On Mon, 26 Jul 2021 at 17:10, Tvrtko Ursulin tvrtko.ursulin@linux.intel.com wrote:
On 26/07/2021 16:14, Jason Ekstrand wrote:
On Mon, Jul 26, 2021 at 3:31 AM Maarten Lankhorst maarten.lankhorst@linux.intel.com wrote:
Op 23-07-2021 om 13:34 schreef Matthew Auld:
From: Chris Wilson chris@chris-wilson.co.uk
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@chris-wilson.co.uk Signed-off-by: Matthew Auld matthew.auld@intel.com Cc: Thomas Hellström thomas.hellstrom@linux.intel.com Cc: Maarten Lankhorst maarten.lankhorst@linux.intel.com Cc: Tvrtko Ursulin tvrtko.ursulin@linux.intel.com Cc: Jordan Justen jordan.l.justen@intel.com Cc: Kenneth Graunke kenneth@whitecape.org Cc: Jason Ekstrand jason@jlekstrand.net Cc: Daniel Vetter daniel.vetter@ffwll.ch Cc: Ramalingam C ramalingam.c@intel.com Reviewed-by: Tvrtko Ursulin tvrtko.ursulin@intel.com Acked-by: Kenneth Graunke kenneth@whitecape.org Reviewed-by: Jason Ekstrand jason@jlekstrand.net
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 fromdiff --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_PROBE 0x2 #define I915_USERPTR_UNSYNCHRONIZED 0x80000000 /** * @handle: Returned handle for the object.
Could we use _VALIDATE instead of probe? Or at least pin the pages as well, so we don't have to do it later?
I only care that the name matches what it does. _VALIDATE sounds like it does a full validation of everything such that, if the import succeeds, execbuf will as well. If we pin the pages at the same time, maybe that's true? _PROBE, on the other hand, sounds a lot more like
No it is not possible to guarantee backing store remains valid until execbuf.
a one-time best-effort check which may race with other stuff and doesn't guarantee future success. That's in line with what the current patch does.
We already have i915_gem_object_userptr_validate, no need to dupe it.
I have no opinion on this.
I was actually suggesting the same as Maarten here - that we should add a "populate" flag. But opinion was that was not desired - please look for the older threads to see the reasoning there.
So how should we proceed here? Maarten?
Regards,
Tvrtko _______________________________________________ Intel-gfx mailing list Intel-gfx@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/intel-gfx