_virtqueue_split( > > > > > > > > > return vq; > > > > > > > > > } > > > > > > > > > > > > > > > > > > +static int virtqueue_resize_split(struct virtqueue *_vq, u32 num) > > > > > > > > > +{ > > > > > > > > > + struct vring_virtqueue_split vring_split = {}; > > > > > > > > > + struct vring_virtqueue *vq = to_vvq(_vq); > > > > > > > > > + struct virtio_device *vdev = _vq->vdev; > > > > > > > > > + int err; > > > > > > > > > + > > > > > > > > > + err = vring_alloc_queue_split(&vring_split, vdev, num, > > > > > > > > > + vq->split.vring_align, > > > > > > > > > + vq->split.may_reduce_num); > > > > > > > > > + if (err) > > > > > > > > > + goto err; > > > > > > > > > > > > > > > > > > > > > > > > I think we don't need to do anything here? > > > > > > > > > > > > > > Am I missing something? > > > > > > > > > > > > I meant it looks to me most of the virtqueue_reinit() is unnecessary. > > > > > > We probably only need to reinit avail/used idx there. > > > > > > > > > > > > > > > In this function, we can indeed remove some code. > > > > > > > > > > > static void virtqueue_reinit_split(struct vring_virtqueue *vq) > > > > > > { > > > > > > int size, i; > > > > > > > > > > > > memset(vq->split.vring.desc, 0, vq->split.queue_size_in_bytes); > > > > > > > > > > > > size = sizeof(struct vring_desc_state_split) * vq->split.vring.num; > > > > > > memset(vq->split.desc_state, 0, size); > > > > > > > > > > > > size = sizeof(struct vring_desc_extra) * vq->split.vring.num; > > > > > > memset(vq->split.desc_extra, 0, size); > > > > > > > > > > These memsets can be removed, and theoretically it will not cause any > > > > > exceptions. > > > > > > > > Yes, otherwise we have bugs in detach_buf(). > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > for (i = 0; i < vq->split.vring.num - 1; i++) > > > > > > vq->split.desc_extra[i].next = i + 1; > > > > > > > > > > This can also be removed, but we need to record free_head that will been update > > > > > inside virtqueue_init(). > > > > > > > > We can simply keep free_head unchanged? Otherwise it's a bug somewhere I guess. > > > > > > > > > > > > > > > > > > > > > > > > > virtqueue_init(vq, vq->split.vring.num); > > > > > > > > > > There are some operations in this, which can also be skipped, such as setting > > > > > use_dma_api. But I think calling this function directly will be more convenient > > > > > for maintenance. > > > > > > > > I don't see anything that is necessary here. > > > > > > These three are currently inside virtqueue_init() > > > > > > vq->last_used_idx = 0; > > > vq->event_triggered = false; > > > vq->num_added = 0; > > > > Right. Let's keep it there. > > > > (Though it's kind of strange that the last_used_idx is not initialized > > at the same place with avail_idx/flags_shadow, we can optimize it on > > top). > > I put free_head = 0 in the attach function, it is only necessary to set > free_head = 0 when a new state/extra is attached. Ok, so I meant I tend to keep it to make this series converge soon :) We can do optimization on top anyhow. Thanks > > In this way, when we call virtqueue_init(), we don't have to worry about > free_head being modified. > > Rethinking this problem, I think virtqueue_init() can be rewritten and some > variables that will not change are removed from it. (use_dma_api, event, > weak_barriers) > > +static void virtqueue_init(struct vring_virtqueue *vq, u32 num) > +{ > + vq->vq.num_free = num; > + > + if (vq->packed_ring) > + vq->last_used_idx = 0 | (1 << VRING_PACKED_EVENT_F_WRAP_CTR); > + else > + vq->last_used_idx = 0; > + > + vq->event_triggered = false; > + vq->num_added = 0; > + > +#ifdef DEBUG > + vq->in_use = false; > + vq->last_add_time_valid = false; > +#endif > +} > + > > Thanks. > > > > > > Thanks > > > > > > > > Thanks. > > > > > > > > > > > > > > > > > > > > > > > > > > virtqueue_vring_init_split(&vq->split, vq); > > > > > > > > > > virtqueue_vring_init_split() is necessary. > > > > > > > > Right. > > > > > > > > > > > > > > > } > > > > > > > > > > Another method, we can take out all the variables to be reinitialized > > > > > separately, and repackage them into a new function. I don’t think it’s worth > > > > > it, because this path will only be reached if the memory allocation fails, which > > > > > is a rare occurrence. In this case, doing so will increase the cost of > > > > > maintenance. If you think so also, I will remove the above memset in the next > > > > > version. > > > > > > > > I agree. > > > > > > > > Thanks > > > > > > > > > > > > > > Thanks. > > > > > > > > > > > > > > > > > > > > > > Thanks > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > + > > > > > > > > > + err = vring_alloc_state_extra_split(&vring_split); > > > > > > > > > + if (err) { > > > > > > > > > + vring_free_split(&vring_split, vdev); > > > > > > > > > + goto err; > > > > > > > > > > > > > > > > > > > > > > > > I suggest to move vring_free_split() into a dedicated error label. > > > > > > > > > > > > > > Will change. > > > > > > > > > > > > > > Thanks. > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > Thanks > > > > > > > > > > > > > > > > > > > > > > > > > + } > > > > > > > > > + > > > > > > > > > + vring_free(&vq->vq); > > > > > > > > > + > > > > > > > > > + virtqueue_vring_init_split(&vring_split, vq); > > > > > > > > > + > > > > > > > > > + virtqueue_init(vq, vring_split.vring.num); > > > > > > > > > + virtqueue_vring_attach_split(vq, &vring_split); > > > > > > > > > + > > > > > > > > > + return 0; > > > > > > > > > + > > > > > > > > > +err: > > > > > > > > > + virtqueue_reinit_split(vq); > > > > > > > > > + return -ENOMEM; > > > > > > > > > +} > > > > > > > > > + > > > > > > > > > > > > > > > > > > /* > > > > > > > > > * Packed ring specific functions - *_packed(). > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > >
On Mon, 1 Aug 2022 12:49:12 +0800, Jason Wang <jasowang@redhat.com> wrote: > On Thu, Jul 28, 2022 at 7:27 PM Xuan Zhuo <xuanzhuo@linux.alibaba.com> wrote: > > > > On Thu, 28 Jul 2022 17:04:36 +0800, Jason Wang <jasowang@redhat.com> wrote: > > > On Thu, Jul 28, 2022 at 4:18 PM Xuan Zhuo <xuanzhuo@linux.alibaba.com> wrote: > > > > > > > > On Thu, 28 Jul 2022 15:42:50 +0800, Jason Wang <jasowang@redhat.com> wrote: > > > > > On Thu, Jul 28, 2022 at 3:24 PM Xuan Zhuo <xuanzhuo@linux.alibaba.com> wrote: > > > > > > > > > > > > On Thu, 28 Jul 2022 10:38:51 +0800, Jason Wang <jasowang@redhat.com> wrote: > > > > > > > On Wed, Jul 27, 2022 at 3:44 PM Xuan Zhuo <xuanzhuo@linux.alibaba.com> wrote: > > > > > > > > > > > > > > > > On Wed, 27 Jul 2022 11:12:19 +0800, Jason Wang <jasowang@redhat.com> wrote: > > > > > > > > > > > > > > > > > > 在 2022/7/26 15:21, Xuan Zhuo 写道: > > > > > > > > > > virtio ring split supports resize. > > > > > > > > > > > > > > > > > > > > Only after the new vring is successfully allocated based on the new num, > > > > > > > > > > we will release the old vring. In any case, an error is returned, > > > > > > > > > > indicating that the vring still points to the old vring. > > > > > > > > > > > > > > > > > > > > In the case of an error, re-initialize(virtqueue_reinit_split()) the > > > > > > > > > > virtqueue to ensure that