linux-kernel - [PATCH 2/2] x86/machine_kexec: disable PMU before jumping to new kernel

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Date:   Mon, 23 Nov 2020 13:37:26 +0800
From:   Pingfan Liu <kernelfans@...il.com>
To:     x86@...nel.org
Cc:     Pingfan Liu <kernelfans@...il.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...hat.com>,
        Arnaldo Carvalho de Melo <acme@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Jiri Olsa <jolsa@...hat.com>,
        Namhyung Kim <namhyung@...nel.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Borislav Petkov <bp@...en8.de>,
        "H. Peter Anvin" <hpa@...or.com>, Omar Sandoval <osandov@...com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Mike Rapoport <rppt@...nel.org>, linux-kernel@...r.kernel.org
Subject: [PATCH 2/2] x86/machine_kexec: disable PMU before jumping to new kernel

During jumping to the new kernel, on the crashed cpu, the memory mapping
switches from an old one to an identity one. It had better disable PMU to
suppress NMI, which can be delivered using the old mapping.

Also on x86_64, idt_invalidate() to clear idt as on 32 bits.

Signed-off-by: Pingfan Liu <kernelfans@...il.com>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Ingo Molnar <mingo@...hat.com>
Cc: Arnaldo Carvalho de Melo <acme@...nel.org>
Cc: Mark Rutland <mark.rutland@....com>
Cc: Alexander Shishkin <alexander.shishkin@...ux.intel.com>
Cc: Jiri Olsa <jolsa@...hat.com>
Cc: Namhyung Kim <namhyung@...nel.org>
Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: Borislav Petkov <bp@...en8.de>
Cc: "H. Peter Anvin" <hpa@...or.com>
Cc: Omar Sandoval <osandov@...com>
Cc: Andrew Morton <akpm@...ux-foundation.org>
Cc: Mike Rapoport <rppt@...nel.org>
To: x86@...nel.org
Cc: linux-kernel@...r.kernel.org
---
 arch/x86/kernel/machine_kexec_32.c | 1 +
 arch/x86/kernel/machine_kexec_64.c | 3 +++
 2 files changed, 4 insertions(+)

diff --git a/arch/x86/kernel/machine_kexec_32.c b/arch/x86/kernel/machine_kexec_32.c
index 64b00b0..72c6100 100644
--- a/arch/x86/kernel/machine_kexec_32.c
+++ b/arch/x86/kernel/machine_kexec_32.c
@@ -191,6 +191,7 @@ void machine_kexec(struct kimage *image)
 	/* Interrupts aren't acceptable while we reboot */
 	local_irq_disable();
 	hw_breakpoint_disable();
+	perf_pmu_disable_all();
 
 	if (image->preserve_context) {
 #ifdef CONFIG_X86_IO_APIC
diff --git a/arch/x86/kernel/machine_kexec_64.c b/arch/x86/kernel/machine_kexec_64.c
index a29a44a..238893e 100644
--- a/arch/x86/kernel/machine_kexec_64.c
+++ b/arch/x86/kernel/machine_kexec_64.c
@@ -17,6 +17,7 @@
 #include <linux/suspend.h>
 #include <linux/vmalloc.h>
 #include <linux/efi.h>
+#include <linux/perf_event.h>
 
 #include <asm/init.h>
 #include <asm/tlbflush.h>
@@ -338,6 +339,8 @@ void machine_kexec(struct kimage *image)
 	/* Interrupts aren't acceptable while we reboot */
 	local_irq_disable();
 	hw_breakpoint_disable();
+	perf_pmu_disable_all();
+	idt_invalidate(phys_to_virt(0));
 
 	if (image->preserve_context) {
 #ifdef CONFIG_X86_IO_APIC
-- 
2.7.5