Re: [PATCH 1/2] drm/amdgpu: Use fw vram offset when allocating stolen vga memory.

[Christian König]

Am 14.03.22 um 19:54 schrieb Yongqiang Sun:
[Why]
Memory access violation will happen in case of allocate stolen vga
memory with size isn't 0.
[How]
when allocating stolen vga memory, use fw vram offset as the start point
instead of hard code value 0.

Please stop separating commit message into [Why] and [How], that is not 
well received everywhere.

Apart from that the patch is a certain NAK, you are messing things quite 
up here.


Signed-off-by: Yongqiang Sun <yongqiang....@amd.com>
Change-Id: I7c555a6c1fb4b3fa8685753b4bdcbe215f89ea1e
---
  drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c | 31 +++++++++++++++++++------
  1 file changed, 24 insertions(+), 7 deletions(-)

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c 
b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
index 41d6f604813d..1f635fdb0395 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
@@ -1708,6 +1708,7 @@ int amdgpu_ttm_init(struct amdgpu_device *adev)
        uint64_t gtt_size;
        int r;
        u64 vis_vram_limit;
+       u64 memory_offset = adev->mman.fw_vram_usage_start_offset + 
adev->mman.fw_vram_usage_size;
  
  	mutex_init(&adev->mman.gtt_window_lock);
  
@@ -1774,24 +1775,40 @@ int amdgpu_ttm_init(struct amdgpu_device *adev)
         * This is used for VGA emulation and pre-OS scanout buffers to
         * avoid display artifacts while transitioning between pre-OS
         * and driver.  */
-       r = amdgpu_bo_create_kernel_at(adev, 0, adev->mman.stolen_vga_size,
+       r = amdgpu_bo_create_kernel_at(adev,
+                                          memory_offset,
+                                  adev->mman.stolen_vga_size,

That is certainly incorrect. See function amdgpu_ttm_fw_reserve_vram_init().

The stolen VGA buffer always started at offset 0 and is independent of 
the range defined by fw_vram_usage_start_offset and fw_vram_usage_size.

Regards,
Christian.

                                       AMDGPU_GEM_DOMAIN_VRAM,
                                       &adev->mman.stolen_vga_memory,
                                       NULL);
        if (r)
                return r;
-       r = amdgpu_bo_create_kernel_at(adev, adev->mman.stolen_vga_size,
+
+       memory_offset += adev->mman.stolen_vga_size;
+
+       r = amdgpu_bo_create_kernel_at(adev,
+                                          memory_offset,
                                       adev->mman.stolen_extended_size,
                                       AMDGPU_GEM_DOMAIN_VRAM,
                                       &adev->mman.stolen_extended_memory,
                                       NULL);
        if (r)
                return r;
-       r = amdgpu_bo_create_kernel_at(adev, adev->mman.stolen_reserved_offset,
-                                      adev->mman.stolen_reserved_size,
-                                      AMDGPU_GEM_DOMAIN_VRAM,
-                                      &adev->mman.stolen_reserved_memory,
-                                      NULL);
+
+       memory_offset += adev->mman.stolen_extended_size;
+
+       if (adev->mman.stolen_reserved_offset > memory_offset)
+               r = amdgpu_bo_create_kernel_at(adev, 
adev->mman.stolen_reserved_offset,
+                                                  
adev->mman.stolen_reserved_size,
+                                                  AMDGPU_GEM_DOMAIN_VRAM,
+                                                  
&adev->mman.stolen_reserved_memory,
+                                                  NULL);
+       else if (adev->mman.stolen_reserved_offset + 
adev->mman.stolen_reserved_size > memory_offset)
+               r = amdgpu_bo_create_kernel_at(adev, memory_offset,
+                                               adev->mman.stolen_reserved_offset 
+ adev->mman.stolen_reserved_size - memory_offset,
+                                                  AMDGPU_GEM_DOMAIN_VRAM,
+                                                  
&adev->mman.stolen_reserved_memory,
+                                                  NULL);
        if (r)
                return r;