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x86/microcode: Run the AP-loading routine only on the application processors 

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>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20161025095522.11964-2-bp@alien8.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Borislav Petkov 2016-10-25 11:55:11 +02:00 committed by Ingo Molnar
parent 9fe68cad6e
commit 777284b66f
2 changed files with 2 additions and 10 deletions
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5
arch/x86/kernel/cpu/common.c
View File

@ -1462,10 +1462,7 @@ void cpu_init(void)
*/ */
cr4_init_shadow(); cr4_init_shadow();
/* if (cpu)
* Load microcode on this cpu if a valid microcode is available.
* This is early microcode loading procedure.
*/
load_ucode_ap(); load_ucode_ap();
t = &per_cpu(cpu_tss, cpu); t = &per_cpu(cpu_tss, cpu);

5
arch/x86/kernel/cpu/microcode/amd.c
View File

@ -357,17 +357,12 @@ static void __init get_bsp_sig(void)
#else #else
void load_ucode_amd_ap(void) void load_ucode_amd_ap(void)
{ {
unsigned int cpu = smp_processor_id();
struct equiv_cpu_entry *eq; struct equiv_cpu_entry *eq;
struct microcode_amd *mc; struct microcode_amd *mc;
u8 *cont = container; u8 *cont = container;
u32 rev, eax; u32 rev, eax;
u16 eq_id; u16 eq_id;
/* Exit if called on the BSP. */
if (!cpu)
return;
if (!container) if (!container)
return; return;