From: Ankitprasad Sharma <ankitprasad.r.sharma@xxxxxxxxx>
This patch adds support for extending the pread/pwrite functionality
for objects not backed by shmem. The access will be made through
gtt interface. This will cover objects backed by stolen memory as well
as other non-shmem backed objects.
v2: Drop locks around slow_user_access, prefault the pages before
access (Chris)
v3: Rebased to the latest drm-intel-nightly (Ankit)
v4: Moved page base & offset calculations outside the copy loop,
corrected data types for size and offset variables, corrected if-else
braces format (Tvrtko/kerneldocs)
v5: Enabled pread/pwrite for all non-shmem backed objects including
without tiling restrictions (Ankit)
v6: Using pwrite_fast for non-shmem backed objects as well (Chris)
v7: Updated commit message, Renamed i915_gem_gtt_read to
i915_gem_gtt_copy,
added pwrite slow path for non-shmem backed objects (Chris/Tvrtko)
v8: Updated v7 commit message, mutex unlock around pwrite slow path for
non-shmem backed objects (Tvrtko)
Testcase: igt/gem_stolen
Signed-off-by: Ankitprasad Sharma <ankitprasad.r.sharma@xxxxxxxxx>
---
drivers/gpu/drm/i915/i915_gem.c | 151
+++++++++++++++++++++++++++++++++-------
1 file changed, 127 insertions(+), 24 deletions(-)
diff --git a/drivers/gpu/drm/i915/i915_gem.c
b/drivers/gpu/drm/i915/i915_gem.c
index ed97de6..68ed67a 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -614,6 +614,99 @@ shmem_pread_slow(struct page *page, int
shmem_page_offset, int page_length,
return ret ? - EFAULT : 0;
}
+static inline uint64_t
+slow_user_access(struct io_mapping *mapping,
+ uint64_t page_base, int page_offset,
+ char __user *user_data,
+ int length, bool pwrite)
+{
+ void __iomem *vaddr_inatomic;
+ void *vaddr;
+ uint64_t unwritten;
+
+ vaddr_inatomic = io_mapping_map_wc(mapping, page_base);
+ /* We can use the cpu mem copy function because this is X86. */
+ vaddr = (void __force *)vaddr_inatomic + page_offset;
+ if (pwrite)
+ unwritten = __copy_from_user(vaddr, user_data, length);
+ else
+ unwritten = __copy_to_user(user_data, vaddr, length);
+
+ io_mapping_unmap(vaddr_inatomic);
+ return unwritten;
+}
+
+static int
+i915_gem_gtt_copy(struct drm_device *dev,
+ struct drm_i915_gem_object *obj, uint64_t size,
+ uint64_t data_offset, uint64_t data_ptr)
+{
+ struct drm_i915_private *dev_priv = dev->dev_private;
+ char __user *user_data;
+ uint64_t remain;
+ uint64_t offset, page_base;
+ int page_offset, page_length, ret = 0;
+
+ ret = i915_gem_obj_ggtt_pin(obj, 0, PIN_MAPPABLE);
+ if (ret)
+ goto out;
+
+ ret = i915_gem_object_set_to_gtt_domain(obj, false);
+ if (ret)
+ goto out_unpin;
+
+ ret = i915_gem_object_put_fence(obj);
+ if (ret)
+ goto out_unpin;
+
+ user_data = to_user_ptr(data_ptr);
+ remain = size;
+ offset = i915_gem_obj_ggtt_offset(obj) + data_offset;
+
+ mutex_unlock(&dev->struct_mutex);
+ if (likely(!i915.prefault_disable))
+ ret = fault_in_multipages_writeable(user_data, remain);
+
+ /*
+ * page_offset = offset within page
+ * page_base = page offset within aperture
+ */
+ page_offset = offset_in_page(offset);
+ page_base = offset & PAGE_MASK;
+
+ while (remain > 0) {
+ /* page_length = bytes to copy for this page */
+ page_length = remain;
+ if ((page_offset + remain) > PAGE_SIZE)
+ page_length = PAGE_SIZE - page_offset;
+
+ /* This is a slow read/write as it tries to read from
+ * and write to user memory which may result into page
+ * faults
+ */
+ ret = slow_user_access(dev_priv->gtt.mappable, page_base,
+ page_offset, user_data,
+ page_length, false);
+
+ if (ret) {
+ ret = -EFAULT;
+ break;
+ }
+
+ remain -= page_length;
+ user_data += page_length;
+ page_base += page_length;
+ page_offset = 0;
+ }
+
+ mutex_lock(&dev->struct_mutex);
+
+out_unpin:
+ i915_gem_object_ggtt_unpin(obj);
+out:
+ return ret;
+}
+
static int
i915_gem_shmem_pread(struct drm_device *dev,
struct drm_i915_gem_object *obj,
@@ -737,17 +830,14 @@ i915_gem_pread_ioctl(struct drm_device *dev,
void *data,
goto out;
}
- /* prime objects have no backing filp to GEM pread/pwrite
- * pages from.
- */
- if (!obj->base.filp) {
- ret = -EINVAL;
- goto out;
- }
-
trace_i915_gem_object_pread(obj, args->offset, args->size);
- ret = i915_gem_shmem_pread(dev, obj, args, file);
+ /* pread for non shmem backed objects */
+ if (!obj->base.filp && obj->tiling_mode == I915_TILING_NONE)
+ ret = i915_gem_gtt_copy(dev, obj, args->size,
+ args->offset, args->data_ptr);
+ else
+ ret = i915_gem_shmem_pread(dev, obj, args, file);
