* [PATCH 1/2] drm/virtio: cleanup queue functions [not found] <20190813082509.29324-1-kraxel@redhat.com> @ 2019-08-13 8:25 ` Gerd Hoffmann 2019-08-13 8:25 ` [PATCH 2/2] drm/virtio: notify virtqueues without holding spinlock Gerd Hoffmann 1 sibling, 0 replies; 3+ messages in thread From: Gerd Hoffmann @ 2019-08-13 8:25 UTC (permalink / raw) To: dri-devel Cc: olvaffe, Gerd Hoffmann, David Airlie, Daniel Vetter, open list:VIRTIO GPU DRIVER, open list Make the queue functions return void, none of the call sites checks the return value. Signed-off-by: Gerd Hoffmann <kraxel@redhat.com> --- drivers/gpu/drm/virtio/virtgpu_vq.c | 41 ++++++++++------------------- 1 file changed, 14 insertions(+), 27 deletions(-) diff --git a/drivers/gpu/drm/virtio/virtgpu_vq.c b/drivers/gpu/drm/virtio/virtgpu_vq.c index 7ac20490e1b4..ca91e83ffaef 100644 --- a/drivers/gpu/drm/virtio/virtgpu_vq.c +++ b/drivers/gpu/drm/virtio/virtgpu_vq.c @@ -252,8 +252,8 @@ void virtio_gpu_dequeue_cursor_func(struct work_struct *work) wake_up(&vgdev->cursorq.ack_queue); } -static int virtio_gpu_queue_ctrl_buffer_locked(struct virtio_gpu_device *vgdev, - struct virtio_gpu_vbuffer *vbuf) +static void virtio_gpu_queue_ctrl_buffer_locked(struct virtio_gpu_device *vgdev, + struct virtio_gpu_vbuffer *vbuf) __releases(&vgdev->ctrlq.qlock) __acquires(&vgdev->ctrlq.qlock) { @@ -263,7 +263,7 @@ static int virtio_gpu_queue_ctrl_buffer_locked(struct virtio_gpu_device *vgdev, int ret; if (!vgdev->vqs_ready) - return -ENODEV; + return; sg_init_one(&vcmd, vbuf->buf, vbuf->size); sgs[outcnt + incnt] = &vcmd; @@ -294,30 +294,22 @@ static int virtio_gpu_queue_ctrl_buffer_locked(struct virtio_gpu_device *vgdev, virtqueue_kick(vq); } - - if (!ret) - ret = vq->num_free; - return ret; } -static int virtio_gpu_queue_ctrl_buffer(struct virtio_gpu_device *vgdev, - struct virtio_gpu_vbuffer *vbuf) +static void virtio_gpu_queue_ctrl_buffer(struct virtio_gpu_device *vgdev, + struct virtio_gpu_vbuffer *vbuf) { - int rc; - spin_lock(&vgdev->ctrlq.qlock); - rc = virtio_gpu_queue_ctrl_buffer_locked(vgdev, vbuf); + virtio_gpu_queue_ctrl_buffer_locked(vgdev, vbuf); spin_unlock(&vgdev->ctrlq.qlock); - return rc; } -static int virtio_gpu_queue_fenced_ctrl_buffer(struct virtio_gpu_device *vgdev, - struct virtio_gpu_vbuffer *vbuf, - struct virtio_gpu_ctrl_hdr *hdr, - struct virtio_gpu_fence *fence) +static void virtio_gpu_queue_fenced_ctrl_buffer(struct virtio_gpu_device *vgdev, + struct virtio_gpu_vbuffer *vbuf, + struct virtio_gpu_ctrl_hdr *hdr, + struct virtio_gpu_fence *fence) { struct virtqueue *vq = vgdev->ctrlq.vq; - int rc; again: spin_lock(&vgdev->ctrlq.qlock); @@ -338,13 +330,12 @@ static int virtio_gpu_queue_fenced_ctrl_buffer(struct virtio_gpu_device *vgdev, if (fence) virtio_gpu_fence_emit(vgdev, hdr, fence); - rc = virtio_gpu_queue_ctrl_buffer_locked(vgdev, vbuf); + virtio_gpu_queue_ctrl_buffer_locked(vgdev, vbuf); spin_unlock(&vgdev->ctrlq.qlock); - return rc; } -static int virtio_gpu_queue_cursor(struct virtio_gpu_device *vgdev, - struct virtio_gpu_vbuffer *vbuf) +static void