[PATCH v8 8/9] x86/mtrr: Avoid repeated save of MTRRs on boot-time CPU bringup

From: Usama Arif
Date: Thu Feb 09 2023 - 10:43:19 EST


From: David Woodhouse <dwmw@xxxxxxxxxxxx>

There's no need to repeatedly save the BSP's MTRRs for each AP being
brought up at boot time. And no need to use smp_call_function_single()
even for the one time they do need to be saved.

Signed-off-by: David Woodhouse <dwmw@xxxxxxxxxxxx>
Signed-off-by: Usama Arif <usama.arif@xxxxxxxxxxxxx>
---
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 783f3210d582..b6eae3ad4414 100644
--- a/arch/x86/kernel/cpu/mtrr/mtrr.c
+++ b/arch/x86/kernel/cpu/mtrr/mtrr.c
@@ -721,11 +721,20 @@ void __init mtrr_bp_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);
}
--
2.25.1