habanalabs: do MMU prefetch as deferred work

When user requests to prefetch the MMU translations, the driver will
not block the user until prefetch is done.
Instead, the prefetch work will be delegated to a WQ which will do it
in the background.
This way, the prefetch may progress without blocking the user at all.

Signed-off-by: Ohad Sharabi <osharabi@habana.ai>
Reviewed-by: Oded Gabbay <ogabbay@kernel.org>
Signed-off-by: Oded Gabbay <ogabbay@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 19 insertions, 12 deletions

diff --git a/drivers/misc/habanalabs/common/memory.c b/drivers/misc/habanalabs/common/memory.c
index ecf3c094242a..087a55654a4d 100644
--- a/drivers/misc/habanalabs/common/memory.c
+++ b/drivers/misc/habanalabs/common/memory.c
@@ -1102,21 +1102,24 @@ static int get_paddr_from_handle(struct hl_ctx *ctx, struct hl_mem_in *args,
  *   map a device virtual block to this pages and return the start address of
  *   this block.
  */
-static int map_device_va(struct hl_ctx *ctx, struct hl_mem_in *args,
-		u64 *device_addr)
+static int map_device_va(struct hl_ctx *ctx, struct hl_mem_in *args, u64 *device_addr)
 {
-	struct hl_device *hdev = ctx->hdev;
-	struct hl_vm *vm = &hdev->vm;
 	struct hl_vm_phys_pg_pack *phys_pg_pack;
+	enum hl_va_range_type va_range_type = 0;
+	struct hl_device *hdev = ctx->hdev;
 	struct hl_userptr *userptr = NULL;
+	u32 handle = 0, va_block_align;
 	struct hl_vm_hash_node *hnode;
+	struct hl_vm *vm = &hdev->vm;
 	struct hl_va_range *va_range;
-	enum vm_type *vm_type;
+	bool is_userptr, do_prefetch;
 	u64 ret_vaddr, hint_addr;
-	u32 handle = 0, va_block_align;
+	enum vm_type *vm_type;
 	int rc;
-	bool is_userptr = args->flags & HL_MEM_USERPTR;
-	enum hl_va_range_type va_range_type = 0;
+
+	/* set map flags */
+	is_userptr = args->flags & HL_MEM_USERPTR;
+	do_prefetch = hdev->supports_mmu_prefetch && (args->flags & HL_MEM_PREFETCH);
 
 	/* Assume failure */
 	*device_addr = 0;
@@ -1250,15 +1253,19 @@ static int map_device_va(struct hl_ctx *ctx, struct hl_mem_in *args,
 	if (rc)
 		goto map_err;
 
-	if (args->flags & HL_MEM_PREFETCH) {
-		rc = hl_mmu_prefetch_cache_range(hdev, *vm_type, ctx->asid, ret_vaddr,
+	mutex_unlock(&ctx->mmu_lock);
+
+	/*
+	 * prefetch is done upon user's request. it is performed in WQ as and so can
+	 * be outside the MMU lock. the operation itself is already protected by the mmu lock
+	 */
+	if (do_prefetch) {
+		rc = hl_mmu_prefetch_cache_range(ctx, *vm_type, ctx->asid, ret_vaddr,
 							phys_pg_pack->total_size);
 		if (rc)
 			goto map_err;
 	}
 
-	mutex_unlock(&ctx->mmu_lock);
-
 	ret_vaddr += phys_pg_pack->offset;
 
 	hnode->ptr = vm_type;