habanalabs: allow user to set allocation page size

In future ASICs the MMU will be able to work with multiple page sizes,
thus a new flag is added to allow the user to set the requested page
size.

This flag is added since the whole DRAM is allocated for the user and
the user also should be familiar with the memory usage use case.

As such, the user may choose to "over allocate" memory in favor of
performance (for instance- large page allocations covers more memory
in less TLB entries).

For example: say available page sizes are of 1MB and 32MB. If user
wants to allocate 40MB the user can either set page size to 1MB and
allocate the exact amount of memory (but will result in 40 TLB entries)
or the user can use 32MB pages, "waste" 8MB of physical memory but
occupy only 2 TLB entries.

Note that this feature will be available only to ASIC that supports
multiple DRAM page sizes.

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

1 files changed, 30 insertions, 1 deletions

diff --git a/drivers/misc/habanalabs/common/memory.c b/drivers/misc/habanalabs/common/memory.c
index 7bd4cae87a54..385bf3448c73 100644
--- a/drivers/misc/habanalabs/common/memory.c
+++ b/drivers/misc/habanalabs/common/memory.c
@@ -24,6 +24,31 @@ MODULE_IMPORT_NS(DMA_BUF);
 static int allocate_timestamps_buffers(struct hl_fpriv *hpriv,
 			struct hl_mem_in *args, u64 *handle);
 
+static int set_alloc_page_size(struct hl_device *hdev, struct hl_mem_in *args, u32 *page_size)
+{
+	struct asic_fixed_properties *prop = &hdev->asic_prop;
+	u32 psize;
+
+	/*
+	 * for ASIC that supports setting the allocation page size by user we will address
+	 * user's choice only if it is not 0 (as 0 means taking the default page size)
+	 */
+	if (prop->supports_user_set_page_size && args->alloc.page_size) {
+		psize = args->alloc.page_size;
+
+		if (!hdev->asic_funcs->is_valid_dram_page_size(psize)) {
+			dev_err(hdev->dev, "user page size (%#x) is not valid\n", psize);
+			return -EINVAL;
+		}
+	} else {
+		psize = hdev->asic_prop.dram_page_size;
+	}
+
+	*page_size = psize;
+
+	return 0;
+}
+
 /*
  * The va ranges in context object contain a list with the available chunks of
  * device virtual memory.
@@ -69,7 +94,11 @@ static int alloc_device_memory(struct hl_ctx *ctx, struct hl_mem_in *args,
 	bool contiguous;
 
 	num_curr_pgs = 0;
-	page_size = hdev->asic_prop.dram_page_size;
+
+	rc = set_alloc_page_size(hdev, args, &page_size);
+	if (rc)
+		return rc;
+
 	num_pgs = DIV_ROUND_UP_ULL(args->alloc.mem_size, page_size);
 	total_size = num_pgs * page_size;