the vring can be used. > > > > > > > > > > > > > > > > > > > > Signed-off-by: Xuan Zhuo <xuanzhuo@linux.alibaba.com> > > > > > > > > > > Acked-by: Jason Wang <jasowang@redhat.com> > > > > > > > > > > --- > > > > > > > > > > drivers/virtio/virtio_ring.c | 34 ++++++++++++++++++++++++++++++++++ > > > > > > > > > > 1 file changed, 34 insertions(+) > > > > > > > > > > > > > > > > > > > > diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c > > > > > > > > > > index b6fda91c8059..58355e1ac7d7 100644 > > > > > > > > > > --- a/drivers/virtio/virtio_ring.c > > > > > > > > > > +++ b/drivers/virtio/virtio_ring.c > > > > > > > > > > @@ -220,6 +220,7 @@ static struct virtqueue *__vring_new_virtqueue(unsigned int index, > > > > > > > > > > void (*callback)(struct virtqueue *), > > > > > > > > > > const char *name); > > > > > > > > > > static struct vring_desc_extra *vring_alloc_desc_extra(unsigned int num); > > > > > > > > > > +static void vring_free(struct virtqueue *_vq); > > > > > > > > > > > > > > > > > > > > /* > > > > > > > > > > * Helpers. > > > > > > > > > > @@ -1117,6 +1118,39 @@ static struct virtqueue *vring_create_virtqueue_split( > > > > > > > > > > return vq; > > > > > > > > > > } > > > > > > > > > > > > > > > > > > > > +static int virtqueue_resize_split(struct virtqueue *_vq, u32 num) > > > > > > > > > > +{ > > > > > > > > > > + struct vring_virtqueue_split vring_split = {}; > > > > > > > > > > + struct vring_virtqueue *vq = to_vvq(_vq); > > > > > > > > > > + struct virtio_device *vdev = _vq->vdev; > > > > > > > > > > + int err; > > > > > > > > > > + > > > > > > > > > > + err = vring_alloc_queue_split(&vring_split, vdev, num, > > > > > > > > > > + vq->split.vring_align, > > > > > > > > > > + vq->split.may_reduce_num); > > > > > > > > > > + if (err) > > > > > > > > > > + goto err; > > > > > > > > > > > > > > > > > > > > > > > > > > > I think we don't need to do anything here? > > > > > > > > > > > > > > > > Am I missing something? > > > > > > > > > > > > > > I meant it looks to me most of the virtqueue_reinit() is unnecessary. > > > > > > > We probably only need to reinit avail/used idx there. > > > > > > > > > > > > > > > > > > In this function, we can indeed remove some code. > > > > > > > > > > > > > static void virtqueue_reinit_split(struct vring_virtqueue *vq) > > > > > > > { > > > > > > > int size, i; > > > > > > > > > > > > > > memset(vq->split.vring.desc, 0, vq->split.queue_size_in_bytes); > > > > > > > > > > > > > > size = sizeof(struct vring_desc_state_split) * vq->split.vring.num; > > > > > > > memset(vq->split.desc_state, 0, size); > > > > > > > > > > > > > > size = sizeof(struct vring_desc_extra) * vq->split.vring.num; > > > > > > > memset(vq->split.desc_extra, 0, size); > > > > > > > > > > > > These memsets can be removed, and theoretically it will not cause any > > > > > > exceptions. > > > > > > > > > > Yes, otherwise we have bugs in detach_buf(). > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > for (i = 0; i < vq->split.vring.num - 1; i++) > > > > > > > vq->split.desc_extra[i].next = i + 1; > > > > > > > > > > > > This can also be removed, but we need to record free_head that will been update > > > > > > inside virtqueue_init(). > > > > > > > > > > We can simply keep free_head unchanged? Otherwise it's a bug somewhere I guess. > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > virtqueue_init(vq, vq->split.vring.num); > > > > > > > > > > > > There are some operations in this, which can also be skipped, such as setting > > > > > > use_dma_api. But I think calling this function directly will