Re: [PATCH v4 23/33] drm/xe: Add drm_pagemap ops to SVM

[Matthew Auld]

On 29/01/2025 19:52, Matthew Brost wrote:

From: Thomas Hellström <thomas.hellst...@linux.intel.com>

Add support for mapping device pages to Xe SVM by attaching drm_pagemap
to a memory region, which is then linked to a GPU SVM devmem allocation.
This enables GPU SVM to derive the device page address.

v3:
  - Better commit message (Thomas)
  - New drm_pagemap.h location

Signed-off-by: Matthew Brost <matthew.br...@intel.com>
Signed-off-by: Thomas Hellström <thomas.hellst...@linux.intel.com>
Reviewed-by: Matthew Brost <matthew.br...@intel.com>
---
  drivers/gpu/drm/xe/xe_device_types.h |  6 ++++++
  drivers/gpu/drm/xe/xe_svm.c          | 31 ++++++++++++++++++++++++++++
  2 files changed, 37 insertions(+)

diff --git a/drivers/gpu/drm/xe/xe_device_types.h 
b/drivers/gpu/drm/xe/xe_device_types.h
index da5bf145324b..eb3702db5c17 100644
--- a/drivers/gpu/drm/xe/xe_device_types.h
+++ b/drivers/gpu/drm/xe/xe_device_types.h
@@ -10,6 +10,7 @@

#include <drm/drm_device.h>

  #include <drm/drm_file.h>
+#include <drm/drm_pagemap.h>
  #include <drm/ttm/ttm_device.h>

#include "xe_devcoredump_types.h"

@@ -106,6 +107,11 @@ struct xe_mem_region {
        void __iomem *mapping;
        /** @pagemap: Used to remap device memory as ZONE_DEVICE */
        struct dev_pagemap pagemap;
+       /**
+        * @dpagemap: The struct drm_pagemap of the ZONE_DEVICE memory
+        * pages of this tile.
+        */
+       struct drm_pagemap dpagemap;
        /**
         * @hpa_base: base host physical address
         *
diff --git a/drivers/gpu/drm/xe/xe_svm.c b/drivers/gpu/drm/xe/xe_svm.c
index 985ac20c5b07..869a155fc9f7 100644
--- a/drivers/gpu/drm/xe/xe_svm.c
+++ b/drivers/gpu/drm/xe/xe_svm.c
@@ -450,6 +450,33 @@ bool xe_svm_has_mapping(struct xe_vm *vm, u64 start, u64 
end)
  }

#if IS_ENABLED(CONFIG_DRM_XE_DEVMEM_MIRROR)

+static struct drm_pagemap_dma_addr
+xe_drm_pagemap_map_dma(struct drm_pagemap *dpagemap,
+                      struct device *dev,
+                      struct page *page,
+                      unsigned int order,
+                      enum dma_data_direction dir)
+{
+       struct device *pgmap_dev = dpagemap->dev;
+       enum drm_interconnect_protocol prot;
+       dma_addr_t addr;
+
+       if (pgmap_dev == dev) {
+               addr = xe_mem_region_page_to_dpa(page_to_mr(page), page);
+               prot = XE_INTERCONNECT_VRAM;
+       } else {
+               addr = DMA_MAPPING_ERROR;
+               prot = 0;
+       }
+
+       return drm_pagemap_dma_addr_encode(addr, prot, order, dir);
+}
+
+static const struct drm_pagemap_ops xe_drm_pagemap_ops = {
+       .map_dma = xe_drm_pagemap_map_dma,
+};
+
+>>>>>>> 133db8ade5f0 (drm/xe: Add drm_pagemap ops to SVM)

Some leftover rebase damage here?

  /**
   * xe_devm_add: Remap and provide memmap backing for device memory
   * @tile: tile that the memory region belongs to
@@ -482,6 +509,10 @@ int xe_devm_add(struct xe_tile *tile, struct xe_mem_region 
*mr)
        mr->pagemap.ops = drm_gpusvm_pagemap_ops_get();
        mr->pagemap.owner = xe_svm_devm_owner(xe);
        addr = devm_memremap_pages(dev, &mr->pagemap);
+
+       mr->dpagemap.dev = dev;
+       mr->dpagemap.ops = &xe_drm_pagemap_ops;
+
        if (IS_ERR(addr)) {
                devm_release_mem_region(dev, res->start, resource_size(res));
                ret = PTR_ERR(addr);