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Subject[PATCH][RFC] x86: override prefer_mwait_c1_over_halt to avoid loading cpuidle-haltpoll driver
Date
From: Li RongQing <lirongqing@baidu.com>

x86 KVM guests with MWAIT can load cpuidle-haltpoll driver, and will
cause performance degradation, so override prefer_mwait_c1_over_halt
to a new value, aviod loading cpuidle-haltpoll driver

Signed-off-by: Li RongQing <lirongqing@baidu.com>
---
arch/x86/include/asm/processor.h | 2 +-
arch/x86/kernel/process.c | 1 +
2 files changed, 2 insertions(+), 1 deletion(-)

diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h
index 67c9d73..6bc94fd 100644
--- a/arch/x86/include/asm/processor.h
+++ b/arch/x86/include/asm/processor.h
@@ -658,7 +658,7 @@ extern void amd_e400_c1e_apic_setup(void);
extern unsigned long boot_option_idle_override;

enum idle_boot_override {IDLE_NO_OVERRIDE=0, IDLE_HALT, IDLE_NOMWAIT,
- IDLE_POLL};
+ IDLE_POLL, IDLE_PREF_MWAIT};

extern void enable_sep_cpu(void);
extern int sysenter_setup(void);
diff --git a/arch/x86/kernel/process.c b/arch/x86/kernel/process.c
index c21b734..a16985c 100644
--- a/arch/x86/kernel/process.c
+++ b/arch/x86/kernel/process.c
@@ -889,6 +889,7 @@ void select_idle_routine(const struct cpuinfo_x86 *c)
} else if (prefer_mwait_c1_over_halt(c)) {
pr_info("using mwait in idle threads\n");
x86_idle = mwait_idle;
+ boot_option_idle_override = IDLE_PREF_MWAIT;
} else if (cpu_feature_enabled(X86_FEATURE_TDX_GUEST)) {
pr_info("using TDX aware idle routine\n");
x86_idle = tdx_safe_halt;
--
2.9.4
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