be more convenient > > > > > > for maintenance. > > > > > > > > > > I don't see anything that is necessary here. > > > > > > > > These three are currently inside virtqueue_init() > > > > > > > > vq->last_used_idx = 0; > > > > vq->event_triggered = false; > > > > vq->num_added = 0; > > > > > > Right. Let's keep it there. > > > > > > (Though it's kind of strange that the last_used_idx is not initialized > > > at the same place with avail_idx/flags_shadow, we can optimize it on > > > top). > > > > I put free_head = 0 in the attach function, it is only necessary to set > > free_head = 0 when a new state/extra is attached. > > Ok, so I meant I tend to keep it to make this series converge soon :) Ok, other than this, and what we discussed, no more fixes will be added. Thanks. > > We can do optimization on top anyhow. > > Thanks > > > > > In this way, when we call virtqueue_init(), we don't have to worry about > > free_head being modified. > > > > Rethinking this problem, I think virtqueue_init() can be rewritten and some > > variables that will not change are removed from it. (use_dma_api, event, > > weak_barriers) > > > > +static void virtqueue_init(struct vring_virtqueue *vq, u32 num) > > +{ > > + vq->vq.num_free = num; > > + > > + if (vq->packed_ring) > > + vq->last_used_idx = 0 | (1 << VRING_PACKED_EVENT_F_WRAP_CTR); > > + else > > + vq->last_used_idx = 0; > > + > > + vq->event_triggered = false; > > + vq->num_added = 0; > > + > > +#ifdef DEBUG > > + vq->in_use = false; > > + vq->last_add_time_valid = false; > > +#endif > > +} > > + > > > > Thanks. > > > > > > > > > > Thanks > > > > > > > > > > > Thanks. > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > virtqueue_vring_init_split(&vq->split, vq); > > > > > > > > > > > > virtqueue_vring_init_split() is necessary. > > > > > > > > > > Right. > > > > > > > > > > > > > > > > > > } > > > > > > > > > > > > Another method, we can take out all the variables to be reinitialized > > > > > > separately, and repackage them into a new function. I don’t think it’s worth > > > > > > it, because this path will only be reached if the memory allocation fails, which > > > > > > is a rare occurrence. In this case, doing so will increase the cost of > > > > > > maintenance. If you think so also, I will remove the above memset in the next > > > > > > version. > > > > > > > > > > I agree. > > > > > > > > > > Thanks > > > > > > > > > > > > > > > > > Thanks. > > > > > > > > > > > > > > > > > > > > > > > > > > Thanks > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > + > > > > > > > > > > + err = vring_alloc_state_extra_split(&vring_split); > > > > > > > > > > + if (err) { > > > > > > > > > > + vring_free_split(&vring_split, vdev); > > > > > > > > > > + goto err; > > > > > > > > > > > > > > > > > > > > > > > > > > > I suggest to move vring_free_split() into a dedicated error label. > > > > > > > > > > > > > > > > Will change. > > > > > > > > > > > > > > > > Thanks. > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > Thanks > > > > > > > > > > > > > > > > > > > > > > > > > > > > + } > > > > > > > > > > + > > > > > > > > > > + vring_free(&vq->vq); > > > > > > > > > > + > > > > > > > > > > + virtqueue_vring_init_split(&vring_split, vq); > > > > > > > > > > + > > > > > > > > > > + virtqueue_init(vq, vring_split.vring.num); > > > > > > > > > > + virtqueue_vring_attach_split(vq, &vring_split); > > > > > > > > > > + > > > > > > > > > > + return 0; > > > > > > > > > > + > > > > > > > > > > +err: > > > > > > > > > > + virtqueue_reinit_split(vq); > > > > > > > > > > + return -ENOMEM; > > > > > > > > > > +} > > > > > > > > > > + > > > > > > > > > > > > > > > > > > > > /* > > > > > > > > > > * Packed ring specific functions - *_packed(). > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > >
