drm/xe: Add sa/guc_buf_cache sync interface

In upcoming changes the cached buffers are going to be used to read data
produced by the GuC. Add a counterpart to flush, which synchronizes the
CPU-side of suballocation with the GPU data and propagate the interface
to GuC Buffer Cache.

Reviewed-by: Michal Wajdeczko <michal.wajdeczko@intel.com>
Link: https://patch.msgid.link/20251112132220.516975-11-michal.winiarski@intel.com
Signed-off-by: Michał Winiarski <michal.winiarski@intel.com>

Author: mwiniars

drivers/gpu/drm/xe/xe_guc_buf.c

@@ -115,6 +115,19 @@ void xe_guc_buf_release(const struct xe_guc_buf buf)
 		xe_sa_bo_free(buf.sa, NULL);
 }
 
+/**
+ * xe_guc_buf_sync_read() - Copy the data from the GPU memory to the sub-allocation.
+ * @buf: the &xe_guc_buf to sync
+ *
+ * Return: a CPU pointer of the sub-allocation.
+ */
+void *xe_guc_buf_sync_read(const struct xe_guc_buf buf)
+{
+	xe_sa_bo_sync_read(buf.sa);
+
+	return xe_sa_bo_cpu_addr(buf.sa);
+}
+
 /**
  * xe_guc_buf_flush() - Copy the data from the sub-allocation to the GPU memory.
  * @buf: the &xe_guc_buf to flush

drivers/gpu/drm/xe/xe_guc_buf.h

@@ -30,6 +30,7 @@ static inline bool xe_guc_buf_is_valid(const struct xe_guc_buf buf)
 }
 
 void *xe_guc_buf_cpu_ptr(const struct xe_guc_buf buf);
+void *xe_guc_buf_sync_read(const struct xe_guc_buf buf);
 u64 xe_guc_buf_flush(const struct xe_guc_buf buf);
 u64 xe_guc_buf_gpu_addr(const struct xe_guc_buf buf);
 u64 xe_guc_cache_gpu_addr_from_ptr(struct xe_guc_buf_cache *cache, const void *ptr, u32 size);

drivers/gpu/drm/xe/xe_sa.c

@@ -110,6 +110,10 @@ struct drm_suballoc *__xe_sa_bo_new(struct xe_sa_manager *sa_manager, u32 size,
 	return drm_suballoc_new(&sa_manager->base, size, gfp, true, 0);
 }
 
+/**
+ * xe_sa_bo_flush_write() - Copy the data from the sub-allocation to the GPU memory.
+ * @sa_bo: the &drm_suballoc to flush
+ */
 void xe_sa_bo_flush_write(struct drm_suballoc *sa_bo)
 {
 	struct xe_sa_manager *sa_manager = to_xe_sa_manager(sa_bo->manager);
@@ -123,6 +127,23 @@ void xe_sa_bo_flush_write(struct drm_suballoc *sa_bo)
 			 drm_suballoc_size(sa_bo));
 }
 
+/**
+ * xe_sa_bo_sync_read() - Copy the data from GPU memory to the sub-allocation.
+ * @sa_bo: the &drm_suballoc to sync
+ */
+void xe_sa_bo_sync_read(struct drm_suballoc *sa_bo)
+{
+	struct xe_sa_manager *sa_manager = to_xe_sa_manager(sa_bo->manager);
+	struct xe_device *xe = tile_to_xe(sa_manager->bo->tile);
+
+	if (!sa_manager->bo->vmap.is_iomem)
+		return;
+
+	xe_map_memcpy_from(xe, xe_sa_bo_cpu_addr(sa_bo), &sa_manager->bo->vmap,
+			   drm_suballoc_soffset(sa_bo),
+			   drm_suballoc_size(sa_bo));
+}
+
 void xe_sa_bo_free(struct drm_suballoc *sa_bo,
 		   struct dma_fence *fence)
 {

drivers/gpu/drm/xe/xe_sa.h

@@ -37,6 +37,7 @@ static inline struct drm_suballoc *xe_sa_bo_new(struct xe_sa_manager *sa_manager
 }
 
 void xe_sa_bo_flush_write(struct drm_suballoc *sa_bo);
+void xe_sa_bo_sync_read(struct drm_suballoc *sa_bo);
 void xe_sa_bo_free(struct drm_suballoc *sa_bo, struct dma_fence *fence);
 
 static inline struct xe_sa_manager *