linux-kernel - [PATCH 4/4] x86/nmi: Convert nmi_cr2/nmi

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Message-Id: <20211213150340.9419-5-jiangshanlai@gmail.com>
Date:   Mon, 13 Dec 2021 23:03:40 +0800
From:   Lai Jiangshan <jiangshanlai@...il.com>
To:     linux-kernel@...r.kernel.org
Cc:     x86@...nel.org, Lai Jiangshan <laijs@...ux.alibaba.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        "H. Peter Anvin" <hpa@...or.com>, Joerg Roedel <jroedel@...e.de>,
        Brijesh Singh <brijesh.singh@....com>
Subject: [PATCH 4/4] x86/nmi: Convert nmi_cr2/nmi_dr7 to be func-local variable

From: Lai Jiangshan <laijs@...ux.alibaba.com>

nmi_cr2 and nmi_dr7 are used inside a function (the outmost exc_nmi()),
they don't need to be percpu data.

Signed-off-by: Lai Jiangshan <laijs@...ux.alibaba.com>
---
 arch/x86/kernel/nmi.c | 14 +++++++-------
 1 file changed, 7 insertions(+), 7 deletions(-)

diff --git a/arch/x86/kernel/nmi.c b/arch/x86/kernel/nmi.c
index 44c3adb68282..673eee5831db 100644
--- a/arch/x86/kernel/nmi.c
+++ b/arch/x86/kernel/nmi.c
@@ -470,12 +470,12 @@ enum nmi_states {
 	NMI_LATCHED,
 };
 static DEFINE_PER_CPU(enum nmi_states, nmi_state);
-static DEFINE_PER_CPU(unsigned long, nmi_cr2);
-static DEFINE_PER_CPU(unsigned long, nmi_dr7);
 
 DEFINE_IDTENTRY_NMI(exc_nmi)
 {
 	irqentry_state_t irq_state;
+	unsigned long nmi_cr2;
+	unsigned long nmi_dr7;
 
 	/*
 	 * Re-enable NMIs right here when running as an SEV-ES guest. This might
@@ -491,7 +491,7 @@ DEFINE_IDTENTRY_NMI(exc_nmi)
 		return;
 	}
 	this_cpu_write(nmi_state, NMI_EXECUTING);
-	this_cpu_write(nmi_cr2, read_cr2());
+	nmi_cr2 = read_cr2();
 nmi_restart:
 
 	/*
@@ -500,7 +500,7 @@ DEFINE_IDTENTRY_NMI(exc_nmi)
 	 */
 	sev_es_ist_enter(regs);
 
-	this_cpu_write(nmi_dr7, local_db_save());
+	nmi_dr7 = local_db_save();
 
 	irq_state = irqentry_nmi_enter(regs);
 
@@ -511,12 +511,12 @@ DEFINE_IDTENTRY_NMI(exc_nmi)
 
 	irqentry_nmi_exit(regs, irq_state);
 
-	local_db_restore(this_cpu_read(nmi_dr7));
+	local_db_restore(nmi_dr7);
 
 	sev_es_ist_exit();
 
-	if (unlikely(this_cpu_read(nmi_cr2) != read_cr2()))
-		write_cr2(this_cpu_read(nmi_cr2));
+	if (unlikely(nmi_cr2 != read_cr2()))
+		write_cr2(nmi_cr2);
 	if (this_cpu_dec_return(nmi_state))
 		goto nmi_restart;
 
-- 
2.19.1.6.gb485710b