drm/vmwgfx: Split GMR2_REMAP commands if they are to large

This fixes the piglit test texturing/max-texture-size
causing the VM to die due to a too large SVGA command.
Signed-off-by: Jakob Bornecrantz <jakob@vmware.com>
Reviewed-by: Biran Paul <brianp@vmware.com>
Reviewed-by: Zack Rusin <zackr@vmware.com>
Cc: stable@vger.kernel.org
Signed-off-by: Dave Airlie <airlied@gmail.com>

drivers/gpu/drm/vmwgfx/vmwgfx_gmr.c

@@ -29,7 +29,9 @@
 #include <drm/drmP.h>
 #include <drm/ttm/ttm_bo_driver.h>
 
-#define VMW_PPN_SIZE sizeof(unsigned long)
+#define VMW_PPN_SIZE (sizeof(unsigned long))
+/* A future safe maximum remap size. */
+#define VMW_PPN_PER_REMAP ((31 * 1024) / VMW_PPN_SIZE)
 
 static int vmw_gmr2_bind(struct vmw_private *dev_priv,
 			 struct page *pages[],
@@ -38,34 +40,46 @@ static int vmw_gmr2_bind(struct vmw_private *dev_priv,
 {
 	SVGAFifoCmdDefineGMR2 define_cmd;
 	SVGAFifoCmdRemapGMR2 remap_cmd;
-	uint32_t define_size = sizeof(define_cmd) + 4;
-	uint32_t remap_size = VMW_PPN_SIZE * num_pages + sizeof(remap_cmd) + 4;
 	uint32_t *cmd;
 	uint32_t *cmd_orig;
+	uint32_t define_size = sizeof(define_cmd) + sizeof(*cmd);
+	uint32_t remap_num = num_pages / VMW_PPN_PER_REMAP + ((num_pages % VMW_PPN_PER_REMAP) > 0);
+	uint32_t remap_size = VMW_PPN_SIZE * num_pages + (sizeof(remap_cmd) + sizeof(*cmd)) * remap_num;
+	uint32_t remap_pos = 0;
+	uint32_t cmd_size = define_size + remap_size;
 	uint32_t i;
 
-	cmd_orig = cmd = vmw_fifo_reserve(dev_priv, define_size + remap_size);
+	cmd_orig = cmd = vmw_fifo_reserve(dev_priv, cmd_size);
 	if (unlikely(cmd == NULL))
 		return -ENOMEM;
 
 	define_cmd.gmrId = gmr_id;
 	define_cmd.numPages = num_pages;
 
+	*cmd++ = SVGA_CMD_DEFINE_GMR2;
+	memcpy(cmd, &define_cmd, sizeof(define_cmd));
+	cmd += sizeof(define_cmd) / sizeof(*cmd);
+
+	/*
+	 * Need to split the command if there are too many
+	 * pages that goes into the gmr.
+	 */
+
 	remap_cmd.gmrId = gmr_id;
 	remap_cmd.flags = (VMW_PPN_SIZE > sizeof(*cmd)) ?
 		SVGA_REMAP_GMR2_PPN64 : SVGA_REMAP_GMR2_PPN32;
-	remap_cmd.offsetPages = 0;
-	remap_cmd.numPages = num_pages;
 
-	*cmd++ = SVGA_CMD_DEFINE_GMR2;
-	memcpy(cmd, &define_cmd, sizeof(define_cmd));
-	cmd += sizeof(define_cmd) / sizeof(uint32);
+	while (num_pages > 0) {
+		unsigned long nr = min(num_pages, (unsigned long)VMW_PPN_PER_REMAP);
+
+		remap_cmd.offsetPages = remap_pos;
+		remap_cmd.numPages = nr;
 
 		*cmd++ = SVGA_CMD_REMAP_GMR2;
 		memcpy(cmd, &remap_cmd, sizeof(remap_cmd));
-	cmd += sizeof(remap_cmd) / sizeof(uint32);
+		cmd += sizeof(remap_cmd) / sizeof(*cmd);
 
-	for (i = 0; i < num_pages; ++i) {
+		for (i = 0; i < nr; ++i) {
 			if (VMW_PPN_SIZE <= 4)
 				*cmd = page_to_pfn(*pages++);
 			else
@@ -74,7 +88,13 @@ static int vmw_gmr2_bind(struct vmw_private *dev_priv,
 			cmd += VMW_PPN_SIZE / sizeof(*cmd);
 		}
 
-	vmw_fifo_commit(dev_priv, define_size + remap_size);
+		num_pages -= nr;
+		remap_pos += nr;
+	}
+
+	BUG_ON(cmd != cmd_orig + cmd_size / sizeof(*cmd));
+
+	vmw_fifo_commit(dev_priv, cmd_size);
 
 	return 0;
 }