sched/cache: Keep nr_pref_llc_running in the runnable domain, to fix LLC mis-scheduling buggrafted

alb_break_llc() decides whether to break LLC preference during active
load balance. It does so by testing that every runnable fair task on the
source rq prefers its LLC:

	env->src_rq->nr_pref_llc_running == env->src_rq->cfs.h_nr_runnable

But the two counters cover different sets. nr_pref_llc_running is updated
in account_llc_enqueue()/account_llc_dequeue(), next to cfs_rq->nr_queued,
so it follows queued tasks. h_nr_runnable is updated in set_delayed()/
clear_delayed() and drops delay-dequeued tasks.

So under DELAY_DEQUEUE, a preferring task that goes to sleep stays counted
in nr_pref_llc_running while h_nr_runnable falls. The equality then breaks,
alb_break_llc() returns false, and active balance is free to pull a task
off its preferred LLC. Active balance only moves runnable tasks, and this
is the only LLC check it consults: once the stopper runs, LBF_ACTIVE_LB
skips the per-task test in can_migrate_task(). The runnable set is the one
we want.

Fix it on the counter side. A task should be counted in
nr_pref_llc_running exactly while it is both queued on its preferred LLC
(pref_llc_queued) and runnable (!sched_delayed). Define that membership
once in task_pref_llc_runnable(), and adjust the counter only through
pref_llc_running_inc()/pref_llc_running_dec() from the four sites that
change either input: account_llc_enqueue(), account_llc_dequeue(),
set_delayed() and clear_delayed(). Gating every update on the same
predicate keeps the delay, wake and dequeue paths from double-counting
or underflowing; see the comments at those sites for the ordering.

nr_llc_running and sd->llc_counts are not touched and stay on queued
semantics.

Fixes: 714059f79ff0 ("sched/cache: Handle moving single tasks to/from their preferred LLC")
Closes: https://lore.kernel.org/lkml/20260827135000.735138-1-zhanxusheng@xiaomi.com/
Reported-by: Zhan Xusheng <zhanxusheng@xiaomi.com>
Suggested-by: Chen Yu <yu.c.chen@intel.com>
Signed-off-by: Tim Chen <tim.c.chen@linux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Kayra Cizmeci <kayracizmeci@gmail.com>
Cc: <stable@kernel.org> # v7.2.x
Link: https://patch.msgid.link/06af61afedac32e6477f57feb4d658f6c411c3af.1790035273.git.tim.c.chen@linux.intel.com

