x86/amd_node: Fix PCI device reference counting in amd_smn_init()grafted

The local "root" pointer is a temporary variable used during the device
search. Therefore, refcount related to the search iterators should be cleaned
up after the search is complete.

Use the __free() cleanup macro to ensure the refcount is decremented when the
temporary pointer goes out of scope.

Additionally, increment the refcount when caching a root pointer. This ensures
the in-use refcount is separate from the temporary search refcounting.

Finally, drop the redundant "root = NULL" before the second search loop. The
pci_get_class() iterator always decrements the refcount of its "from"
argument, so the first loop can only fall through with "root" already NULL.

Fixes: 0a4b61d9c2e4 ("x86/amd_node: Fix AMD root device caching")
Closes: https://sashiko.dev/#/patchset/20260806160159.230453-1-jason.andryuk%40amd.com
Reported-by: Sashiko <sashiko-bot@kernel.org>
Assisted-by: LLM
Signed-off-by: Yazen Ghannam <yazen.ghannam@amd.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: Mario Limonciello (AMD) <superm1@kernel.org>
Cc: <stable@kernel.org>
Link: https://patch.msgid.link/20260903154325.74343-1-yazen.ghannam@amd.com

1 files changed, 53 insertions, 0 deletions

diff --git a/drivers/dma/idxd/defaults.c b/drivers/dma/idxd/defaults.c
new file mode 100644
index 000000000..26ebfa2ca
--- /dev/null
+++ b/drivers/dma/idxd/defaults.c
@@ -0,0 +1,53 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright(c) 2023 Intel Corporation. All rights rsvd. */
+#include <linux/kernel.h>
+#include "idxd.h"
+
+int idxd_load_iaa_device_defaults(struct idxd_device *idxd)
+{
+	struct idxd_engine *engine;
+	struct idxd_group *group;
+	struct idxd_wq *wq;
+	int i;
+
+	if (!test_bit(IDXD_FLAG_CONFIGURABLE, &idxd->flags))
+		return 0;
+
+	wq = idxd->wqs[0];
+
+	if (wq->state != IDXD_WQ_DISABLED)
+		return -EPERM;
+
+	/* set mode to "dedicated" */
+	set_bit(WQ_FLAG_DEDICATED, &wq->flags);
+	wq->threshold = 0;
+
+	/* only setting up 1 wq, so give it all the wq space */
+	wq->size = idxd->max_wq_size;
+
+	/* set priority to 10 */
+	wq->priority = 10;
+
+	/* set type to "kernel" */
+	wq->type = IDXD_WQT_KERNEL;
+
+	/* set wq group to 0 */
+	group = idxd->groups[0];
+	wq->group = group;
+	group->num_wqs++;
+
+	/* set name to "iaa_crypto" */
+	strscpy_pad(wq->name, "iaa_crypto");
+
+	/* set driver_name to "crypto" */
+	strscpy_pad(wq->driver_name, "crypto");
+
+	/* assign all engines to group 0 */
+	for (i = 0; i < idxd->max_engines; i++) {
+		engine = idxd->engines[i];
+		engine->group = group;
+		group->num_engines++;
+	}
+
+	return 0;
+}