virtio_gpu_queue_cursor(struct virtio_gpu_device *vgdev, + struct virtio_gpu_vbuffer *vbuf) { struct virtqueue *vq = vgdev->cursorq.vq; struct scatterlist *sgs[1], ccmd; @@ -352,7 +343,7 @@ static int virtio_gpu_queue_cursor(struct virtio_gpu_device *vgdev, int outcnt; if (!vgdev->vqs_ready) - return -ENODEV; + return; sg_init_one(&ccmd, vbuf->buf, vbuf->size); sgs[0] = &ccmd; @@ -374,10 +365,6 @@ static int virtio_gpu_queue_cursor(struct virtio_gpu_device *vgdev, } spin_unlock(&vgdev->cursorq.qlock); - - if (!ret) - ret = vq->num_free; - return ret; } /* just create gem objects for userspace and long lived objects, -- 2.18.1 ^ permalink raw reply [flat|nested] 3+ messages in thread
* [PATCH 2/2] drm/virtio: notify virtqueues without holding spinlock [not found] <20190813082509.29324-1-kraxel@redhat.com> 2019-08-13 8:25 ` [PATCH 1/2] drm/virtio: cleanup queue functions Gerd Hoffmann @ 2019-08-13 8:25 ` Gerd Hoffmann 2019-08-27 16:45 ` Chia-I Wu 1 sibling, 1 reply; 3+ messages in thread From: Gerd Hoffmann @ 2019-08-13 8:25 UTC (permalink / raw) To: dri-devel Cc: olvaffe, Gerd Hoffmann, David Airlie, Daniel Vetter, open list:VIRTIO GPU DRIVER, open list Split virtqueue_kick() call into virtqueue_kick_prepare(), which requires serialization, and virtqueue_notify(), which does not. Move the virtqueue_notify() call out of the critical section protected by the queue lock. This avoids triggering a vmexit while holding the lock and thereby fixes a rather bad spinlock contention. Suggested-by: Chia-I Wu <olvaffe@gmail.com> Signed-off-by: Gerd Hoffmann <kraxel@redhat.com> --- drivers/gpu/drm/virtio/virtgpu_vq.c | 25 +++++++++++++++++++------ 1 file changed, 19 insertions(+), 6 deletions(-) diff --git a/drivers/gpu/drm/virtio/virtgpu_vq.c b/drivers/gpu/drm/virtio/virtgpu_vq.c index ca91e83ffaef..e41c96143342 100644 --- a/drivers/gpu/drm/virtio/virtgpu_vq.c +++ b/drivers/gpu/drm/virtio/virtgpu_vq.c @@ -252,7 +252,7 @@ void virtio_gpu_dequeue_cursor_func(struct work_struct *work) wake_up(&vgdev->cursorq.ack_queue); } -static void virtio_gpu_queue_ctrl_buffer_locked(struct virtio_gpu_device *vgdev, +static bool virtio_gpu_queue_ctrl_buffer_locked(struct virtio_gpu_device *vgdev, struct virtio_gpu_vbuffer *vbuf) __releases(&vgdev->ctrlq.qlock) __acquires(&vgdev->ctrlq.qlock) @@ -260,10 +260,11 @@ static void virtio_gpu_queue_ctrl_buffer_locked(struct virtio_gpu_device *vgdev, struct virtqueue *vq = vgdev->ctrlq.vq; struct scatterlist *sgs[3], vcmd, vout, vresp; int outcnt = 0, incnt = 0; + bool notify = false; int ret; if (!vgdev->vqs_ready) - return; + return notify; sg_init_one(&vcmd, vbuf->buf, vbuf->size); sgs[outcnt + incnt] = &vcmd; @@ -292,16 +293,21 @@ static void virtio_gpu_queue_ctrl_buffer_locked(struct virtio_gpu_device *vgdev, trace_virtio_gpu_cmd_queue(vq, (struct virtio_gpu_ctrl_hdr *)vbuf->buf); - virtqueue_kick(vq); + notify = virtqueue_kick_prepare(vq); } + return notify; } static void virtio_gpu_queue_ctrl_buffer(struct virtio_gpu_device *vgdev, struct virtio_gpu_vbuffer *vbuf) { + bool