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, 198 insertions, 0 deletions

diff --git a/include/net/flow.h b/include/net/flow.h
new file mode 100644
index 000000000..ae9481c40
--- /dev/null
+++ b/include/net/flow.h
@@ -0,0 +1,198 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ *
+ *	Generic internet FLOW.
+ *
+ */
+
+#ifndef _NET_FLOW_H
+#define _NET_FLOW_H
+
+#include <linux/in6.h>
+#include <linux/atomic.h>
+#include <linux/container_of.h>
+#include <linux/uidgid.h>
+#include <net/inet_dscp.h>
+
+struct flow_keys;
+
+/*
+ * ifindex generation is per-net namespace, and loopback is
+ * always the 1st device in ns (see net_dev_init), thus any
+ * loopback device should get ifindex 1
+ */
+
+#define LOOPBACK_IFINDEX	1
+
+struct flowi_tunnel {
+	__be64			tun_id;
+};
+
+struct flowi_common {
+	int	flowic_oif;
+	int	flowic_iif;
+	int     flowic_l3mdev;
+	__u32	flowic_mark;
+	dscp_t	flowic_dscp;
+	__u8	flowic_scope;
+	__u8	flowic_proto;
+	__u8	flowic_flags;
+#define FLOWI_FLAG_ANYSRC		0x01
+#define FLOWI_FLAG_KNOWN_NH		0x02
+#define FLOWI_FLAG_L3MDEV_OIF		0x04
+#define FLOWI_FLAG_ANY_SPORT		0x08
+	__u32	flowic_secid;
+	kuid_t  flowic_uid;
+	__u32		flowic_multipath_hash;
+	struct flowi_tunnel flowic_tun_key;
+};
+
+union flowi_uli {
+	struct {
+		__be16	dport;
+		__be16	sport;
+	} ports;
+
+	struct {
+		__u8	type;
+		__u8	code;
+	} icmpt;
+
+	__be32		gre_key;
+
+	struct {
+		__u8	type;
+	} mht;
+};
+
+struct flowi4 {
+	struct flowi_common	__fl_common;
+#define flowi4_oif		__fl_common.flowic_oif
+#define flowi4_iif		__fl_common.flowic_iif
+#define flowi4_l3mdev		__fl_common.flowic_l3mdev
+#define flowi4_mark		__fl_common.flowic_mark
+#define flowi4_dscp		__fl_common.flowic_dscp
+#define flowi4_scope		__fl_common.flowic_scope
+#define flowi4_proto		__fl_common.flowic_proto
+#define flowi4_flags		__fl_common.flowic_flags
+#define flowi4_secid		__fl_common.flowic_secid
+#define flowi4_tun_key		__fl_common.flowic_tun_key
+#define flowi4_uid		__fl_common.flowic_uid
+#define flowi4_multipath_hash	__fl_common.flowic_multipath_hash
+
+	/* (saddr,daddr) must be grouped, same order as in IP header */
+	__be32			saddr;
+	__be32			daddr;
+
+	union flowi_uli		uli;
+#define fl4_sport		uli.ports.sport
+#define fl4_dport		uli.ports.dport
+#define fl4_icmp_type		uli.icmpt.type
+#define fl4_icmp_code		uli.icmpt.code
+#define fl4_mh_type		uli.mht.type
+#define fl4_gre_key		uli.gre_key
+} __attribute__((__aligned__(BITS_PER_LONG/8)));
+
+static inline void flowi4_init_output(struct flowi4 *fl4, int oif,
+				      __u32 mark, __u8 tos, __u8 scope,
+				      __u8 proto, __u8 flags,
+				      __be32 daddr, __be32 saddr,
+				      __be16 dport, __be16 sport,
+				      kuid_t uid)
+{
+	fl4->flowi4_oif = oif;
+	fl4->flowi4_iif = LOOPBACK_IFINDEX;
+	fl4->flowi4_l3mdev = 0;
+	fl4->flowi4_mark = mark;
