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Groups > linux.kernel > #1508142

[PATCH 01/12] x86/microcode: Run the AP-loading routine only on the application processors

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From: Borislav Petkov <bp@suse.de>

cpu_init() is run also on the BSP (in addition to the APs):

x86_64_start_kernel
|-> x86_64_start_reservations
|-> start_kernel
|-> trap_init
|-> cpu_init
|-> load_ucode_ap
...

but we run the AP (Application Processors) microcode loading routine
there too even though we have a BSP-specific routine for that:
load_ucode_bsp().

Which is unnecessary. So let's limit the AP microcode loading routine to
the APs only.

Remove a useless comment while at it.

Signed-off-by: Borislav Petkov <bp@suse.de>
---
 arch/x86/kernel/cpu/common.c        | 7 ++-----
 arch/x86/kernel/cpu/microcode/amd.c | 5 -----
 2 files changed, 2 insertions(+), 10 deletions(-)

diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c
index 9bd910a7dd0a..1a1d668263b9 100644
--- a/arch/x86/kernel/cpu/common.c
+++ b/arch/x86/kernel/cpu/common.c
@@ -1462,11 +1462,8 @@ void cpu_init(void)
 	 */
 	cr4_init_shadow();
 
-	/*
-	 * Load microcode on this cpu if a valid microcode is available.
-	 * This is early microcode loading procedure.
-	 */
-	load_ucode_ap();
+	if (cpu)
+		load_ucode_ap();
 
 	t = &per_cpu(cpu_tss, cpu);
 	oist = &per_cpu(orig_ist, cpu);
diff --git a/arch/x86/kernel/cpu/microcode/amd.c b/arch/x86/kernel/cpu/microcode/amd.c
index 620ab06bcf45..6b3929e80fd4 100644
--- a/arch/x86/kernel/cpu/microcode/amd.c
+++ b/arch/x86/kernel/cpu/microcode/amd.c
@@ -357,17 +357,12 @@ static void __init get_bsp_sig(void)
 #else
 void load_ucode_amd_ap(void)
 {
-	unsigned int cpu = smp_processor_id();
 	struct equiv_cpu_entry *eq;
 	struct microcode_amd *mc;
 	u8 *cont = container;
 	u32 rev, eax;
 	u16 eq_id;
 
-	/* Exit if called on the BSP. */
-	if (!cpu)
-		return;
-
 	if (!container)
 		return;
 
-- 
2.10.0

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[PATCH 00/12] x86/microcode: Rework microcode loading Borislav Petkov <bp@alien8.de> - 2016-10-25 12:00 +0200
  [PATCH 07/12] x86/microcode: Issue the debug printk on resume only on success Borislav Petkov <bp@alien8.de> - 2016-10-25 12:00 +0200
    [tip:x86/microcode] x86/microcode: Issue the debug printk on resume  only on success tip-bot for Borislav Petkov <tipbot@zytor.com> - 2016-10-25 18:40 +0200
  [PATCH 01/12] x86/microcode: Run the AP-loading routine only on the application processors Borislav Petkov <bp@alien8.de> - 2016-10-25 12:00 +0200
    [tip:x86/microcode] x86/microcode: Run the AP-loading routine only  on the application processors tip-bot for Borislav Petkov <tipbot@zytor.com> - 2016-10-25 18:30 +0200
  [PATCH 09/12] x86/microcode/AMD: Retract functions Borislav Petkov <bp@alien8.de> - 2016-10-25 12:00 +0200
    [tip:x86/microcode] x86/microcode/amd: Move private inlines to .c  and mark local functions static tip-bot for Borislav Petkov <tipbot@zytor.com> - 2016-10-25 18:40 +0200
  [PATCH 08/12] x86/microcode: Collect CPU info on resume Borislav Petkov <bp@alien8.de> - 2016-10-25 12:00 +0200
    [tip:x86/microcode] x86/microcode: Collect CPU info on resume tip-bot for Borislav Petkov <tipbot@zytor.com> - 2016-10-25 18:40 +0200
  [PATCH 10/12] x86/microcode/intel: Remove intel_lib.c Borislav Petkov <bp@alien8.de> - 2016-10-25 12:00 +0200
    [tip:x86/microcode] x86/microcode/intel: Remove intel_lib.c tip-bot for Borislav Petkov <tipbot@zytor.com> - 2016-10-25 18:40 +0200
  [PATCH 06/12] x86/microcode/AMD: Hand down the CPU family Borislav Petkov <bp@alien8.de> - 2016-10-25 12:00 +0200
    [tip:x86/microcode] x86/microcode/amd: Hand down the CPU family tip-bot for Borislav Petkov <tipbot@zytor.com> - 2016-10-25 18:40 +0200
  [PATCH 02/12] x86/microcode: Move driver authors to CREDITS Borislav Petkov <bp@alien8.de> - 2016-10-25 12:00 +0200
    [tip:x86/microcode] x86/microcode: Move driver authors to CREDITS tip-bot for Borislav Petkov <tipbot@zytor.com> - 2016-10-25 18:40 +0200

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