1 files changed, 137 insertions, 0 deletions

diff --git a/drivers/crypto/ccp/psp-dev.h b/drivers/crypto/ccp/psp-dev.h
new file mode 100644
index 000000000..4e370e76b
--- /dev/null
+++ b/drivers/crypto/ccp/psp-dev.h
@@ -0,0 +1,137 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * AMD Platform Security Processor (PSP) interface driver
+ *
+ * Copyright (C) 2017-2019 Advanced Micro Devices, Inc.
+ *
+ * Author: Brijesh Singh <brijesh.singh@amd.com>
+ */
+
+#ifndef __PSP_DEV_H__
+#define __PSP_DEV_H__
+
+#include <linux/device.h>
+#include <linux/list.h>
+#include <linux/bits.h>
+#include <linux/interrupt.h>
+#include <linux/mutex.h>
+#include <linux/psp.h>
+#include <linux/psp-platform-access.h>
+
+#include "sp-dev.h"
+
+#define MAX_PSP_NAME_LEN		16
+
+extern struct psp_device *psp_master;
+
+typedef void (*psp_irq_handler_t)(int, void *, unsigned int);
+
+union psp_cap_register {
+	unsigned int raw;
+	struct {
+		unsigned int sev			:1,
+			     tee			:1,
+			     dbc_thru_ext		:1,
+			     sfs			:1,
+			     rsvd1			:3,
+			     security_reporting		:1,
+			     fused_part			:1,
+			     boot_integrity		:1,
+			     debug_lock_on		:1,
+			     rsvd3			:2,
+			     tsme_status		:1,
+			     rsvd4			:1,
+			     anti_rollback_status	:1,
+			     rpmc_production_enabled	:1,
+			     rpmc_spirom_available	:1,
+			     hsp_tpm_available		:1,
+			     rom_armor_enforced		:1,
+			     rsvd5			:12;
+	};
+};
+
+struct psp_device {
+	struct list_head entry;
+
+	struct psp_vdata *vdata;
+	char name[MAX_PSP_NAME_LEN];
+
+	struct device *dev;
+	struct sp_device *sp;
+
+	void __iomem *io_regs;
+	struct mutex mailbox_mutex;
+
+	psp_irq_handler_t sev_irq_handler;
+	void *sev_irq_data;
+
+	void *sev_data;
+	void *tee_data;
+	void *platform_access_data;
+	void *dbc_data;
+	void *sfs_data;
+
+	union psp_cap_register capability;
+};
+
+void psp_set_sev_irq_handler(struct psp_device *psp, psp_irq_handler_t handler,
+			     void *data);
+void psp_clear_sev_irq_handler(struct psp_device *psp);
+
+struct psp_device *psp_get_master_device(void);
+
+/**
+ * enum psp_cmd - PSP mailbox commands
+ * @PSP_CMD_TEE_RING_INIT:	Initialize TEE ring buffer
+ * @PSP_CMD_TEE_RING_DESTROY:	Destroy TEE ring buffer
+ * @PSP_CMD_TEE_EXTENDED_CMD:	Extended command
+ * @PSP_CMD_MAX:		Maximum command id
+ */
+enum psp_cmd {
+	PSP_CMD_TEE_RING_INIT		= 1,
+	PSP_CMD_TEE_RING_DESTROY	= 2,
+	PSP_CMD_TEE_EXTENDED_CMD	= 14,
+	PSP_CMD_MAX			= 15,
+};
+
+int psp_mailbox_command(struct psp_device *psp, enum psp_cmd cmd, void *cmdbuff,
+			unsigned int timeout_msecs, unsigned int *cmdresp);
+
+/**
+ * struct psp_ext_req_buffer_hdr - Structure of the extended command header
+ * @payload_size: total payload size
+ * @sub_cmd_id: extended command ID
+ * @status: status of command execution (out)
+ */
+struct psp_ext_req_buffer_hdr {
+	u32 payload_size;
+	u32 sub_cmd_id;
+	u32 status;
+} __packed;
+
+struct psp_ext_request {
+	struct psp_ext_req_buffer_hdr header;
+	void *buf;
+} __packed;
+
+/**
+ * enum psp_sub_cmd - PSP mailbox sub commands
+ * @PSP_SUB_CMD_DBC_GET_NONCE:		Get nonce from DBC
+ * @PSP_SUB_CMD_DBC_SET_UID:		Set UID for DBC
+ * @PSP_SUB_CMD_DBC_GET_PARAMETER:	Get parameter from DBC
+ * @PSP_SUB_CMD_DBC_SET_PARAMETER:	Set parameter for DBC
+ * @PSP_SUB_CMD_SFS_GET_FW_VERS:	Get firmware versions for ASP and other MP
+ * @PSP_SUB_CMD_SFS_UPDATE:		Command to load, verify and execute SFS package
+ */
+enum psp_sub_cmd {
+	PSP_SUB_CMD_DBC_GET_NONCE	= PSP_DYNAMIC_BOOST_GET_NONCE,
+	PSP_SUB_CMD_DBC_SET_UID		= PSP_DYNAMIC_BOOST_SET_UID,
+	PSP_SUB_CMD_DBC_GET_PARAMETER	= PSP_DYNAMIC_BOOST_GET_PARAMETER,
+	PSP_SUB_CMD_DBC_SET_PARAMETER	= PSP_DYNAMIC_BOOST_SET_PARAMETER,
+	PSP_SUB_CMD_SFS_GET_FW_VERS	= PSP_SFS_GET_FW_VERSIONS,
+	PSP_SUB_CMD_SFS_UPDATE		= PSP_SFS_UPDATE,
+};
+
+int psp_extended_mailbox_cmd(struct psp_device *psp, unsigned int timeout_msecs,
+			     struct psp_ext_request *req);
+#endif /* __PSP_DEV_H */