[9/9] drm/msm: Add a way for userspace to allocate GPU iova

From: Rob Clark <robdclark@chromium.org>

The motivation at this point is mainly native userspace mesa driver in a
VM guest.  The one remaining synchronous "hotpath" is buffer allocation,
because guest needs to wait to know the bo's iova before it can start
emitting cmdstream/state that references the new bo.  By allocating the
iova in the guest userspace, we no longer need to wait for a response
from the host, but can just rely on the allocation request being
processed before the cmdstream submission.  Allocation faulures (OoM,
etc) would just be treated as context-lost (ie. GL_GUILTY_CONTEXT_RESET)
or subsequent allocations (or readpix, etc) can raise GL_OUT_OF_MEMORY.

Signed-off-by: Rob Clark <robdclark@chromium.org>
---
 drivers/gpu/drm/msm/adreno/adreno_gpu.c | 10 ++++++
 drivers/gpu/drm/msm/msm_drv.c           | 21 +++++++++++
 drivers/gpu/drm/msm/msm_gem.c           | 48 +++++++++++++++++++++++++
 drivers/gpu/drm/msm/msm_gem.h           |  8 +++++
 drivers/gpu/drm/msm/msm_gem_vma.c       |  2 ++
 include/uapi/drm/msm_drm.h              |  3 ++
 6 files changed, 92 insertions(+)

On 3/30/22 02:00, Rob Clark wrote:
> +static int msm_ioctl_gem_info_set_iova(struct drm_device *dev,
> +		struct drm_file *file, struct drm_gem_object *obj,
> +		uint64_t iova)
> +{
> +	struct msm_drm_private *priv = dev->dev_private;
> +	struct msm_file_private *ctx = file->driver_priv;
> +
> +	if (!priv->gpu)
> +		return -EINVAL;
> +
> +	/* Only supported if per-process address space is supported: */
> +	if (priv->gpu->aspace == ctx->aspace)
> +		return -EINVAL;

nit: -EOPNOTSUPP ?