On Mon, Aug 1, 2022 at 2:13 PM Xuan Zhuo <xuanzhuo@linux.alibaba.com> wrote: > > On Mon, 1 Aug 2022 12:49:12 +0800, Jason Wang <jasowang@redhat.com> wrote: > > On Thu, Jul 28, 2022 at 7:27 PM Xuan Zhuo <xuanzhuo@linux.alibaba.com> wrote: > > > > > > On Thu, 28 Jul 2022 17:04:36 +0800, Jason Wang <jasowang@redhat.com> wrote: > > > > On Thu, Jul 28, 2022 at 4:18 PM Xuan Zhuo <xuanzhuo@linux.alibaba.com> wrote: > > > > > > > > > > On Thu, 28 Jul 2022 15:42:50 +0800, Jason Wang <jasowang@redhat.com> wrote: > > > > > > On Thu, Jul 28, 2022 at 3:24 PM Xuan Zhuo <xuanzhuo@linux.alibaba.com> wrote: > > > > > > > > > > > > > > On Thu, 28 Jul 2022 10:38:51 +0800, Jason Wang <jasowang@redhat.com> wrote: > > > > > > > > On Wed, Jul 27, 2022 at 3:44 PM Xuan Zhuo <xuanzhuo@linux.alibaba.com> wrote: > > > > > > > > > > > > > > > > > > On Wed, 27 Jul 2022 11:12:19 +0800, Jason Wang <jasowang@redhat.com> wrote: > > > > > > > > > > > > > > > > > > > > 在 2022/7/26 15:21, Xuan Zhuo 写道: > > > > > > > > > > > virtio ring split supports resize. > > > > > > > > > > > > > > > > > > > > > > Only after the new vring is successfully allocated based on the new num, > > > > > > > > > > > we will release the old vring. In any case, an error is returned, > > > > > > > > > > > indicating that the vring still points to the old vring. > > > > > > > > > > > > > > > > > > > > > > In the case of an error, re-initialize(virtqueue_reinit_split()) the > > > > > > > > > > > virtqueue to ensure that the vring can be used. > > > > > > > > > > > > > > > > > > > > > > Signed-off-by: Xuan Zhuo <xuanzhuo@linux.alibaba.com> > > > > > > > > > > > Acked-by: Jason Wang <jasowang@redhat.com> > > > > > > > > > > > --- > > > > > > > > > > > drivers/virtio/virtio_ring.c | 34 ++++++++++++++++++++++++++++++++++ > > > > > > > > > > > 1 file changed, 34 insertions(+) > > > > > > > > > > > > > > > > > > > > > > diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c > > > > > > > > > > > index b6fda91c8059..58355e1ac7d7 100644 > > > > > > > > > > > --- a/drivers/virtio/virtio_ring.c > > > > > > > > > > > +++ b/drivers/virtio/virtio_ring.c > > > > > > > > > > > @@ -220,6 +220,7 @@ static struct virtqueue *__vring_new_virtqueue(unsigned int index, > > > > > > > > > > > void (*callback)(struct virtqueue *), > > > > > > > > > > > const char *name); > > > > > > > > > > > static struct vring_desc_extra *vring_alloc_desc_extra(unsigned int num); > > > > > > > > > > > +static void vring_free(struct virtqueue *_vq); > > > > > > > > > > > > > > > > > > > > > > /* > > > > > > > > > > > * Helpers. > > > > > > > > > > > @@ -1117,6 +1118,39 @@ static struct virtqueue *vring_create_virtqueue_split( > > > > > > > > > > > return vq; > > > > > > > > > > > } > > > > > > > > > > > > > > > > > > > > > > +static int virtqueue_resize_split(struct virtqueue *_vq, u32 num) > > > > > > > > > > > +{ > > > > > > > > > > > + struct vring_virtqueue_split vring_split = {}; > > > > > > > > > > > + struct vring_virtqueue *vq = to_vvq(_vq); > > > > > > > > > > > + struct virtio_device *vdev = _vq->vdev; > > > > > > > > > > > + int err; > > > > > > > > > > > + > > > > > > > > > > > + err = vring_alloc_queue_split(&vring_split, vdev, num, > > > > > > > > > > > + vq->split.vring_align, > > > > > > > > > > > + vq->split.may_reduce_num); > > > > > > > > > > > + if (err) > > > > > > > > > > > + goto err; > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > I think we don't need to do anything here? > > > > > > > > > > > > > > > > > > Am I missing something? > > > > > > > > > > > > > > > > I meant it looks to me most of the virtqueue_reinit() is unnecessary. > > > > > > > > We probably only need to reinit avail/used idx there. > > > > > > > > > > > > > > > > > > > > > In this function, we can indeed remove some code. > > > > > > > > > > > > > > > static void virtqueue_reinit_split(struct vring_virtqueue *vq) > > > > > > > > { > > > > > > > > int size, i; > > > > > > > > > > > > > > > > memset(vq->split.vring.desc, 0, vq->split.queue_size_in_bytes); > > > > > > > > > > > > > > > > size = sizeof(struct vring_desc_state_split) * vq->split.vring.num; > > > > > > > > memset(vq->split.desc_state, 0, size); > > > > > > > > > > > > > > > > size = sizeof(struct vring_desc_extra) * vq->split.vring.num; > > > > > > > > memset(vq->split.desc_extra, 0, size); > > > > > > > > > > > > > > These memsets can be removed, and theoretically it will not cause any > > > > > > > exceptions. > > > > > > > > > > > > Yes, otherwise we have bugs in detach_buf(). > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > for (i = 0; i < vq->split.vring.num - 1; i++) > > > > > > > > vq->split.desc_extra[i].next = i + 1; > > > > > > > > > > > > > > This can also be removed, but we need to record free_head that will been update > > > > > > > inside virtqueue_init(). > > > > > > > > > > > > We can simply keep free_head unchanged? Otherwise it's a bug somewhere I guess. > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > virtqueue_init(vq, vq->split.vring.num); > > > > > > > > > > > > > > There are some operations in this, which can also be skipped, such as setting > > > > > > > use_dma_api. But I think calling this function directly will be more convenient > > > > > > > for maintenance. > > > > > > > > > > > > I don't see anything that is necessary here. > > > > > > > > > > These three are currently inside virtqueue_init() > > > > > > > > > > vq->last_used_idx = 0; > > > > > vq->event_triggered = false; > > > > > vq->num_added = 0; > > > > > > > > Right. Let's keep it there. > > > > > > > > (Though it's kind of strange that the last_used_idx is not initialized > > > > at the same place with avail_idx/flags_shadow, we can optimize it on > > > > top). > > > > > > I put free_head = 0 in the attach function, it is only necessary to set > > > free_head = 0 when a new state/extra is attached. > > > > Ok, so I meant I tend to keep it to make this series converge soon :) > > > Ok, other than this, and what we discussed, no more fixes will be added. > > Thanks. Ack Thanks > > > > > > We can do optimization on top anyhow. > > > > Thanks > > > > > > > > In this way, when we call virtqueue_init(), we don't have to worry about > > > free_head being modified. > > > > > > Rethinking this problem, I think virtqueue_init() can be rewritten and some > > > variables that will not change are removed from it. (use_dma_api, event, > > > weak_barriers) > > > > > > +static void virtqueue_init(struct vring_virtqueue *vq, u32 num) > > > +{ > > > + vq->vq.num_free = num; > > > + > > > + if (vq->packed_ring) > > > + vq->last_used_idx = 0 | (1 << VRING_PACKED_EVENT_F_WRAP_CTR); > > > + else > > > + vq->last_used_idx = 0; > > > + > > > + vq->event_triggered = false; > > > + vq->num_added = 0; > > > + > > > +#ifdef DEBUG > > > + vq->in_use = false; > > > + vq->last_add_time_valid = false; > > > +#endif > > > +} > > > + > > > > > > Thanks. > > > > > > > > > > > > > > Thanks > > > > > > > > > > > > > > Thanks. > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > virtqueue_vring_init_split(&vq->split, vq); > > > > > > > > > > > > > > virtqueue_vring_init_split() is necessary. > > > > > > > > > > > > Right. > > > > > > > > > > > > > > > > > > > > > } > > > > > > > > > > > > > > Another method, we can take out all the variables to be reinitialized > > > > > > > separately, and repackage them into a new function. I don’t think it’s worth > > > > > > > it, because this path will only be reached if the memory allocation fails, which > > > > > > > is a rare occurrence. In this case, doing so will increase the cost of > > > > > > > maintenance. If you think so also, I will remove the above memset in the next > > > > > > > version. > > > > > > > > > > > > I agree. > > > > > > > > > > > > Thanks > > > > > > > > > > > > > > > > > > > > Thanks. > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > Thanks > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > + > > > > > > > > > > > + err = vring_alloc_state_extra_split(&vring_split); > > > > > > > > > > > + if (err) { > > > > > > > > > > > + vring_free_split(&vring_split, vdev); > > > > > > > > > > > + goto err; > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > I suggest to move vring_free_split() into a dedicated error label. > > > > > > > > > > > > > > > > > > Will change. > > > > > > > > > > > > > > > > > > Thanks. > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > Thanks > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > + } > > > > > > > > > > > + > > > > > > > > > > > + vring_free(&vq->vq); > > > > > > > > > > > + > > > > > > > > > > > + virtqueue_vring_init_split(&vring_split, vq); > > > > > > > > > > > + > > > > > > > > > > > + virtqueue_init(vq, vring_split.vring.num); > > > > > > > > > > > + virtqueue_vring_attach_split(vq, &vring_split); > > > > > > > > > > > + > > > > > > > > > > > + return 0; > > > > > > > > > > > + > > > > > > > > > > > +err: > > > > > > > > > > > + virtqueue_reinit_split(vq); > > > > > > > > > > > + return -ENOMEM; > > > > > > > > > > > +} > > > > > > > > > > > + > > > > > > > > > > > > > > > > > > > > > > /* > > > > > > > > > > > * Packed ring specific functions - *_packed(). > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > >
diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c index b6fda91c8059..58355e1ac7d7 100644 --- a/drivers/virtio/virtio_ring.c +++ b/drivers/virtio/virtio_ring.c @@ -220,6 +220,7 @@ static struct virtqueue *__vring_new_virtqueue(unsigned int index, void (*callback)(struct virtqueue *), const char *name); static struct vring_desc_extra *vring_alloc_desc_extra(unsigned int num); +static void vring_free(struct virtqueue *_vq); /* * Helpers. @@ -1117,6 +1118,39 @@ static struct virtqueue *vring_create_virtqueue_split( return vq; } +static int virtqueue_resize_split(struct virtqueue *_vq, u32 num) +{ + struct vring_virtqueue_split vring_split = {}; + struct vring_virtqueue *vq = to_vvq(_vq); + struct virtio_device *vdev = _vq->vdev; + int err; + + err = vring_alloc_queue_split(&vring_split, vdev, num, + vq->split.vring_align, + vq->split.may_reduce_num); + if (err) + goto err; + + err = vring_alloc_state_extra_split(&vring_split); + if (err) { + vring_free_split(&vring_split, vdev); + goto err; + } + + vring_free(&vq->vq); + + virtqueue_vring_init_split(&vring_split, vq); + + virtqueue_init(vq, vring_split.vring.num); + virtqueue_vring_attach_split(vq, &vring_split); + + return 0; + +err: + virtqueue_reinit_split(vq); + return -ENOMEM; +} + /* * Packed ring specific functions - *_packed().