Re: [PATCH 2/2] drm/msm: Add MSM_WAIT_IOVA ioctl

From: Rob Clark
Date: Mon Jan 13 2020 - 11:25:35 EST

On Mon, Jan 13, 2020 at 7:37 AM Brian Ho <brian@xxxxxxxxx> wrote:
>
> Implements an ioctl to wait until a value at a given iova is greater
> than or equal to a supplied value.
>
> This will initially be used by turnip (open-source Vulkan driver for
> QC in mesa) for occlusion queries where the userspace driver can
> block on a query becoming available before continuing via
> vkGetQueryPoolResults.
>
> Signed-off-by: Brian Ho <brian@xxxxxxxxx>
> ---
> drivers/gpu/drm/msm/msm_drv.c | 63 +++++++++++++++++++++++++++++++++--
> include/uapi/drm/msm_drm.h | 13 ++++++++
> 2 files changed, 74 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/gpu/drm/msm/msm_drv.c b/drivers/gpu/drm/msm/msm_drv.c
> index c84f0a8b3f2c..dcc46874a5a2 100644
> --- a/drivers/gpu/drm/msm/msm_drv.c
> +++ b/drivers/gpu/drm/msm/msm_drv.c
> @@ -36,10 +36,11 @@
> * MSM_GEM_INFO ioctl.
> * - 1.4.0 - softpin, MSM_RELOC_BO_DUMP, and GEM_INFO support to set/get
> * GEM object's debug name
> - * - 1.5.0 - Add SUBMITQUERY_QUERY ioctl
> + * - 1.5.0 - Add SUBMITQUEUE_QUERY ioctl
> + * - 1.6.0 - Add WAIT_IOVA ioctl
> */
> #define MSM_VERSION_MAJOR 1
> -#define MSM_VERSION_MINOR 5
> +#define MSM_VERSION_MINOR 6
> #define MSM_VERSION_PATCHLEVEL 0
>
> static const struct drm_mode_config_funcs mode_config_funcs = {
> @@ -952,6 +953,63 @@ static int msm_ioctl_submitqueue_close(struct drm_device *dev, void *data,
> return msm_submitqueue_remove(file->driver_priv, id);
> }
>
> +static int msm_ioctl_wait_iova(struct drm_device *dev, void *data,
> + struct drm_file *file)
> +{
> + struct msm_drm_private *priv = dev->dev_private;
> + struct drm_gem_object *obj;
> + struct drm_msm_wait_iova *args = data;
> + ktime_t timeout = to_ktime(args->timeout);
> + unsigned long remaining_jiffies = timeout_to_jiffies(&timeout);
> + struct msm_gpu *gpu = priv->gpu;
> + void *base_vaddr;
> + uint64_t *vaddr;
> + int ret;
> +
> + if (args->pad)
> + return -EINVAL;
> +
> + if (!gpu)
> + return 0;

hmm, I'm not sure we should return zero in this case.. maybe -ENODEV?

> +
> + obj = drm_gem_object_lookup(file, args->handle);
> + if (!obj)
> + return -ENOENT;
> +
> + base_vaddr = msm_gem_get_vaddr(obj);
> + if (IS_ERR(base_vaddr)) {
> + ret = PTR_ERR(base_vaddr);
> + goto err_put_gem_object;
> + }
> + if (args->offset + sizeof(*vaddr) > obj->size) {
> + ret = -EINVAL;
> + goto err_put_vaddr;
> + }
> +
> + vaddr = base_vaddr + args->offset;
> +
> + /* Assumes WC mapping */
> + ret = wait_event_interruptible_timeout(
> + gpu->event, *vaddr >= args->value, remaining_jiffies);
> +
> + if (ret == 0) {
> + ret = -ETIMEDOUT;
> + goto err_put_vaddr;
> + } else if (ret == -ERESTARTSYS) {
> + goto err_put_vaddr;
> + }

maybe:

} else {
ret = 0;
}

and then drop the next three lines?

