3 files changed, 78 insertions, 21 deletions

diff --git a/drivers/gpu/drm/gud/gud_drv.c b/drivers/gpu/drm/gud/gud_drv.c
index 8518cde03f8f..d02f8e968aad 100644
--- a/drivers/gpu/drm/gud/gud_drv.c
+++ b/drivers/gpu/drm/gud/gud_drv.c
@@ -393,13 +393,40 @@ static const struct drm_driver gud_drm_driver = {
 	.minor			= 0,
 };
 
+static int gud_alloc_bulk_buffer(struct gud_device *gdrm)
+{
+	unsigned int i, num_pages;
+	struct page **pages;
+	void *ptr;
+	int ret;
+
+	gdrm->bulk_buf = vmalloc_32(gdrm->bulk_len);
+	if (!gdrm->bulk_buf)
+		return -ENOMEM;
+
+	num_pages = DIV_ROUND_UP(gdrm->bulk_len, PAGE_SIZE);
+	pages = kmalloc_array(num_pages, sizeof(struct page *), GFP_KERNEL);
+	if (!pages)
+		return -ENOMEM;
+
+	for (i = 0, ptr = gdrm->bulk_buf; i < num_pages; i++, ptr += PAGE_SIZE)
+		pages[i] = vmalloc_to_page(ptr);
+
+	ret = sg_alloc_table_from_pages(&gdrm->bulk_sgt, pages, num_pages,
+					0, gdrm->bulk_len, GFP_KERNEL);
+	kfree(pages);
+
+	return ret;
+}
+
 static void gud_free_buffers_and_mutex(void *data)
 {
 	struct gud_device *gdrm = data;
 
 	vfree(gdrm->compress_buf);
 	gdrm->compress_buf = NULL;
-	kfree(gdrm->bulk_buf);
+	sg_free_table(&gdrm->bulk_sgt);
+	vfree(gdrm->bulk_buf);
 	gdrm->bulk_buf = NULL;
 	mutex_destroy(&gdrm->ctrl_lock);
 }
@@ -536,24 +563,17 @@ static int gud_probe(struct usb_interface *intf, const struct usb_device_id *id)
 
 	if (desc.max_buffer_size)
 		max_buffer_size = le32_to_cpu(desc.max_buffer_size);
-retry:
-	/*
-	 * Use plain kmalloc here since devm_kmalloc() places struct devres at the beginning
-	 * of the buffer it allocates. This wastes a lot of memory when allocating big buffers.
-	 * Asking for 2M would actually allocate 4M. This would also prevent getting the biggest
-	 * possible buffer potentially leading to split transfers.
-	 */
-	gdrm->bulk_buf = kmalloc(max_buffer_size, GFP_KERNEL | __GFP_NOWARN);
-	if (!gdrm->bulk_buf) {
-		max_buffer_size = roundup_pow_of_two(max_buffer_size) / 2;
-		if (max_buffer_size < SZ_512K)
-			return -ENOMEM;
-		goto retry;
-	}
+	/* Prevent a misbehaving device from allocating loads of RAM. 4096x4096@XRGB8888 = 64 MB */
+	if (max_buffer_size > SZ_64M)
+		max_buffer_size = SZ_64M;
 
 	gdrm->bulk_pipe = usb_sndbulkpipe(interface_to_usbdev(intf), usb_endpoint_num(bulk_out));
 	gdrm->bulk_len = max_buffer_size;
 
+	ret = gud_alloc_bulk_buffer(gdrm);
+	if (ret)
+		return ret;
+
 	if (gdrm->compression & GUD_COMPRESSION_LZ4) {
 		gdrm->lz4_comp_mem = devm_kmalloc(dev, LZ4_MEM_COMPRESS, GFP_KERNEL);
 		if (!gdrm->lz4_comp_mem)
diff --git a/drivers/gpu/drm/gud/gud_internal.h b/drivers/gpu/drm/gud/gud_internal.h
index b65105585578..2a388e27d5d7 100644
--- a/drivers/gpu/drm/gud/gud_internal.h
+++ b/drivers/gpu/drm/gud/gud_internal.h
@@ -5,6 +5,7 @@
 
 #include <linux/list.h>
 #include <linux/mutex.h>
+#include <linux/scatterlist.h>
 #include <linux/usb.h>
 #include <linux/workqueue.h>
 #include <uapi/drm/drm_fourcc.h>
@@ -26,6 +27,7 @@ struct gud_device {
 	unsigned int bulk_pipe;
 	void *bulk_buf;
 	size_t bulk_len;
+	struct sg_table bulk_sgt;
 
 	u8 compression;
 	void *lz4_comp_mem;
diff --git a/drivers/gpu/drm/gud/gud_pipe.c b/drivers/gpu/drm/gud/gud_pipe.c
index 2f83ab6b8e61..e0fb6cc969a3 100644
--- a/drivers/gpu/drm/gud/gud_pipe.c
+++ b/drivers/gpu/drm/gud/gud_pipe.c
@@ -220,13 +220,51 @@ vunmap:
 	return ret;
 }
 
+struct gud_usb_bulk_context {
+	struct timer_list timer;
+	struct usb_sg_request sgr;
+};
+
+static void gud_usb_bulk_timeout(struct timer_list *t)
+{
+	struct gud_usb_bulk_context *ctx = from_timer(ctx, t, timer);
+
+	usb_sg_cancel(&ctx->sgr);
+}
+
+static int gud_usb_bulk(struct gud_device *gdrm, size_t len)
+{
+	struct gud_usb_bulk_context ctx;
+	int ret;
+
+	ret = usb_sg_init(&ctx.sgr, gud_to_usb_device(gdrm), gdrm->bulk_pipe, 0,
+			  gdrm->bulk_sgt.sgl, gdrm->bulk_sgt.nents, len, GFP_KERNEL);
+	if (ret)
+		return ret;
+
+	timer_setup_on_stack(&ctx.timer, gud_usb_bulk_timeout, 0);
+	mod_timer(&ctx.timer, jiffies + msecs_to_jiffies(3000));
+
+	usb_sg_wait(&ctx.sgr);
+
+	if (!del_timer_sync(&ctx.timer))
+		ret = -ETIMEDOUT;
+	else if (ctx.sgr.status < 0)
+		ret = ctx.sgr.status;
+	else if (ctx.sgr.bytes != len)
+		ret = -EIO;
+
+	destroy_timer_on_stack(&ctx.timer);
+
+	return ret;
+}
+
 static int gud_flush_rect(struct gud_device *gdrm, struct drm_framebuffer *fb,
 			  const struct drm_format_info *format, struct drm_rect *rect)
 {
-	struct usb_device *usb = gud_to_usb_device(gdrm);
 	struct gud_set_buffer_req req;
-	int ret, actual_length;
 	size_t len, trlen;
+	int ret;
 
 	drm_dbg(&gdrm->drm, "Flushing [FB:%d] " DRM_RECT_FMT "\n", fb->base.id, DRM_RECT_ARG(rect));
 
@@ -255,10 +293,7 @@ static int gud_flush_rect(struct gud_device *gdrm, struct drm_framebuffer *fb,
 			return ret;
 	}
 
-	ret = usb_bulk_msg(usb, gdrm->bulk_pipe, gdrm->bulk_buf, trlen,
-			   &actual_length, msecs_to_jiffies(3000));
-	if (!ret && trlen != actual_length)
-		ret = -EIO;
+	ret = gud_usb_bulk(gdrm, trlen);
 	if (ret)
 		gdrm->stats_num_errors++;