From: Michal Wajdeczko <michal.wajdeczko@intel.com>
Date: Mon, 22 Jun 2026 13:23:41 +0000 (+0200)
Subject: drm/xe/mmio: Check MMIO BAR size when initializing tiles
X-Git-Url: http://git.hungrycats.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=699ca9d4ec71e74c40e394bfa7616b56c82279fa;p=linux

drm/xe/mmio: Check MMIO BAR size when initializing tiles

We initialized all remote tiles' xe_mmio structures with a new size
of 4MiB and offsets of 16MiB without sanity checks to see if mapped
GTTMMADR_BAR was actually at least that size.

Signed-off-by: Michal Wajdeczko <michal.wajdeczko@intel.com>
Reviewed-by: Matthew Auld <matthew.auld@intel.com>
Link: https://patch.msgid.link/20260622132342.19600-6-michal.wajdeczko@intel.com
---

diff --git a/drivers/gpu/drm/xe/xe_mmio.c b/drivers/gpu/drm/xe/xe_mmio.c
index 58226cd8b3993..41e6b753634fa 100644
--- a/drivers/gpu/drm/xe/xe_mmio.c
+++ b/drivers/gpu/drm/xe/xe_mmio.c
@@ -48,21 +48,35 @@ static void mmio_multi_tile_setup(struct xe_device *xe, size_t tile_mmio_size)
 	struct xe_tile *tile;
 	u8 id;
 
-	/*
-	 * Nothing to be done as tile 0 has already been setup earlier with the
-	 * entire BAR mapped - see xe_mmio_probe_early()
-	 */
-	if (xe->info.tile_count == 1)
-		return;
-
 	for_each_remote_tile(tile, xe, id)
 		xe_mmio_init(&tile->mmio, tile, xe->mmio.regs + id * tile_mmio_size, SZ_4M);
 }
 
+/**
+ * xe_mmio_probe_tiles() - Initialize all tiles' MMIO
+ * @xe: the &xe_device
+ *
+ * Initialize the remaining tiles' MMIO instances.
+ *
+ * Return: 0 on success or a negative error code on failure.
+ */
 int xe_mmio_probe_tiles(struct xe_device *xe)
 {
 	size_t tile_mmio_size = SZ_16M;
 
+	/*
+	 * Nothing to be done as tile 0 has already been setup earlier with the
+	 * entire BAR mapped - see xe_mmio_probe_early()
+	 */
+	if (xe->info.tile_count == 1)
+		return 0;
+
+	if (xe->mmio.size < xe->info.tile_count * tile_mmio_size) {
+		xe_err(xe, "GTTMMADR_BAR is too small for %d tiles: %zu\n",
+		       xe->info.tile_count, xe->mmio.size);
+		return -EIO;
+	}
+
 	mmio_multi_tile_setup(xe, tile_mmio_size);
 	return 0;
 }