> +
> + msm_gem_put_vaddr(obj);
> + drm_gem_object_put_unlocked(obj);
> + return 0;
> +
> +err_put_vaddr:
> + msm_gem_put_vaddr(obj);
> +err_put_gem_object:
> + drm_gem_object_put_unlocked(obj);
> + return ret;
> +}
> +
> static const struct drm_ioctl_desc msm_ioctls[] = {
> DRM_IOCTL_DEF_DRV(MSM_GET_PARAM, msm_ioctl_get_param, DRM_RENDER_ALLOW),
> DRM_IOCTL_DEF_DRV(MSM_GEM_NEW, msm_ioctl_gem_new, DRM_RENDER_ALLOW),
> @@ -964,6 +1022,7 @@ static const struct drm_ioctl_desc msm_ioctls[] = {
> DRM_IOCTL_DEF_DRV(MSM_SUBMITQUEUE_NEW, msm_ioctl_submitqueue_new, DRM_RENDER_ALLOW),
> DRM_IOCTL_DEF_DRV(MSM_SUBMITQUEUE_CLOSE, msm_ioctl_submitqueue_close, DRM_RENDER_ALLOW),
> DRM_IOCTL_DEF_DRV(MSM_SUBMITQUEUE_QUERY, msm_ioctl_submitqueue_query, DRM_RENDER_ALLOW),
> + DRM_IOCTL_DEF_DRV(MSM_WAIT_IOVA, msm_ioctl_wait_iova, DRM_RENDER_ALLOW),
> };
>
> static const struct vm_operations_struct vm_ops = {
> diff --git a/include/uapi/drm/msm_drm.h b/include/uapi/drm/msm_drm.h
> index 0b85ed6a3710..8477f28a4ee1 100644
> --- a/include/uapi/drm/msm_drm.h
> +++ b/include/uapi/drm/msm_drm.h
> @@ -298,6 +298,17 @@ struct drm_msm_submitqueue_query {
> __u32 pad;
> };
>
> +/* This ioctl blocks until the u64 value at bo + offset is greater than or
> + * equal to the reference value.
> + */
> +struct drm_msm_wait_iova {
> + __u32 handle; /* in, GEM handle */
> + __u32 pad;
> + struct drm_msm_timespec timeout; /* in */
> + __u64 offset; /* offset into bo */
> + __u64 value; /* reference value */

Maybe we should go ahead and add a __u64 mask;

that would let us wait for 32b values as well, and wait for bits in a bitmask

Other than those minor comments, it looks pretty good to me

BR,
-R

> +};
> +
> #define DRM_MSM_GET_PARAM 0x00
> /* placeholder:
> #define DRM_MSM_SET_PARAM 0x01
> @@ -315,6 +326,7 @@ struct drm_msm_submitqueue_query {
> #define DRM_MSM_SUBMITQUEUE_NEW 0x0A
> #define DRM_MSM_SUBMITQUEUE_CLOSE 0x0B
> #define DRM_MSM_SUBMITQUEUE_QUERY 0x0C
> +#define DRM_MSM_WAIT_IOVA 0x0D
>
> #define DRM_IOCTL_MSM_GET_PARAM DRM_IOWR(DRM_COMMAND_BASE + DRM_MSM_GET_PARAM, struct drm_msm_param)
> #define DRM_IOCTL_MSM_GEM_NEW DRM_IOWR(DRM_COMMAND_BASE + DRM_MSM_GEM_NEW, struct drm_msm_gem_new)
> @@ -327,6 +339,7 @@ struct drm_msm_submitqueue_query {
> #define DRM_IOCTL_MSM_SUBMITQUEUE_NEW DRM_IOWR(DRM_COMMAND_BASE + DRM_MSM_SUBMITQUEUE_NEW, struct drm_msm_submitqueue)
> #define DRM_IOCTL_MSM_SUBMITQUEUE_CLOSE DRM_IOW (DRM_COMMAND_BASE + DRM_MSM_SUBMITQUEUE_CLOSE, __u32)
> #define DRM_IOCTL_MSM_SUBMITQUEUE_QUERY DRM_IOW (DRM_COMMAND_BASE + DRM_MSM_SUBMITQUEUE_QUERY, struct drm_msm_submitqueue_query)
> +#define DRM_IOCTL_MSM_WAIT_IOVA DRM_IOW (DRM_COMMAND_BASE + DRM_MSM_WAIT_IOVA, struct drm_msm_wait_iova)
>
> #if defined(__cplusplus)
> }
> --
> 2.25.0.rc1.283.g88dfdc4193-goog
>