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