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Subject[PATCH v3 8/9] x86/mtrr: Avoid repeated save of MTRRs on boot-time CPU bringup
Date
From: David Woodhouse <dwmw@amazon.co.uk>

There's no need to repeatedly save the BSP's MTRRs for each AP we bring
up at boot time. And there's no need to use smp_call_function_single()
even for the one time we *do* want to do it.

Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
---
arch/x86/kernel/cpu/mtrr/mtrr.c | 9 +++++++++
1 file changed, 9 insertions(+)

diff --git a/arch/x86/kernel/cpu/mtrr/mtrr.c b/arch/x86/kernel/cpu/mtrr/mtrr.c
index 2746cac9d8a9..2884017586f1 100644
--- a/arch/x86/kernel/cpu/mtrr/mtrr.c
+++ b/arch/x86/kernel/cpu/mtrr/mtrr.c
@@ -814,11 +814,20 @@ void mtrr_ap_init(void)
*/
void mtrr_save_state(void)
{
+ static bool mtrr_saved;
int first_cpu;

if (!mtrr_enabled())
return;

+ if (system_state < SYSTEM_RUNNING) {
+ if (!mtrr_saved) {
+ mtrr_save_fixed_ranges(NULL);
+ mtrr_saved = true;
+ }
+ return;
+ }
+
first_cpu = cpumask_first(cpu_online_mask);
smp_call_function_single(first_cpu, mtrr_save_fixed_ranges, NULL, 1);
}
--
2.31.1
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