diff --git a/drivers/gpu/drm/xe/xe_device_types.h b/drivers/gpu/drm/xe/xe_device_types.h
index 00b1db28a4b4..8d99450f0bf4 100644
--- a/drivers/gpu/drm/xe/xe_device_types.h
+++ b/drivers/gpu/drm/xe/xe_device_types.h
@@ -115,9 +115,19 @@ struct xe_device {
 	struct {
 		/** @vram: VRAM info for device */
 		struct {
-			/** @io_start: start address of VRAM */
+			/** @io_start: IO start address of VRAM */
 			resource_size_t io_start;
-			/** @size: size of VRAM */
+			/**
+			 * @io_size: IO size of VRAM.
+			 *
+			 * This represents how much of VRAM we can access via
+			 * the CPU through the VRAM BAR. This can be smaller
+			 * than @size, in which case only part of VRAM is CPU
+			 * accessible (typically the first 256M). This
+			 * configuration is known as small-bar.
+			 */
+			resource_size_t io_size;
+			/** @size: Total size of VRAM */
 			resource_size_t size;
 			/** @mapping: pointer to VRAM mappable space */
 			void *__iomem mapping;
diff --git a/drivers/gpu/drm/xe/xe_gt_types.h b/drivers/gpu/drm/xe/xe_gt_types.h
index 74b4e6776bf1..8f29aba455e0 100644
--- a/drivers/gpu/drm/xe/xe_gt_types.h
+++ b/drivers/gpu/drm/xe/xe_gt_types.h
@@ -143,9 +143,19 @@ struct xe_gt {
 		 * (virtual split), can be subset of global device VRAM
 		 */
 		struct {
-			/** @io_start: start address of VRAM */
+			/** @io_start: IO start address of this VRAM instance */
 			resource_size_t io_start;
-			/** @size: size of VRAM */
+			/**
+			 * @io_size: IO size of this VRAM instance
+			 *
+			 * This represents how much of this VRAM we can access
+			 * via the CPU through the VRAM BAR. This can be smaller
+			 * than @size, in which case only part of VRAM is CPU
+			 * accessible (typically the first 256M). This
+			 * configuration is known as small-bar.
+			 */
+			resource_size_t io_size;
+			/** @size: size of VRAM. */
 			resource_size_t size;
 			/** @mapping: pointer to VRAM mappable space */
 			void *__iomem mapping;
diff --git a/drivers/gpu/drm/xe/xe_mmio.c b/drivers/gpu/drm/xe/xe_mmio.c
index e5bd4609aaee..5cacaa05759a 100644
--- a/drivers/gpu/drm/xe/xe_mmio.c
+++ b/drivers/gpu/drm/xe/xe_mmio.c
@@ -182,7 +182,6 @@ int xe_mmio_probe_vram(struct xe_device *xe)
 	u8 id;
 	u64 vram_size;
 	u64 original_size;
-	u64 current_size;
 	u64 usable_size;
 	int resize_result, err;
 
@@ -190,11 +189,13 @@ int xe_mmio_probe_vram(struct xe_device *xe)
 		xe->mem.vram.mapping = 0;
 		xe->mem.vram.size = 0;
 		xe->mem.vram.io_start = 0;
+		xe->mem.vram.io_size = 0;
 
 		for_each_gt(gt, xe, id) {
 			gt->mem.vram.mapping = 0;
 			gt->mem.vram.size = 0;
 			gt->mem.vram.io_start = 0;
+			gt->mem.vram.io_size = 0;
 		}
 		return 0;
 	}
@@ -212,10 +213,10 @@ int xe_mmio_probe_vram(struct xe_device *xe)
 		return err;
 
 	resize_result = xe_resize_vram_bar(xe, vram_size);
-	current_size = pci_resource_len(pdev, GEN12_LMEM_BAR);
 	xe->mem.vram.io_start = pci_resource_start(pdev, GEN12_LMEM_BAR);
-
-	xe->mem.vram.size = min(current_size, vram_size);
+	xe->mem.vram.io_size = min(usable_size,
+				   pci_resource_len(pdev, GEN12_LMEM_BAR));
+	xe->mem.vram.size = xe->mem.vram.io_size;
 
