* [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 related [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 related [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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[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 ` [PATCH 2/2] drm/virtio: notify virtqueues without holding spinlock Gerd Hoffmann
2019-08-27 16:45 ` Chia-I Wu
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