On Tue, Mar 29, 2022 at 4:42 PM Dmitry Baryshkov
<dmitry.baryshkov@linaro.org> wrote:
>
> On Wed, 30 Mar 2022 at 02:00, Rob Clark <robdclark@gmail.com> wrote:
> >
> > From: Rob Clark <robdclark@chromium.org>
> >
> > The motivation at this point is mainly native userspace mesa driver in a
> > VM guest.  The one remaining synchronous "hotpath" is buffer allocation,
> > because guest needs to wait to know the bo's iova before it can start
> > emitting cmdstream/state that references the new bo.  By allocating the
> > iova in the guest userspace, we no longer need to wait for a response
> > from the host, but can just rely on the allocation request being
> > processed before the cmdstream submission.  Allocation faulures (OoM,
>
> failures
>
> > etc) would just be treated as context-lost (ie. GL_GUILTY_CONTEXT_RESET)
> > or subsequent allocations (or readpix, etc) can raise GL_OUT_OF_MEMORY.
> >
> > Signed-off-by: Rob Clark <robdclark@chromium.org>
>
> Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
>
> Minor nits (above and below).
>
> > ---
> >  drivers/gpu/drm/msm/adreno/adreno_gpu.c | 10 ++++++
> >  drivers/gpu/drm/msm/msm_drv.c           | 21 +++++++++++
> >  drivers/gpu/drm/msm/msm_gem.c           | 48 +++++++++++++++++++++++++
> >  drivers/gpu/drm/msm/msm_gem.h           |  8 +++++
> >  drivers/gpu/drm/msm/msm_gem_vma.c       |  2 ++
> >  include/uapi/drm/msm_drm.h              |  3 ++
> >  6 files changed, 92 insertions(+)
> >
> > diff --git a/drivers/gpu/drm/msm/adreno/adreno_gpu.c b/drivers/gpu/drm/msm/adreno/adreno_gpu.c
> > index 6385ab06632f..4caae0229518 100644
> > --- a/drivers/gpu/drm/msm/adreno/adreno_gpu.c
> > +++ b/drivers/gpu/drm/msm/adreno/adreno_gpu.c
> > @@ -281,6 +281,16 @@ int adreno_get_param(struct msm_gpu *gpu, struct msm_file_private *ctx,
> >         case MSM_PARAM_SUSPENDS:
> >                 *value = gpu->suspend_count;
> >                 return 0;
> > +       case MSM_PARAM_VA_START:
> > +               if (ctx->aspace == gpu->aspace)
> > +                       return -EINVAL;
> > +               *value = ctx->aspace->va_start;
> > +               return 0;
> > +       case MSM_PARAM_VA_SIZE:
> > +               if (ctx->aspace == gpu->aspace)
> > +                       return -EINVAL;
> > +               *value = ctx->aspace->va_size;
> > +               return 0;
> >         default:
> >                 DBG("%s: invalid param: %u", gpu->name, param);
> >                 return -EINVAL;
> > diff --git a/drivers/gpu/drm/msm/msm_drv.c b/drivers/gpu/drm/msm/msm_drv.c
> > index a5eed5738ac8..7394312cf075 100644
> > --- a/drivers/gpu/drm/msm/msm_drv.c
> > +++ b/drivers/gpu/drm/msm/msm_drv.c
> > @@ -719,6 +719,23 @@ static int msm_ioctl_gem_info_iova(struct drm_device *dev,
> >         return msm_gem_get_iova(obj, ctx->aspace, iova);
> >  }
> >
> > +static int msm_ioctl_gem_info_set_iova(struct drm_device *dev,
> > +               struct drm_file *file, struct drm_gem_object *obj,
> > +               uint64_t iova)
> > +{
> > +       struct msm_drm_private *priv = dev->dev_private;
> > +       struct msm_file_private *ctx = file->driver_priv;
> > +
> > +       if (!priv->gpu)
> > +               return -EINVAL;
> > +
> > +       /* Only supported if per-process address space is supported: */
> > +       if (priv->gpu->aspace == ctx->aspace)
> > +               return -EINVAL;
> > +
> > +       return msm_gem_set_iova(obj, ctx->aspace, iova);
> > +}
> > +
> >  static int msm_ioctl_gem_info(struct drm_device *dev, void *data,
> >                 struct drm_file *file)
> >  {
> > @@ -733,6 +750,7 @@ static int msm_ioctl_gem_info(struct drm_device *dev, void *data,
> >         switch (args->info) {
> >         case MSM_INFO_GET_OFFSET:
> >         case MSM_INFO_GET_IOVA:
> > +       case MSM_INFO_SET_IOVA:
> >                 /* value returned as immediate, not pointer, so len==0: */
> >                 if (args->len)
> >                         return -EINVAL;
> > @@ -757,6 +775,9 @@ static int msm_ioctl_gem_info(struct drm_device *dev, void *data,
> >         case MSM_INFO_GET_IOVA:
> >                 ret = msm_ioctl_gem_info_iova(dev, file, obj, &args->value);
> >                 break;
> > +       case MSM_INFO_SET_IOVA:
> > +               ret = msm_ioctl_gem_info_set_iova(dev, file, obj, args->value);
> > +               break;
> >         case MSM_INFO_SET_NAME:
> >                 /* length check should leave room for terminating null: */
> >                 if (args->len >= sizeof(msm_obj->name)) {
> > diff --git a/drivers/gpu/drm/msm/msm_gem.c b/drivers/gpu/drm/msm/msm_gem.c
> > index bf4af17e2f1e..3122ba308f31 100644
> > --- a/drivers/gpu/drm/msm/msm_gem.c
> > +++ b/drivers/gpu/drm/msm/msm_gem.c
> > @@ -525,6 +525,54 @@ int msm_gem_get_iova(struct drm_gem_object *obj,
> >         return ret;
> >  }
> >
> > +static int clear_iova(struct drm_gem_object *obj,
> > +                     struct msm_gem_address_space *aspace)
> > +{
> > +       struct msm_gem_vma *vma = lookup_vma(obj, aspace);
> > +
> > +       if (!vma)
> > +               return 0;
> > +
> > +       if (vma->inuse)
>
> msm_gem_vma_inuse() ?

Ahh, right, this was the exact motivation for msm_gem_vma_inuse() and
ofc I miss it while rebasing ;-)

And -EOPNOTSUPP elsewhere is a good idea.. I've fixed both locally,
and the commit msg.  Thanks!

