From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: stable@vger.kernel.org
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	patches@lists.linux.dev,
	Thomas Richter <tmricht@linux.ibm.com>,
	Heiko Carstens <hca@linux.ibm.com>,
	Sasha Levin <sashal@kernel.org>
Subject: [PATCH 6.1 096/303] s390/cpum_cf: remove in-kernel counting facility interface
Date: Thu, 20 Aug 2026 16:53:52 +0200
Message-ID: <20260820145256.178986174@linuxfoundation.org>
In-Reply-To: <20260820145253.200766705@linuxfoundation.org>
References: <20260820145253.200766705@linuxfoundation.org>
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6.1-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Thomas Richter <tmricht@linux.ibm.com>

[ Upstream commit ea53e6995f45e857fd34e4fbfbd436b5457da5f7 ]

Commit 17bebcc68eee ("s390/cpum_cf: Add minimal in-kernel interface for
counter measurements") introduced a small in-kernel interface for CPU
Measurement counter facility.
There are no users of this interface, therefore remove it.

The following functions are removed:
 kernel_cpumcf_alert(),
 kernel_cpumcf_begin(),
 kernel_cpumcf_end(),
 kernel_cpumcf_avail()
there is no need for them anymore.
With the removal of function kernel_cpumcf_alert(), also remove
member alert in struct cpu_cf_events. Its purpose was to counter
measurement alert interrupts for the in-kernel interface.

Signed-off-by: Thomas Richter <tmricht@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Stable-dep-of: 49145bce5391 ("s390/perf_cpum_cf: Add missing array_index_nospec() to __hw_perf_event_init()")
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 arch/s390/include/asm/cpu_mcf.h        |   17 -----------------
 arch/s390/kernel/perf_cpum_cf.c        |    2 +-
 arch/s390/kernel/perf_cpum_cf_common.c |   24 ------------------------
 3 files changed, 1 insertion(+), 42 deletions(-)

--- a/arch/s390/include/asm/cpu_mcf.h
+++ b/arch/s390/include/asm/cpu_mcf.h
@@ -67,7 +67,6 @@ static inline int ctr_stcctm(enum cpumf_
 struct cpu_cf_events {
 	struct cpumf_ctr_info	info;
 	atomic_t		ctr_set[CPUMF_CTR_SET_MAX];
-	atomic64_t		alert;
 	u64			state;		/* For perf_event_open SVC */
 	u64			dev_state;	/* For /dev/hwctr */
 	unsigned int		flags;
@@ -80,25 +79,9 @@ struct cpu_cf_events {
 };
 DECLARE_PER_CPU(struct cpu_cf_events, cpu_cf_events);
 
-bool kernel_cpumcf_avail(void);
 int __kernel_cpumcf_begin(void);
-unsigned long kernel_cpumcf_alert(int clear);
 void __kernel_cpumcf_end(void);
 
-static inline int kernel_cpumcf_begin(void)
-{
-	if (!cpum_cf_avail())
-		return -ENODEV;
-
-	preempt_disable();
-	return __kernel_cpumcf_begin();
-}
-static inline void kernel_cpumcf_end(void)
-{
-	__kernel_cpumcf_end();
-	preempt_enable();
-}
-
 int cfset_online_cpu(unsigned int cpu);
 int cfset_offline_cpu(unsigned int cpu);
 #endif /* _ASM_S390_CPU_MCF_H */
--- a/arch/s390/kernel/perf_cpum_cf.c
+++ b/arch/s390/kernel/perf_cpum_cf.c
@@ -832,7 +832,7 @@ static int __init cpumf_pmu_init(void)
 {
 	int rc;
 
-	if (!kernel_cpumcf_avail())
+	if (!cpum_cf_avail())
 		return -ENODEV;
 
 	/* Setup s390dbf facility */
--- a/arch/s390/kernel/perf_cpum_cf_common.c
+++ b/arch/s390/kernel/perf_cpum_cf_common.c
@@ -27,7 +27,6 @@ DEFINE_PER_CPU(struct cpu_cf_events, cpu
 		[CPUMF_CTR_SET_EXT]	= ATOMIC_INIT(0),
 		[CPUMF_CTR_SET_MT_DIAG] = ATOMIC_INIT(0),
 	},
-	.alert = ATOMIC64_INIT(0),
 	.state = 0,
 	.dev_state = 0,
 	.flags = 0,
@@ -67,9 +66,6 @@ static void cpumf_measurement_alert(stru
 	if (alert & CPU_MF_INT_CF_MTDA)
 		pr_warn("CPU[%i] MT counter data was lost\n",
 			smp_processor_id());
-
-	/* store alert for special handling by in-kernel users */
-	atomic64_or(alert, &cpuhw->alert);
 }
 
 #define PMC_INIT      0
@@ -94,12 +90,6 @@ static void cpum_cf_setup_cpu(void *flag
 	lcctl(0);
 }
 
-bool kernel_cpumcf_avail(void)
-{
-	return cpum_cf_initalized;
-}
-EXPORT_SYMBOL(kernel_cpumcf_avail);
-
 /* Initialize the CPU-measurement counter facility */
 int __kernel_cpumcf_begin(void)
 {
@@ -112,20 +102,6 @@ int __kernel_cpumcf_begin(void)
 }
 EXPORT_SYMBOL(__kernel_cpumcf_begin);
 
-/* Obtain the CPU-measurement alerts for the counter facility */
-unsigned long kernel_cpumcf_alert(int clear)
-{
-	struct cpu_cf_events *cpuhw = this_cpu_ptr(&cpu_cf_events);
-	unsigned long alert;
-
-	alert = atomic64_read(&cpuhw->alert);
-	if (clear)
-		atomic64_set(&cpuhw->alert, 0);
-
-	return alert;
-}
-EXPORT_SYMBOL(kernel_cpumcf_alert);
-
 /* Release the CPU-measurement counter facility */
 void __kernel_cpumcf_end(void)
 {