notify; + spin_lock(&vgdev->ctrlq.qlock); - virtio_gpu_queue_ctrl_buffer_locked(vgdev, vbuf); + notify = virtio_gpu_queue_ctrl_buffer_locked(vgdev, vbuf); spin_unlock(&vgdev->ctrlq.qlock); + if (notify) + virtqueue_notify(vgdev->ctrlq.vq); } static void virtio_gpu_queue_fenced_ctrl_buffer(struct virtio_gpu_device *vgdev, @@ -310,6 +316,7 @@ static void virtio_gpu_queue_fenced_ctrl_buffer(struct virtio_gpu_device *vgdev, struct virtio_gpu_fence *fence) { struct virtqueue *vq = vgdev->ctrlq.vq; + bool notify; again: spin_lock(&vgdev->ctrlq.qlock); @@ -330,8 +337,10 @@ static void virtio_gpu_queue_fenced_ctrl_buffer(struct virtio_gpu_device *vgdev, if (fence) virtio_gpu_fence_emit(vgdev, hdr, fence); - virtio_gpu_queue_ctrl_buffer_locked(vgdev, vbuf); + notify = virtio_gpu_queue_ctrl_buffer_locked(vgdev, vbuf); spin_unlock(&vgdev->ctrlq.qlock); + if (notify) + virtqueue_notify(vgdev->ctrlq.vq); } static void virtio_gpu_queue_cursor(struct virtio_gpu_device *vgdev, @@ -339,6 +348,7 @@ static void virtio_gpu_queue_cursor(struct virtio_gpu_device *vgdev, { struct virtqueue *vq = vgdev->cursorq.vq; struct scatterlist *sgs[1], ccmd; + bool notify; int ret; int outcnt; @@ -361,10 +371,13 @@ static void virtio_gpu_queue_cursor(struct virtio_gpu_device *vgdev, trace_virtio_gpu_cmd_queue(vq, (struct virtio_gpu_ctrl_hdr *)vbuf->buf); - virtqueue_kick(vq); + notify = virtqueue_kick_prepare(vq); } spin_unlock(&vgdev->cursorq.qlock); + + if (notify) + virtqueue_notify(vq); } /* just create gem objects for userspace and long lived objects, -- 2.18.1 ^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH 2/2] drm/virtio: notify virtqueues without holding spinlock 2019-08-13 8:25 ` [PATCH 2/2] drm/virtio: notify virtqueues without holding spinlock Gerd Hoffmann @ 2019-08-27 16:45 ` Chia-I Wu 0 siblings, 0 replies; 3+ messages in thread From: Chia-I Wu @ 2019-08-27 16:45 UTC (permalink / raw) To: Gerd Hoffmann Cc: ML dri-devel, David Airlie, Daniel Vetter, open list:VIRTIO GPU DRIVER, open list On Tue, Aug 13, 2019 at 1:25 AM Gerd Hoffmann <kraxel@redhat.com> wrote: > > Split virtqueue_kick() call into virtqueue_kick_prepare(), which > requires serialization, and virtqueue_notify(), which does not. Move > the virtqueue_notify() call out of the critical section protected by the > queue lock. This avoids triggering a vmexit while holding the lock and > thereby fixes a rather bad spinlock contention. > > Suggested-by: Chia-I Wu <olvaffe@gmail.com> > Signed-off-by: Gerd Hoffmann <kraxel@redhat.com> Series is Reviewed-by: Chia-I Wu <olvaffe@gmail.com> > --- > drivers/gpu/drm/virtio/virtgpu_vq.c | 25 +++++++++++++++++++------ > 1 file changed, 19 insertions(+), 6 deletions(-) > > diff --git a/drivers/gpu/drm/virtio/virtgpu_vq.c b/drivers/gpu/drm/virtio/virtgpu_vq.c > index ca91e83ffaef..e41c96143342 100644 > --- a/drivers/gpu/drm/virtio/virtgpu_vq.c > +++ b/drivers/gpu/drm/virtio/virtgpu_vq.c > @@ -252,7 +252,7 @@ void virtio_gpu_dequeue_cursor_func(struct work_struct *work) > wake_up(&vgdev->cursorq.ack_queue); > } > > -static void virtio_gpu_queue_ctrl_buffer_locked(struct