Hi Gurchetan,
>
> Similar to DRM_VMW_EVENT_FENCE_SIGNALED. Sends a pollable event
> to the DRM file descriptor when a fence on a specific ring is
> signaled.
>
> One difference is the event is not exposed via the UAPI -- this is
> because host responses are on a shared memory buffer of type
> BLOB_MEM_GUEST [this is the common way to receive responses with
> virtgpu]. As such, there is no context specific read(..)
> implementation either -- just a poll(..) implementation.
[Kasireddy, Vivek] Given my limited understanding of virtio_gpu 3D/Virgl, I am
wondering why you'd need a new internal event associated with a fence; would
you not be able to accomplish the same by adding the out_fence_fd (from execbuf)
to your userspace's event loop (in addition to DRM fd) and get signalled?
Thanks,
Vivek
>
> Signed-off-by: Gurchetan Singh <gurchetansi...@chromium.org>
> Acked-by: Nicholas Verne <nve...@chromium.org>
> ---
> drivers/gpu/drm/virtio/virtgpu_drv.c | 43 +++++++++++++++++++++++++-
> drivers/gpu/drm/virtio/virtgpu_drv.h | 7 +++++
> drivers/gpu/drm/virtio/virtgpu_fence.c | 10 ++++++
> drivers/gpu/drm/virtio/virtgpu_ioctl.c | 34 ++++++++++++++++++++
> 4 files changed, 93 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/virtio/virtgpu_drv.c
> b/drivers/gpu/drm/virtio/virtgpu_drv.c
> index 9d963f1fda8f..749db18dcfa2 100644
> --- a/drivers/gpu/drm/virtio/virtgpu_drv.c
> +++ b/drivers/gpu/drm/virtio/virtgpu_drv.c
> @@ -29,6 +29,8 @@
> #include <linux/module.h>
> #include <linux/console.h>
> #include <linux/pci.h>
> +#include <linux/poll.h>
> +#include <linux/wait.h>
>
> #include <drm/drm.h>
> #include <drm/drm_aperture.h>
> @@ -155,6 +157,35 @@ static void virtio_gpu_config_changed(struct
> virtio_device
> *vdev)
> schedule_work(&vgdev->config_changed_work);
> }
>
> +static __poll_t virtio_gpu_poll(struct file *filp,
> + struct poll_table_struct *wait)
> +{
> + struct drm_file *drm_file = filp->private_data;
> + struct virtio_gpu_fpriv *vfpriv = drm_file->driver_priv;
> + struct drm_device *dev = drm_file->minor->dev;
> + struct drm_pending_event *e = NULL;
> + __poll_t mask = 0;
> +
> + if (!vfpriv->ring_idx_mask)
> + return drm_poll(filp, wait);
> +
> + poll_wait(filp, &drm_file->event_wait, wait);
> +
> + if (!list_empty(&drm_file->event_list)) {
> + spin_lock_irq(&dev->event_lock);
> + e = list_first_entry(&drm_file->event_list,
> + struct drm_pending_event, link);
> + drm_file->event_space += e->event->length;
> + list_del(&e->link);
> + spin_unlock_irq(&dev->event_lock);
> +
> + kfree(e);
> + mask |= EPOLLIN | EPOLLRDNORM;
> + }
> +
> + return mask;
> +}
> +
> static struct virtio_device_id id_table[] = {
> { VIRTIO_ID_GPU, VIRTIO_DEV_ANY_ID },
> { 0 },
> @@ -194,7 +225,17 @@ MODULE_AUTHOR("Dave Airlie <airl...@redhat.com>");
> MODULE_AUTHOR("Gerd Hoffmann <kra...@redhat.com>");
> MODULE_AUTHOR("Alon Levy");
>
> -DEFINE_DRM_GEM_FOPS(virtio_gpu_driver_fops);
> +static const struct file_operations virtio_gpu_driver_fops = {
> + .owner = THIS_MODULE,
> + .open = drm_open,
> + .release = drm_release,
> + .unlocked_ioctl = drm_ioctl,
> + .compat_ioctl = drm_compat_ioctl,
> + .poll = virtio_gpu_poll,
> + .read = drm_read,
> + .llseek = noop_llseek,
