[v3,8/9] x86/mtrr: Avoid repeated save of MTRRs on boot-time CPU bringup

Commit Message

David Woodhouse Dec. 15, 2021, 2:56 p.m. UTC

From: David Woodhouse <[e-mail]>

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 <[e-mail]>
---
 arch/x86/kernel/cpu/mtrr/mtrr.c | 9 +++++++++
 1 file changed, 9 insertions(+)

Patch

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);
 }