virtio_gpu_device *vgdev, > +static bool virtio_gpu_queue_ctrl_buffer_locked(struct virtio_gpu_device *vgdev, > struct virtio_gpu_vbuffer *vbuf) > __releases(&vgdev->ctrlq.qlock) > __acquires(&vgdev->ctrlq.qlock) > @@ -260,10 +260,11 @@ static void virtio_gpu_queue_ctrl_buffer_locked(struct virtio_gpu_device *vgdev, > struct virtqueue *vq = vgdev->ctrlq.vq; > struct scatterlist *sgs[3], vcmd, vout, vresp; > int outcnt = 0, incnt = 0; > + bool notify = false; > int ret; > > if (!vgdev->vqs_ready) > - return; > + return notify; > > sg_init_one(&vcmd, vbuf->buf, vbuf->size); > sgs[outcnt + incnt] = &vcmd; > @@ -292,16 +293,21 @@ static void virtio_gpu_queue_ctrl_buffer_locked(struct virtio_gpu_device *vgdev, > trace_virtio_gpu_cmd_queue(vq, > (struct virtio_gpu_ctrl_hdr *)vbuf->buf); > > - virtqueue_kick(vq); > + notify = virtqueue_kick_prepare(vq); > } > + return notify; > } > > static void virtio_gpu_queue_ctrl_buffer(struct virtio_gpu_device *vgdev, > struct virtio_gpu_vbuffer *vbuf) > { > + bool notify; > + > spin_lock(&vgdev->ctrlq.qlock); > - virtio_gpu_queue_ctrl_buffer_locked(vgdev, vbuf); > + notify = virtio_gpu_queue_ctrl_buffer_locked(vgdev, vbuf); > spin_unlock(&vgdev->ctrlq.qlock); > + if (notify) > + virtqueue_notify(vgdev->ctrlq.vq); > } > > static void virtio_gpu_queue_fenced_ctrl_buffer(struct virtio_gpu_device *vgdev, > @@ -310,6 +316,7 @@ static void virtio_gpu_queue_fenced_ctrl_buffer(struct virtio_gpu_device *vgdev, > struct virtio_gpu_fence *fence) > { > struct virtqueue *vq = vgdev->ctrlq.vq; > + bool notify; > > again: > spin_lock(&vgdev->ctrlq.qlock); > @@ -330,8 +337,10 @@ static void virtio_gpu_queue_fenced_ctrl_buffer(struct virtio_gpu_device *vgdev, > > if (fence) > virtio_gpu_fence_emit(vgdev, hdr, fence); > - virtio_gpu_queue_ctrl_buffer_locked(vgdev, vbuf); > + notify = virtio_gpu_queue_ctrl_buffer_locked(vgdev, vbuf); > spin_unlock(&vgdev->ctrlq.qlock); > + if (notify) > + virtqueue_notify(vgdev->ctrlq.vq); > } > > static void virtio_gpu_queue_cursor(struct virtio_gpu_device *vgdev, > @@ -339,6 +348,7 @@ static void virtio_gpu_queue_cursor(struct virtio_gpu_device *vgdev, > { > struct virtqueue *vq = vgdev->cursorq.vq; > struct scatterlist *sgs[1], ccmd; > + bool notify; > int ret; > int outcnt; > > @@ -361,10 +371,13 @@ static void virtio_gpu_queue_cursor(struct virtio_gpu_device *vgdev, > trace_virtio_gpu_cmd_queue(vq, > (struct virtio_gpu_ctrl_hdr *)vbuf->buf); > > - virtqueue_kick(vq); > + notify = virtqueue_kick_prepare(vq); > } > > spin_unlock(&vgdev->cursorq.qlock); > + > + if (notify) > + virtqueue_notify(vq); > } > > /* just create gem objects for userspace and long lived objects, > -- > 2.18.1 > ^ permalink raw reply [flat|nested] 3+ messages in thread
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2019-08-13 8:25 ` [PATCH 1/2] drm/virtio: cleanup queue functions Gerd Hoffmann
2019-08-13 8:25 ` [PATCH 2/2] drm/virtio: notify virtqueues without holding spinlock Gerd Hoffmann
2019-08-27 16:45 ` Chia-I Wu
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