Commit 777284b6 authored Oct 25, 2016 by Borislav Petkov Committed by Ingo Molnar Oct 25, 2016

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>

parent 9fe68cad

arch/x86/kernel/cpu/common.c

+2 −5

Original line number	Diff line number	Diff line
		@@ -1462,10 +1462,7 @@ void cpu_init(void)
		*/
		cr4_init_shadow();

		/*
		* Load microcode on this cpu if a valid microcode is available.
		* This is early microcode loading procedure.
		*/
		if (cpu)
		load_ucode_ap();

		t = &per_cpu(cpu_tss, cpu);

arch/x86/kernel/cpu/microcode/amd.c

+0 −5

Original line number	Diff line number	Diff line
		@@ -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;