 	if (!xe->mem.vram.size)
 		return -EIO;
@@ -223,15 +224,15 @@ int xe_mmio_probe_vram(struct xe_device *xe)
 	if (resize_result > 0)
 		drm_info(&xe->drm, "Successfully resize VRAM from %lluMiB to %lluMiB\n",
 			 (u64)original_size >> 20,
-			 (u64)current_size >> 20);
-	else if (xe->mem.vram.size < vram_size && !xe_force_vram_bar_size)
+			 (u64)xe->mem.vram.io_size >> 20);
+	else if (xe->mem.vram.io_size < usable_size && !xe_force_vram_bar_size)
 		drm_info(&xe->drm, "Using a reduced BAR size of %lluMiB. Consider enabling 'Resizable BAR' support in your BIOS.\n",
 			 (u64)xe->mem.vram.size >> 20);
 	if (xe->mem.vram.size < vram_size)
 		drm_warn(&xe->drm, "Restricting VRAM size to PCI resource size (0x%llx->0x%llx)\n",
 			 vram_size, (u64)xe->mem.vram.size);
 
-	xe->mem.vram.mapping = ioremap_wc(xe->mem.vram.io_start, xe->mem.vram.size);
+	xe->mem.vram.mapping = ioremap_wc(xe->mem.vram.io_start, xe->mem.vram.io_size);
 	xe->mem.vram.size = min_t(u64, xe->mem.vram.size, usable_size);
 
 	drm_info(&xe->drm, "TOTAL VRAM: %pa, %pa\n", &xe->mem.vram.io_start, &xe->mem.vram.size);
@@ -239,7 +240,7 @@ int xe_mmio_probe_vram(struct xe_device *xe)
 	/* FIXME: Assuming equally partitioned VRAM, incorrect */
 	if (xe->info.tile_count > 1) {
 		u8 adj_tile_count = xe->info.tile_count;
-		resource_size_t size, io_start;
+		resource_size_t size, io_start, io_size;
 
 		for_each_gt(gt, xe, id)
 			if (xe_gt_is_media_type(gt))
@@ -249,15 +250,31 @@ int xe_mmio_probe_vram(struct xe_device *xe)
 
 		size = xe->mem.vram.size / adj_tile_count;
 		io_start = xe->mem.vram.io_start;
+		io_size = xe->mem.vram.io_size;
 
 		for_each_gt(gt, xe, id) {
-			if (id && !xe_gt_is_media_type(gt))
-				io_start += size;
+			if (id && !xe_gt_is_media_type(gt)) {
+				io_size -= min(io_size, size);
+				io_start += io_size;
+			}
 
 			gt->mem.vram.size = size;
-			gt->mem.vram.io_start = io_start;
-			gt->mem.vram.mapping = xe->mem.vram.mapping +
-				(io_start - xe->mem.vram.io_start);
+
+			/*
+			 * XXX: multi-tile small-bar might be wild. Hopefully
+			 * full tile without any mappable vram is not something
+			 * we care about.
+			 */
+
+			gt->mem.vram.io_size = min(size, io_size);
+			if (io_size) {
+				gt->mem.vram.io_start = io_start;
+				gt->mem.vram.mapping = xe->mem.vram.mapping +
+					(io_start - xe->mem.vram.io_start);
+			} else {
+				drm_err(&xe->drm, "Tile without any CPU visible VRAM. Aborting.\n");
+				return -ENODEV;
+			}
 
 			drm_info(&xe->drm, "VRAM[%u, %u]: %pa, %pa\n",
 				 id, gt->info.vram_id, &gt->mem.vram.io_start,
@@ -266,6 +283,7 @@ int xe_mmio_probe_vram(struct xe_device *xe)
 	} else {
 		gt->mem.vram.size = xe->mem.vram.size;
 		gt->mem.vram.io_start = xe->mem.vram.io_start;
+		gt->mem.vram.io_size = xe->mem.vram.io_size;
 		gt->mem.vram.mapping = xe->mem.vram.mapping;
 
 		drm_info(&xe->drm, "VRAM: %pa\n", &gt->mem.vram.size);