[PATCH 1/3] drm/amdgpu: Add interface to protect VRAM at exact position

[Horace Chen]

The existing method to reserve specified VRAM is to create a bo on
system domain then pin it to VRAM. But in this process the existing
data on the VRAM will be broken, because ttm will allocate a zero
buffer on system domain then copy the zeroes to VRAM.

Actually SRIOV need to reserve VRAM to protect data at exact
position.

So here add a new interface to create bo at the exact position
directly and then pin it immediately to avoid eviction and avoid
breaking the existing data on the VRAM.

Signed-off-by: Horace Chen <horace.chen at amd.com>
---
 drivers/gpu/drm/amd/amdgpu/amdgpu_object.c | 84 ++++++++++++++++++++++++++++--
 drivers/gpu/drm/amd/amdgpu/amdgpu_object.h |  4 ++
 2 files changed, 85 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_object.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_object.c
index e44b880..7108dc5 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_object.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_object.c
@@ -281,7 +281,7 @@ void amdgpu_bo_free_kernel(struct amdgpu_bo **bo, u64 *gpu_addr,
 		*cpu_addr = NULL;
 }
 
-static int amdgpu_bo_do_create(struct amdgpu_device *adev,
+static int amdgpu_bo_do_create(struct amdgpu_device *adev, u64 offset,
 			       unsigned long size, int byte_align,
 			       bool kernel, u32 domain, u64 flags,
 			       struct sg_table *sg,
@@ -295,6 +295,7 @@ static int amdgpu_bo_do_create(struct amdgpu_device *adev,
 	u64 initial_bytes_moved, bytes_moved;
 	size_t acc_size;
 	int r;
+	int i;
 
 	page_align = roundup(byte_align, PAGE_SIZE) >> PAGE_SHIFT;
 	size = ALIGN(size, PAGE_SIZE);
@@ -364,6 +365,21 @@ static int amdgpu_bo_do_create(struct amdgpu_device *adev,
 	bo->tbo.bdev = &adev->mman.bdev;
 	amdgpu_ttm_placement_from_domain(bo, domain);
 
+	/*
+	 * if offset is not ~0, it means the offset of this bo is restricted.
+	 * modify the placement to create bo at the exact place.
+	 */
+	if (((domain & AMDGPU_GEM_DOMAIN_VRAM) ||
+	    (domain & AMDGPU_GEM_DOMAIN_GTT)) && offset != ~0) {
+		offset = ALIGN(offset, PAGE_SIZE);
+		for (i = 0; i < bo->placement.num_placement; ++i) {
+			bo->placements[i].fpfn =
+			    offset >> PAGE_SHIFT;
+			bo->placements[i].lpfn =
+			    (offset + size) >> PAGE_SHIFT;
+		}
+	}
+
 	initial_bytes_moved = atomic64_read(&adev->num_bytes_moved);
 	/* Kernel allocation are uninterruptible */
 	r = ttm_bo_init_reserved(&adev->mman.bdev, &bo->tbo, size, type,
@@ -416,6 +432,68 @@ static int amdgpu_bo_do_create(struct amdgpu_device *adev,
 	return r;
 }
 
+/**
+ * amdgpu_bo_create_vram_restricted_kernel -
+ *    create BO at the specified place on the VRAM.
+ *
+ * @adev: amdgpu device object
+ * @offset: start offset of the new BO
+ * @size: size for the new BO
+ * @byte_align: alignment for the new BO
+ * @flags: addition flags for the BO
+ * @bo_ptr: resulting BO
+ * @gpu_addr: GPU addr of the pinned BO
+ * @cpu_addr: optional CPU address mapping
+ *
+ * Allocates and pins a BO at the specified place on the VRAM.
+ *
+ * Returns 0 on success, negative error code otherwise.
+ */
+int amdgpu_bo_create_vram_restricted_kernel(struct amdgpu_device *adev,
+		     u64 offset, unsigned long size, int byte_align,
+		     u64 flags, struct amdgpu_bo **bo_ptr,
+		     u64 *gpu_addr, void **cpu_addr)
+{
+	int r;
+	/* specified memory must be in contiguous*/
+	flags |= AMDGPU_GEM_CREATE_VRAM_CONTIGUOUS;
+
+	r = amdgpu_bo_do_create(adev, offset, size, byte_align, true,
+		AMDGPU_GEM_DOMAIN_VRAM, flags, NULL, NULL, 0, bo_ptr);
+	if (r)
+		return r;
+
+	r = amdgpu_bo_reserve(*bo_ptr, false);
+	if (r)
+		goto error_reserve;
+	r = amdgpu_bo_pin_restricted(*bo_ptr,
+		AMDGPU_GEM_DOMAIN_VRAM, offset, (offset + size),
+		gpu_addr);
+	if (r)
+		goto error_pin;
+	if (cpu_addr) {
+		r = amdgpu_bo_kmap(*bo_ptr,
+					cpu_addr);
+		if (r)
+			goto error_kmap;
+	}
+
+	amdgpu_bo_unreserve(*bo_ptr);
+
+	return r;
+error_kmap:
+	amdgpu_bo_unpin(*bo_ptr);
+error_pin:
+	amdgpu_bo_unreserve(*bo_ptr);
+error_reserve:
+	amdgpu_bo_unref(bo_ptr);
+	if (cpu_addr)
+		*cpu_addr = NULL;
+	if (gpu_addr)
+		*gpu_addr = 0;
+	return r;
+}
+
 static int amdgpu_bo_create_shadow(struct amdgpu_device *adev,
 				   unsigned long size, int byte_align,
 				   struct amdgpu_bo *bo)
@@ -425,7 +503,7 @@ static int amdgpu_bo_create_shadow(struct amdgpu_device *adev,
 	if (bo->shadow)
 		return 0;
 
-	r = amdgpu_bo_do_create(adev, size, byte_align, true,
+	r = amdgpu_bo_do_create(adev, ~0, size, byte_align, true,
 				AMDGPU_GEM_DOMAIN_GTT,
 				AMDGPU_GEM_CREATE_CPU_GTT_USWC |
 				AMDGPU_GEM_CREATE_SHADOW,
@@ -455,7 +533,7 @@ int amdgpu_bo_create(struct amdgpu_device *adev,
 	uint64_t parent_flags = flags & ~AMDGPU_GEM_CREATE_SHADOW;
 	int r;
 
-	r = amdgpu_bo_do_create(adev, size, byte_align, kernel, domain,
+	r = amdgpu_bo_do_create(adev, ~0, size, byte_align, kernel, domain,
 				parent_flags, sg, resv, init_value, bo_ptr);
 	if (r)
 		return r;
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_object.h b/drivers/gpu/drm/amd/amdgpu/amdgpu_object.h
index 33615e2..71f4f82 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_object.h
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_object.h
@@ -216,6 +216,10 @@ int amdgpu_bo_create_kernel(struct amdgpu_device *adev,
 			    unsigned long size, int align,
 			    u32 domain, struct amdgpu_bo **bo_ptr,
 			    u64 *gpu_addr, void **cpu_addr);
+int amdgpu_bo_create_vram_restricted_kernel(struct amdgpu_device *adev,
+			     u64 offset, unsigned long size, int byte_align,
+			     u64 flags, struct amdgpu_bo **bo_ptr,
+			     u64 *gpu_addr, void **cpu_addr);
 void amdgpu_bo_free_kernel(struct amdgpu_bo **bo, u64 *gpu_addr,
 			   void **cpu_addr);
 int amdgpu_bo_kmap(struct amdgpu_bo *bo, void **ptr);
-- 
2.7.4