[PATCH v3 21/30] drm/xe: Add drm_pagemap ops to SVM

[Matthew Brost]

From: Thomas Hellström <thomas.hellstrom at 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.brost at intel.com>
Signed-off-by: Thomas Hellström <thomas.hellstrom at linux.intel.com>
Reviewed-by: Matthew Brost <matthew.brost at intel.com>
---
 drivers/gpu/drm/xe/xe_device_types.h |  7 +++++++
 drivers/gpu/drm/xe/xe_svm.c          | 30 ++++++++++++++++++++++++++++
 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 b949a960cebb..b76d08df13ef 100644
--- a/drivers/gpu/drm/xe/xe_device_types.h
+++ b/drivers/gpu/drm/xe/xe_device_types.h
@@ -10,8 +10,10 @@
 
 #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"
 #include "xe_heci_gsc.h"
 #include "xe_lmtt_types.h"
@@ -104,6 +106,11 @@ 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 2860e54bb035..faeacf0ccdaa 100644
--- a/drivers/gpu/drm/xe/xe_svm.c
+++ b/drivers/gpu/drm/xe/xe_svm.c
@@ -449,6 +449,32 @@ bool xe_svm_has_mapping(struct xe_vm *vm, u64 start, u64 end)
 }
 
 #if IS_ENABLED(CONFIG_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,
+};
+
 /**
  * xe_devm_add: Remap and provide memmap backing for device memory
  * @tile: tile that the memory region belongs to
@@ -481,6 +507,10 @@ 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);
-- 
2.34.1