[PATCH v6] drm/amdgpu: Fix AMDGPU_GTT_MAX_TRANSFER_SIZE for non-4K page size

[Donet Tom <donettom@linux.ibm.com>]

AMDGPU_GTT_MAX_TRANSFER_SIZE represented the maximum number of
system-page-sized pages that could be transferred in a single
operation. The effective maximum transfer size was intended to be
one PMD-sized mapping.

In the existing code, AMDGPU_GTT_MAX_TRANSFER_SIZE was hard-coded
to 512 pages. This corresponded to 2 MB on 4 KB page-size systems,
matching the PMD size. However, on systems with a non-4 KB page
size, this value no longer matched the PMD size.

This patch changed the calculation of AMDGPU_GTT_MAX_TRANSFER_SIZE
to derive it from PMD_SHIFT and PAGE_SHIFT, ensuring that the
maximum transfer size remained PMD-sized across all system page
sizes.

Additionally, in some places, AMDGPU_GTT_MAX_TRANSFER_SIZE was
implicitly assumed to be based on 4 KB pages. This resulted in
incorrect address offset calculations. This patch updated the
address calculations to correctly handle non-4 KB system page
sizes as well.

amdgpu_ttm_map_buffer() can create both GTT GART entries and
VRAM GART entries. For GTT mappings, amdgpu_gart_map() takes
system page–sized PFNs, and the mappings are created correctly.

However, for VRAM GART mappings, amdgpu_gart_map_vram_range() expects
GPU page–sized PFNs, but CPU page–sized PFNs were being passed,
resulting in incorrect mappings.

This patch updates the code to pass GPU page–sized PFNs to
amdgpu_gart_map_vram_range(), ensuring that VRAM GART mappings are
created correctly.

Signed-off-by: Donet Tom <donettom@linux.ibm.com>
---

This patch is necessary, as it ensures the correct window is used
while mapping the buffer. Without this fix, amdgpu_gart_map_vram_range()
does not create all the required mappings when the page size is not 4K.
Since this is also an important fix for enabling non-4K page size support,
I would be grateful if you could take a look and share your feedback.

---
 drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c | 8 +++++---
 drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.h | 2 +-
 drivers/gpu/drm/amd/amdgpu/vce_v1_0.c   | 3 ++-
 3 files changed, 8 insertions(+), 5 deletions(-)

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
index 0ccb31788b20..f9f534119cbe 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
@@ -204,7 +204,7 @@ static int amdgpu_ttm_map_buffer(struct amdgpu_ttm_buffer_entity *entity,
 	int r;
 
 	BUG_ON(adev->mman.buffer_funcs->copy_max_bytes <
-	       AMDGPU_GTT_MAX_TRANSFER_SIZE * 8);
+	       AMDGPU_GTT_MAX_TRANSFER_SIZE * AMDGPU_GPU_PAGES_IN_CPU_PAGE * 8);
 
 	if (WARN_ON(mem->mem_type == AMDGPU_PL_PREEMPT))
 		return -EINVAL;
@@ -230,7 +230,7 @@ static int amdgpu_ttm_map_buffer(struct amdgpu_ttm_buffer_entity *entity,
 
 	*addr = adev->gmc.gart_start;
 	*addr += (u64)window * AMDGPU_GTT_MAX_TRANSFER_SIZE *
-		AMDGPU_GPU_PAGE_SIZE;
+		AMDGPU_GPU_PAGES_IN_CPU_PAGE * AMDGPU_GPU_PAGE_SIZE;
 	*addr += offset;
 
 	num_dw = ALIGN(adev->mman.buffer_funcs->copy_num_dw, 8);
@@ -248,7 +248,8 @@ static int amdgpu_ttm_map_buffer(struct amdgpu_ttm_buffer_entity *entity,
 	src_addr += job->ibs[0].gpu_addr;
 
 	dst_addr = amdgpu_bo_gpu_offset(adev->gart.bo);
-	dst_addr += window * AMDGPU_GTT_MAX_TRANSFER_SIZE * 8;
+	dst_addr += window * AMDGPU_GTT_MAX_TRANSFER_SIZE *
+		AMDGPU_GPU_PAGES_IN_CPU_PAGE * 8;
 	amdgpu_emit_copy_buffer(adev, &job->ibs[0], src_addr,
 				dst_addr, num_bytes, 0);
 
@@ -266,6 +267,7 @@ static int amdgpu_ttm_map_buffer(struct amdgpu_ttm_buffer_entity *entity,
 	} else {
 		u64 pa = mm_cur->start + adev->vm_manager.vram_base_offset;
 
+		num_pages *= AMDGPU_GPU_PAGES_IN_CPU_PAGE;
 		amdgpu_gart_map_vram_range(adev, pa, 0, num_pages, flags, cpu_addr);
 	}
 
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.h b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.h
index 143201ecea3f..15aff225af1d 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.h
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.h
@@ -38,7 +38,7 @@
 #define AMDGPU_PL_MMIO_REMAP	(TTM_PL_PRIV + 5)
 #define __AMDGPU_PL_NUM	(TTM_PL_PRIV + 6)
 
-#define AMDGPU_GTT_MAX_TRANSFER_SIZE	512
+#define AMDGPU_GTT_MAX_TRANSFER_SIZE	(1 << (PMD_SHIFT - PAGE_SHIFT))
 #define AMDGPU_GTT_NUM_TRANSFER_WINDOWS	2
 
 extern const struct attribute_group amdgpu_vram_mgr_attr_group;
diff --git a/drivers/gpu/drm/amd/amdgpu/vce_v1_0.c b/drivers/gpu/drm/amd/amdgpu/vce_v1_0.c
index 9ae424618556..b2d4114c258c 100644
--- a/drivers/gpu/drm/amd/amdgpu/vce_v1_0.c
+++ b/drivers/gpu/drm/amd/amdgpu/vce_v1_0.c
@@ -48,7 +48,8 @@
 #define VCE_STATUS_VCPU_REPORT_FW_LOADED_MASK	0x02
 
 #define VCE_V1_0_GART_PAGE_START \
-	(AMDGPU_GTT_MAX_TRANSFER_SIZE * AMDGPU_GTT_NUM_TRANSFER_WINDOWS)
+	(AMDGPU_GTT_MAX_TRANSFER_SIZE * AMDGPU_GPU_PAGES_IN_CPU_PAGE * \
+	 AMDGPU_GTT_NUM_TRANSFER_WINDOWS)
 #define VCE_V1_0_GART_ADDR_START \
 	(VCE_V1_0_GART_PAGE_START * AMDGPU_GPU_PAGE_SIZE)
 
-- 
2.52.0