On Thu, Jul 22, 2021 at 3:44 AM Matthew Auld matthew.william.auld@gmail.com wrote:
On Wed, 21 Jul 2021 at 21:28, Jason Ekstrand jason@jlekstrand.net wrote:
On Thu, Jul 15, 2021 at 5:16 AM Matthew Auld matthew.auld@intel.com wrote:
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 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 PROPBE flag, so userspace can easily check if the kernel supports it(Jason).
- use mmap_read_{lock, unlock}.
- add some kernel-doc.
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
drivers/gpu/drm/i915/gem/i915_gem_userptr.c | 40 ++++++++++++++++++++- drivers/gpu/drm/i915/i915_getparam.c | 3 ++ include/uapi/drm/i915_drm.h | 18 ++++++++++ 3 files changed, 60 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..fd6880328596 100644 --- a/drivers/gpu/drm/i915/gem/i915_gem_userptr.c +++ b/drivers/gpu/drm/i915/gem/i915_gem_userptr.c @@ -422,6 +422,33 @@ 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) {if (vma->vm_start > addr)Why isn't this > end? Are we somehow guaranteed that one vma covers the entire range?
AFAIK we are just making sure we don't have a hole(note that we also update addr below), for example the user might have done a partial munmap. There could be multiple vma's if the kernel was unable to merge them. If we reach the vm_end >= end, then we know we have a "valid" range.
Ok. That wasn't obvious to me but I see the addr update now. Makes sense. Might be worth a one-line comment for the next guy. Either way,
Reviewed-by: Jason Ekstrand jason@jlekstrand.net
Thanks for wiring this up!
--Jason
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 +504,8 @@ 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 +532,16 @@ 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..d6d2e1a10d14 100644 --- a/drivers/gpu/drm/i915/i915_getparam.c +++ b/drivers/gpu/drm/i915/i915_getparam.c @@ -163,6 +163,9 @@ int i915_getparam_ioctl(struct drm_device *dev, void *data, case I915_PARAM_PERF_REVISION: value = i915_perf_ioctl_version(); break;
case I915_PARAM_HAS_USERPTR_PROBE:value = true;break; default: DRM_DEBUG("Unknown parameter %d\n", param->param); return -EINVAL;diff --git a/include/uapi/drm/i915_drm.h b/include/uapi/drm/i915_drm.h index e20eeeca7a1c..2e4112bf4d38 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 { @@ -2178,12 +2181,27 @@ 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.** 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
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