> + .mmap = drm_gem_mmap
> +};
>
> static const struct drm_driver driver = {
> .driver_features = DRIVER_MODESET | DRIVER_GEM | DRIVER_RENDER |
> DRIVER_ATOMIC,
> diff --git a/drivers/gpu/drm/virtio/virtgpu_drv.h
> b/drivers/gpu/drm/virtio/virtgpu_drv.h
> index cb60d52c2bd1..e0265fe74aa5 100644
> --- a/drivers/gpu/drm/virtio/virtgpu_drv.h
> +++ b/drivers/gpu/drm/virtio/virtgpu_drv.h
> @@ -138,11 +138,18 @@ struct virtio_gpu_fence_driver {
> spinlock_t lock;
> };
>
> +#define VIRTGPU_EVENT_FENCE_SIGNALED_INTERNAL 0x10000000
> +struct virtio_gpu_fence_event {
> + struct drm_pending_event base;
> + struct drm_event event;
> +};
> +
> struct virtio_gpu_fence {
> struct dma_fence f;
> uint32_t ring_idx;
> uint64_t fence_id;
> bool emit_fence_info;
> + struct virtio_gpu_fence_event *e;
> struct virtio_gpu_fence_driver *drv;
> struct list_head node;
> };
> diff --git a/drivers/gpu/drm/virtio/virtgpu_fence.c
> b/drivers/gpu/drm/virtio/virtgpu_fence.c
> index 98a00c1e654d..f28357dbde35 100644
> --- a/drivers/gpu/drm/virtio/virtgpu_fence.c
> +++ b/drivers/gpu/drm/virtio/virtgpu_fence.c
> @@ -152,11 +152,21 @@ void virtio_gpu_fence_event_process(struct
> virtio_gpu_device
> *vgdev,
> continue;
>
> dma_fence_signal_locked(&curr->f);
> + if (curr->e) {
> + drm_send_event(vgdev->ddev, &curr->e->base);
> + curr->e = NULL;
> + }
> +
> list_del(&curr->node);
> dma_fence_put(&curr->f);
> }
>
> dma_fence_signal_locked(&signaled->f);
> + if (signaled->e) {
> + drm_send_event(vgdev->ddev, &signaled->e->base);
> + signaled->e = NULL;
> + }
> +
> list_del(&signaled->node);
> dma_fence_put(&signaled->f);
> break;
> diff --git a/drivers/gpu/drm/virtio/virtgpu_ioctl.c
> b/drivers/gpu/drm/virtio/virtgpu_ioctl.c
> index be7b22a03884..fdaa7f3d9eeb 100644
> --- a/drivers/gpu/drm/virtio/virtgpu_ioctl.c
> +++ b/drivers/gpu/drm/virtio/virtgpu_ioctl.c
> @@ -38,6 +38,36 @@
> VIRTGPU_BLOB_FLAG_USE_SHAREABLE | \
> VIRTGPU_BLOB_FLAG_USE_CROSS_DEVICE)
>
> +static int virtio_gpu_fence_event_create(struct drm_device *dev,
> + struct drm_file *file,
> + struct virtio_gpu_fence *fence,
> + uint32_t ring_idx)
> +{
> + struct virtio_gpu_fpriv *vfpriv = file->driver_priv;
> + struct virtio_gpu_fence_event *e = NULL;
> + int ret;
> +
> + if (!(vfpriv->ring_idx_mask & (1 << ring_idx)))
> + return 0;
> +
> + e = kzalloc(sizeof(*e), GFP_KERNEL);
> + if (!e)
> + return -ENOMEM;
> +
> + e->event.type = VIRTGPU_EVENT_FENCE_SIGNALED_INTERNAL;
> + e->event.length = sizeof(e->event);
> +
> + ret = drm_event_reserve_init(dev, file, &e->base, &e->event);
> + if (ret)
> + goto free;
> +
> + fence->e = e;
> + return 0;
> +free:
> + kfree(e);
> + return ret;
> +}
> +
> /* Must be called with &virtio_gpu_fpriv.struct_mutex held. */
> static void virtio_gpu_create_context_locked(struct virtio_gpu_device *vgdev,
> struct virtio_gpu_fpriv *vfpriv)
> @@ -195,6 +225,10 @@ static int virtio_gpu_execbuffer_ioctl(struct drm_device
> *dev,
> void *data,
> goto out_unresv;
> }
>
> + ret = virtio_gpu_fence_event_create(dev, file, out_fence, ring_idx);
> + if (ret)
> + goto out_unresv;
> +
> if (out_fence_fd >= 0) {
> sync_file = sync_file_create(&out_fence->f);
> if (!sync_file) {
> --
> 2.33.0.464.g1972c5931b-goog