+	fl4->flowi4_dscp = inet_dsfield_to_dscp(tos);
+	fl4->flowi4_scope = scope;
+	fl4->flowi4_proto = proto;
+	fl4->flowi4_flags = flags;
+	fl4->flowi4_secid = 0;
+	fl4->flowi4_tun_key.tun_id = 0;
+	fl4->flowi4_uid = uid;
+	fl4->daddr = daddr;
+	fl4->saddr = saddr;
+	fl4->fl4_dport = dport;
+	fl4->fl4_sport = sport;
+	fl4->flowi4_multipath_hash = 0;
+}
+
+/* Reset some input parameters after previous lookup */
+static inline void flowi4_update_output(struct flowi4 *fl4, int oif,
+					__be32 daddr, __be32 saddr)
+{
+	fl4->flowi4_oif = oif;
+	fl4->daddr = daddr;
+	fl4->saddr = saddr;
+}
+
+
+struct flowi6 {
+	struct flowi_common	__fl_common;
+#define flowi6_oif		__fl_common.flowic_oif
+#define flowi6_iif		__fl_common.flowic_iif
+#define flowi6_l3mdev		__fl_common.flowic_l3mdev
+#define flowi6_mark		__fl_common.flowic_mark
+#define flowi6_scope		__fl_common.flowic_scope
+#define flowi6_proto		__fl_common.flowic_proto
+#define flowi6_flags		__fl_common.flowic_flags
+#define flowi6_secid		__fl_common.flowic_secid
+#define flowi6_tun_key		__fl_common.flowic_tun_key
+#define flowi6_uid		__fl_common.flowic_uid
+	struct in6_addr		daddr;
+	struct in6_addr		saddr;
+	/* Note: flowi6_dscp is encoded in flowlabel, too. */
+	__be32			flowlabel;
+	union flowi_uli		uli;
+#define fl6_sport		uli.ports.sport
+#define fl6_dport		uli.ports.dport
+#define fl6_icmp_type		uli.icmpt.type
+#define fl6_icmp_code		uli.icmpt.code
+#define fl6_mh_type		uli.mht.type
+#define fl6_gre_key		uli.gre_key
+	__u32			mp_hash;
+} __attribute__((__aligned__(BITS_PER_LONG/8)));
+
+struct flowi {
+	union {
+		struct flowi_common	__fl_common;
+		struct flowi4		ip4;
+		struct flowi6		ip6;
+	} u;
+#define flowi_oif	u.__fl_common.flowic_oif
+#define flowi_iif	u.__fl_common.flowic_iif
+#define flowi_l3mdev	u.__fl_common.flowic_l3mdev
+#define flowi_mark	u.__fl_common.flowic_mark
+#define flowi_dscp	u.__fl_common.flowic_dscp
+#define flowi_scope	u.__fl_common.flowic_scope
+#define flowi_proto	u.__fl_common.flowic_proto
+#define flowi_flags	u.__fl_common.flowic_flags
+#define flowi_secid	u.__fl_common.flowic_secid
+#define flowi_tun_key	u.__fl_common.flowic_tun_key
+#define flowi_uid	u.__fl_common.flowic_uid
+} __attribute__((__aligned__(BITS_PER_LONG/8)));
+
+static inline struct flowi *flowi4_to_flowi(struct flowi4 *fl4)
+{
+	return container_of(fl4, struct flowi, u.ip4);
+}
+
+static inline struct flowi_common *flowi4_to_flowi_common(struct flowi4 *fl4)
+{
+	return &(fl4->__fl_common);
+}
+
+static inline struct flowi *flowi6_to_flowi(struct flowi6 *fl6)
+{
+	return container_of(fl6, struct flowi, u.ip6);
+}
+
+static inline struct flowi_common *flowi6_to_flowi_common(struct flowi6 *fl6)
+{
+	return &(fl6->__fl_common);
+}
+
+__u32 __get_hash_from_flowi6(const struct flowi6 *fl6, struct flow_keys *keys);
+
+#endif