https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/12044 On Fri, Jul 23, 2021 at 6:35 AM Matthew Auld <matthew.auld@xxxxxxxxx> wrote: > > From: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx> > > Jason Ekstrand requested a more efficient method than userptr+set-domain > to determine if the userptr object was backed by a complete set of pages > upon creation. To be more efficient than simply populating the userptr > using get_user_pages() (as done by the call to set-domain or execbuf), > we can walk the tree of vm_area_struct and check for gaps or vma not > backed by struct page (VM_PFNMAP). The question is how to handle > VM_MIXEDMAP which may be either struct page or pfn backed... > > With discrete we are going to drop support for set_domain(), so offering > a way to probe the pages, without having to resort to dummy batches has > been requested. > > v2: > - add new query param for the PROBE flag, so userspace can easily > check if the kernel supports it(Jason). > - use mmap_read_{lock, unlock}. > - add some kernel-doc. > v3: > - In the docs also mention that PROBE doesn't guarantee that the pages > will remain valid by the time they are actually used(Tvrtko). > - Add a small comment for the hole finding logic(Jason). > - Move the param next to all the other params which just return true. > > Testcase: igt/gem_userptr_blits/probe > Signed-off-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx> > Signed-off-by: Matthew Auld <matthew.auld@xxxxxxxxx> > Cc: Thomas Hellström <thomas.hellstrom@xxxxxxxxxxxxxxx> > Cc: Maarten Lankhorst <maarten.lankhorst@xxxxxxxxxxxxxxx> > Cc: Tvrtko Ursulin <tvrtko.ursulin@xxxxxxxxxxxxxxx> > Cc: Jordan Justen <jordan.l.justen@xxxxxxxxx> > Cc: Kenneth Graunke <kenneth@xxxxxxxxxxxxx> > Cc: Jason Ekstrand <jason@xxxxxxxxxxxxxx> > Cc: Daniel Vetter <daniel.vetter@xxxxxxxx> > Cc: Ramalingam C <ramalingam.c@xxxxxxxxx> > Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@xxxxxxxxx> > Acked-by: Kenneth Graunke <kenneth@xxxxxxxxxxxxx> > Reviewed-by: Jason Ekstrand <jason@xxxxxxxxxxxxxx> > --- > drivers/gpu/drm/i915/gem/i915_gem_userptr.c | 41 ++++++++++++++++++++- > drivers/gpu/drm/i915/i915_getparam.c | 1 + > include/uapi/drm/i915_drm.h | 20 ++++++++++ > 3 files changed, 61 insertions(+), 1 deletion(-) > > diff --git a/drivers/gpu/drm/i915/gem/i915_gem_userptr.c b/drivers/gpu/drm/i915/gem/i915_gem_userptr.c > index 56edfeff8c02..468a7a617fbf 100644 > --- a/drivers/gpu/drm/i915/gem/i915_gem_userptr.c > +++ b/drivers/gpu/drm/i915/gem/i915_gem_userptr.c > @@ -422,6 +422,34 @@ static const struct drm_i915_gem_object_ops i915_gem_userptr_ops = { > > #endif > > +static int > +probe_range(struct mm_struct *mm, unsigned long addr, unsigned long len) > +{ > + const unsigned long end = addr + len; > + struct vm_area_struct *vma; > + int ret = -EFAULT; > + > + mmap_read_lock(mm); > + for (vma = find_vma(mm, addr); vma; vma = vma->vm_next) { > + /* Check for holes, note that we also update the addr below */ > + if (vma->vm_start > addr) > + break; > + > + if (vma->vm_flags & (VM_PFNMAP | VM_MIXEDMAP)) > + break; > + > + if (vma->vm_end >= end) { > + ret = 0; > + break; > + } > + > + addr = vma->vm_end; > + } > + mmap_read_unlock(mm); > + > + return ret; > +} > + > /* > * Creates a new mm object that wraps some normal memory from the process > * context - user memory. > @@ -477,7 +505,8 @@ i915_gem_userptr_ioctl(struct drm_device *dev, > } > > if (args->flags & ~(I915_USERPTR_READ_ONLY | > - I915_USERPTR_UNSYNCHRONIZED)) > + I915_USERPTR_UNSYNCHRONIZED | > + I915_USERPTR_PROBE)) > return -EINVAL; > > if (i915_gem_object_size_2big(args->user_size)) > @@ -504,6 +533,16 @@ i915_gem_userptr_ioctl(struct drm_device *dev, > return -ENODEV; > } > > + if (args->flags & I915_USERPTR_PROBE) { > + /* > + * Check that the range pointed to represents real struct > + * pages and not iomappings (at this moment in time!) > + */ > + ret = probe_range(current->mm, args->user_ptr, args->user_size); > + if (ret) > + return ret; > + } > + > #ifdef CONFIG_MMU_NOTIFIER > obj = i915_gem_object_alloc(); > if (obj == NULL) > diff --git a/drivers/gpu/drm/i915/i915_getparam.c b/drivers/gpu/drm/i915/i915_getparam.c > index 24e18219eb50..bbb7cac43eb4 100644 > --- a/drivers/gpu/drm/i915/i915_getparam.c > +++ b/drivers/gpu/drm/i915/i915_getparam.c > @@ -134,6 +134,7 @@ int i915_getparam_ioctl(struct drm_device *dev, void *data, > case I915_PARAM_HAS_EXEC_FENCE_ARRAY: > case I915_PARAM_HAS_EXEC_SUBMIT_FENCE: > case I915_PARAM_HAS_EXEC_TIMELINE_FENCES: > + case I915_PARAM_HAS_USERPTR_PROBE: > /* For the time being all of these are always true; > * if some supported hardware does not have one of these > * features this value needs to be provided from > diff --git a/include/uapi/drm/i915_drm.h b/include/uapi/drm/i915_drm.h > index 975087553ea0..0d290535a6e5 100644 > --- a/include/uapi/drm/i915_drm.h > +++ b/include/uapi/drm/i915_drm.h > @@ -674,6 +674,9 @@ typedef struct drm_i915_irq_wait { > */ > #define I915_PARAM_HAS_EXEC_TIMELINE_FENCES 55 > > +/* Query if the kernel supports the I915_USERPTR_PROBE flag. */ > +#define I915_PARAM_HAS_USERPTR_PROBE 56 > + > /* Must be kept compact -- no holes and well documented */ > > typedef struct drm_i915_getparam { > @@ -2222,12 +2225,29 @@ struct drm_i915_gem_userptr { > * through the GTT. If the HW can't support readonly access, an error is > * returned. > * > + * I915_USERPTR_PROBE: > + * > + * Probe the provided @user_ptr range and validate that the @user_ptr is > + * indeed pointing to normal memory and that the range is also valid. > + * For example if some garbage address is given to the kernel, then this > + * should complain. > + * > + * Returns -EFAULT if the probe failed. > + * > + * Note that this doesn't populate the backing pages, and also doesn't > + * guarantee that the object will remain valid when the object is > + * eventually used. > + * > + * The kernel supports this feature if I915_PARAM_HAS_USERPTR_PROBE > + * returns a non-zero value. > + * > * I915_USERPTR_UNSYNCHRONIZED: > * > * NOT USED. Setting this flag will result in an error. > */ > __u32 flags; > #define I915_USERPTR_READ_ONLY 0x1 > +#define I915_USERPTR_PROBE 0x2 > #define I915_USERPTR_UNSYNCHRONIZED 0x80000000 > /** > * @handle: Returned handle for the object. > -- > 2.26.3 >
