drm/xe/guc: Ratelimit diagnostic messages from the relay

There might be some malicious VFs that by sending an invalid VF2PF
relay messages will flood PF's dmesg with our diagnostics messages.

Rate limit all relay messages, unless running in DEBUG_SRIOV mode.

Signed-off-by: Michal Wajdeczko <[e-mail]>
Reviewed-by: Piotr Piórkowski <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]

drivers/gpu/drm/xe/xe_guc_relay.c

···
 	return gt_to_xe(relay_to_gt(relay));
 }
 
+#define XE_RELAY_DIAG_RATELIMIT_INTERVAL	(10 * HZ)
+#define XE_RELAY_DIAG_RATELIMIT_BURST		10
+
+#define relay_ratelimit_printk(relay, _level, fmt...) ({			\
+	typeof(relay) _r = (relay);						\
+	if (IS_ENABLED(CONFIG_DRM_XE_DEBUG_SRIOV) ||				\
+	    ___ratelimit(&_r->diag_ratelimit, "xe_guc_relay"))			\
+		xe_gt_sriov_##_level(relay_to_gt(_r), "relay: " fmt);		\
+})
+
 #define relay_assert(relay, condition)	xe_gt_assert(relay_to_gt(relay), condition)
-#define relay_notice(relay, msg...)	xe_gt_sriov_notice(relay_to_gt(relay), "relay: " msg)
-#define relay_debug(relay, msg...)	xe_gt_sriov_dbg_verbose(relay_to_gt(relay), "relay: " msg)
+#define relay_notice(relay, msg...)	relay_ratelimit_printk((relay), notice, msg)
+#define relay_debug(relay, msg...)	relay_ratelimit_printk((relay), dbg_verbose, msg)
 
 static int relay_get_totalvfs(struct xe_guc_relay *relay)
 {
···
 	INIT_WORK(&relay->worker, relays_worker_fn);
 	INIT_LIST_HEAD(&relay->pending_relays);
 	INIT_LIST_HEAD(&relay->incoming_actions);
+	ratelimit_state_init(&relay->diag_ratelimit,
+			     XE_RELAY_DIAG_RATELIMIT_INTERVAL,
+			     XE_RELAY_DIAG_RATELIMIT_BURST);
 
 	err = mempool_init_kmalloc_pool(&relay->pool, XE_RELAY_MEMPOOL_MIN_NUM +
 					relay_get_totalvfs(relay),

drivers/gpu/drm/xe/xe_guc_relay_types.h

···
 #define _XE_GUC_RELAY_TYPES_H_
 
 #include <linux/mempool.h>
+#include <linux/ratelimit_types.h>
 #include <linux/spinlock.h>
 #include <linux/workqueue.h>
 
···
 
 	/** @last_rid: last Relay-ID used while sending a message. */
 	u32 last_rid;
+
+	/** @diag_ratelimit: ratelimit state used to throttle diagnostics messages. */
+	struct ratelimit_state diag_ratelimit;
 };
 
 #endif