BR,
-R

> > +               return -EBUSY;
> > +
> > +       msm_gem_purge_vma(vma->aspace, vma);
> > +       msm_gem_close_vma(vma->aspace, vma);
> > +       del_vma(vma);
> > +
> > +       return 0;
> > +}
> > +
> > +/*
> > + * Get the requested iova but don't pin it.  Fails if the requested iova is
> > + * not available.  Doesn't need a put because iovas are currently valid for
> > + * the life of the object.
> > + *
> > + * Setting an iova of zero will clear the vma.
> > + */
> > +int msm_gem_set_iova(struct drm_gem_object *obj,
> > +                    struct msm_gem_address_space *aspace, uint64_t iova)
> > +{
> > +       int ret = 0;
> > +
> > +       msm_gem_lock(obj);
> > +       if (!iova) {
> > +               ret = clear_iova(obj, aspace);
> > +       } else {
> > +               struct msm_gem_vma *vma;
> > +               vma = get_vma_locked(obj, aspace, iova, iova + obj->size);
> > +               if (IS_ERR(vma)) {
> > +                       ret = PTR_ERR(vma);
> > +               } else if (GEM_WARN_ON(vma->iova != iova)) {
> > +                       clear_iova(obj, aspace);
> > +                       ret = -ENOSPC;
> > +               }
> > +       }
> > +       msm_gem_unlock(obj);
> > +
> > +       return ret;
> > +}
> > +
> >  /*
> >   * Unpin a iova by updating the reference counts. The memory isn't actually
> >   * purged until something else (shrinker, mm_notifier, destroy, etc) decides
> > diff --git a/drivers/gpu/drm/msm/msm_gem.h b/drivers/gpu/drm/msm/msm_gem.h
> > index 38d66e1248b1..efa2e5c19f1e 100644
> > --- a/drivers/gpu/drm/msm/msm_gem.h
> > +++ b/drivers/gpu/drm/msm/msm_gem.h
> > @@ -38,6 +38,12 @@ struct msm_gem_address_space {
> >
> >         /* @faults: the number of GPU hangs associated with this address space */
> >         int faults;
> > +
> > +       /** @va_start: lowest possible address to allocate */
> > +       uint64_t va_start;
> > +
> > +       /** @va_size: the size of the address space (in bytes) */
> > +       uint64_t va_size;
> >  };
> >
> >  struct msm_gem_address_space *
> > @@ -144,6 +150,8 @@ struct msm_gem_vma *msm_gem_get_vma_locked(struct drm_gem_object *obj,
> >                                            struct msm_gem_address_space *aspace);
> >  int msm_gem_get_iova(struct drm_gem_object *obj,
> >                 struct msm_gem_address_space *aspace, uint64_t *iova);
> > +int msm_gem_set_iova(struct drm_gem_object *obj,
> > +               struct msm_gem_address_space *aspace, uint64_t iova);
> >  int msm_gem_get_and_pin_iova_range(struct drm_gem_object *obj,
> >                 struct msm_gem_address_space *aspace, uint64_t *iova,
> >                 u64 range_start, u64 range_end);
> > diff --git a/drivers/gpu/drm/msm/msm_gem_vma.c b/drivers/gpu/drm/msm/msm_gem_vma.c
> > index 6f9a402450f9..354f91aff573 100644
> > --- a/drivers/gpu/drm/msm/msm_gem_vma.c
> > +++ b/drivers/gpu/drm/msm/msm_gem_vma.c
> > @@ -182,6 +182,8 @@ msm_gem_address_space_create(struct msm_mmu *mmu, const char *name,
> >         spin_lock_init(&aspace->lock);
> >         aspace->name = name;
> >         aspace->mmu = mmu;
> > +       aspace->va_start = va_start;
> > +       aspace->va_size  = size;
> >
> >         drm_mm_init(&aspace->mm, va_start, size);
> >
> > diff --git a/include/uapi/drm/msm_drm.h b/include/uapi/drm/msm_drm.h
> > index 794ad1948497..3c7b097c4e3d 100644
> > --- a/include/uapi/drm/msm_drm.h
> > +++ b/include/uapi/drm/msm_drm.h
> > @@ -84,6 +84,8 @@ struct drm_msm_timespec {
> >  #define MSM_PARAM_SYSPROF    0x0b  /* WO: 1 preserves perfcntrs, 2 also disables suspend */
> >  #define MSM_PARAM_COMM       0x0c  /* WO: override for task->comm */
> >  #define MSM_PARAM_CMDLINE    0x0d  /* WO: override for task cmdline */
> > +#define MSM_PARAM_VA_START   0x0e  /* RO: start of valid GPU iova range */
> > +#define MSM_PARAM_VA_SIZE    0x0f  /* RO: size of valid GPU iova range (bytes) */
> >
> >  /* For backwards compat.  The original support for preemption was based on
> >   * a single ring per priority level so # of priority levels equals the #
> > @@ -135,6 +137,7 @@ struct drm_msm_gem_new {
> >  #define MSM_INFO_GET_IOVA      0x01   /* get iova, returned by value */
> >  #define MSM_INFO_SET_NAME      0x02   /* set the debug name (by pointer) */
> >  #define MSM_INFO_GET_NAME      0x03   /* get debug name, returned by pointer */
> > +#define MSM_INFO_SET_IOVA      0x04   /* set the iova, passed by value */
> >
> >  struct drm_msm_gem_info {
> >         __u32 handle;         /* in */
> > --
> > 2.35.1
> >
>
>
> --
> With best wishes
> Dmitry