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...
Testcase: igt/gem_userptr_blits/probe
Signed-off-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
Cc: Tvrtko Ursulin <tvrtko.ursulin@xxxxxxxxx>
Cc: Michał Winiarski <michal.winiarski@xxxxxxxxx>
Cc: Jason Ekstrand <jason@xxxxxxxxxxxxxx>
---
drivers/gpu/drm/i915/i915_gem_userptr.c | 38 +++++++++++++++++++++++++++++++++
include/uapi/drm/i915_drm.h | 5 +++--
2 files changed, 41 insertions(+), 2 deletions(-)
diff --git a/drivers/gpu/drm/i915/i915_gem_userptr.c b/drivers/gpu/drm/i915/i915_gem_userptr.c
index e26b23171b56..dbc5818dd28b 100644
--- a/drivers/gpu/drm/i915/i915_gem_userptr.c
+++ b/drivers/gpu/drm/i915/i915_gem_userptr.c
@@ -719,6 +719,33 @@ static const struct drm_i915_gem_object_ops i915_gem_userptr_ops = {
.release = i915_gem_userptr_release,
};
+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;
+
+ down_read(&mm->mmap_sem);
+ for (vma = find_vma(mm, addr); vma; vma = vma->vm_next) {
+ 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;
+ }
+ up_read(&mm->mmap_sem);
+
+ return ret;
+}
+
/**
* Creates a new mm object that wraps some normal memory from the process
* context - user memory.
@@ -771,6 +798,7 @@ i915_gem_userptr_ioctl(struct drm_device *dev, void *data, struct drm_file *file
}
if (args->flags & ~(I915_USERPTR_READ_ONLY |
+ I915_USERPTR_PROBE |
I915_USERPTR_UNSYNCHRONIZED))
return -EINVAL;
@@ -788,6 +816,16 @@ i915_gem_userptr_ioctl(struct drm_device *dev, void *data, struct drm_file *file
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;
+ }
+
obj = i915_gem_object_alloc(dev_priv);
if (obj == NULL)
return -ENOMEM;
diff --git a/include/uapi/drm/i915_drm.h b/include/uapi/drm/i915_drm.h
index ac3c6503ca27..392ede2ca63e 100644
--- a/include/uapi/drm/i915_drm.h
+++ b/include/uapi/drm/i915_drm.h
@@ -1352,8 +1352,9 @@ struct drm_i915_gem_userptr {
__u64 user_ptr;
__u64 user_size;
__u32 flags;
-#define I915_USERPTR_READ_ONLY 0x1
-#define I915_USERPTR_UNSYNCHRONIZED 0x80000000
+#define I915_USERPTR_READ_ONLY 0x1
+#define I915_USERPTR_PROBE 0x2
+#define I915_USERPTR_UNSYNCHRONIZED 0x80000000
/**
* Returned handle for the object.
*
--
2.15.0
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