linux-kernel - [PATCH][RFC] x86,lib: Add wbinvd_on_many

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Date: Tue,  9 Apr 2024 12:20:56 +0800
From: Li RongQing <lirongqing@...du.com>
To: tglx@...utronix.de,
	mingo@...hat.com,
	bp@...en8.de,
	dave.hansen@...ux.intel.com,
	x86@...nel.org,
	peterz@...radead.org,
	linux-kernel@...r.kernel.org,
	pbonzini@...hat.com,
	kvm@...r.kernel.org,
	seanjc@...gle.com,
	szy0127@...u.edu.cn,
	thomas.lendacky@....com
Cc: Li RongQing <lirongqing@...du.com>
Subject: [PATCH][RFC] x86,lib: Add wbinvd_on_many_cpus helpers

wbinvd_on_many_cpus will call smp_call_function_many(), which should
be more efficient that iterating cpus since it would run wbinvd()
concurrently locally and remotely

it can be used by the below patch
https://patchwork.kernel.org/project/kvm/patch/1860502863.219296.1710395908135.JavaMail.zimbra@sjtu.edu.cn/

Cc: Zheyun Shen <szy0127@...u.edu.cn>
Cc: Tom Lendacky <thomas.lendacky@....com>
Signed-off-by: Li RongQing <lirongqing@...du.com>
---
 arch/x86/include/asm/smp.h | 7 +++++++
 arch/x86/lib/cache-smp.c   | 7 +++++++
 2 files changed, 14 insertions(+)

diff --git a/arch/x86/include/asm/smp.h b/arch/x86/include/asm/smp.h
index a35936b..70973de 100644
--- a/arch/x86/include/asm/smp.h
+++ b/arch/x86/include/asm/smp.h
@@ -111,6 +111,7 @@ void native_play_dead(void);
 void play_dead_common(void);
 void wbinvd_on_cpu(int cpu);
 int wbinvd_on_all_cpus(void);
+int wbinvd_on_many_cpus(const struct cpumask *mask);
 
 void smp_kick_mwait_play_dead(void);
 
@@ -159,6 +160,12 @@ static inline int wbinvd_on_all_cpus(void)
 	return 0;
 }
 
+static inline int wbinvd_on_many_cpus(const struct cpumask *mask)
+{
+	wbinvd();
+	return 0;
+}
+
 static inline struct cpumask *cpu_llc_shared_mask(int cpu)
 {
 	return (struct cpumask *)cpumask_of(0);
diff --git a/arch/x86/lib/cache-smp.c b/arch/x86/lib/cache-smp.c
index 7af743b..5950d1b 100644
--- a/arch/x86/lib/cache-smp.c
+++ b/arch/x86/lib/cache-smp.c
@@ -20,3 +20,10 @@ int wbinvd_on_all_cpus(void)
 	return 0;
 }
 EXPORT_SYMBOL(wbinvd_on_all_cpus);
+
+int wbinvd_on_many_cpus(const struct cpumask *mask)
+{
+	smp_call_function_many(mask, __wbinvd, NULL, 1);
+	return 0;
+}
+EXPORT_SYMBOL(wbinvd_on_many_cpus);
-- 
2.9.4