accel/habanalabs: export dma-buf only if size/offset multiples of PAGE_SIZE

It is currently allowed for a user to export dma-buf with size and
offset that are not multiples of PAGE_SIZE.
The exported memory is mapped for the importer device, and there it will
be rounded to PAGE_SIZE, leading to actually exporting more than the
user intended to.
To make the user be aware of it, accept only size and offset which are
multiple of PAGE_SIZE.

Signed-off-by: Tomer Tayar <ttayar@habana.ai>
Reviewed-by: Oded Gabbay <ogabbay@kernel.org>
Signed-off-by: Oded Gabbay <ogabbay@kernel.org>

Author: Tomer Tayar

drivers/accel/habanalabs/common/memory.c

@@ -1877,16 +1877,16 @@ static int export_dmabuf(struct hl_ctx *ctx,
 
 static int validate_export_params_common(struct hl_device *hdev, u64 device_addr, u64 size)
 {
-	if (!IS_ALIGNED(device_addr, PAGE_SIZE)) {
+	if (!PAGE_ALIGNED(device_addr)) {
 		dev_dbg(hdev->dev,
-			"exported device memory address 0x%llx should be aligned to 0x%lx\n",
+			"exported device memory address 0x%llx should be aligned to PAGE_SIZE 0x%lx\n",
 			device_addr, PAGE_SIZE);
 		return -EINVAL;
 	}
 
-	if (size < PAGE_SIZE) {
+	if (!size || !PAGE_ALIGNED(size)) {
 		dev_dbg(hdev->dev,
-			"exported device memory size %llu should be equal to or greater than %lu\n",
+			"exported device memory size %llu should be a multiple of PAGE_SIZE %lu\n",
 			size, PAGE_SIZE);
 		return -EINVAL;
 	}
@@ -1937,6 +1937,13 @@ static int validate_export_params(struct hl_device *hdev, u64 device_addr, u64 s
 	if (rc)
 		return rc;
 
+	if (!PAGE_ALIGNED(offset)) {
+		dev_dbg(hdev->dev,
+			"exported device memory offset %llu should be a multiple of PAGE_SIZE %lu\n",
+			offset, PAGE_SIZE);
+		return -EINVAL;
+	}
+
 	if ((offset + size) > phys_pg_pack->total_size) {
 		dev_dbg(hdev->dev, "offset %#llx and size %#llx exceed total map size %#llx\n",
 				offset, size, phys_pg_pack->total_size);