linux-kernel - Re: [PATCH v3 08/10] x86/head64.c: Early update ucode in 64-bit

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Date:	Sun, 16 Dec 2012 13:43:51 -0800
From:	"H. Peter Anvin" <hpa@...or.com>
To:	Yinghai Lu <yinghai@...nel.org>
CC:	Fenghua Yu <fenghua.yu@...el.com>, Ingo Molnar <mingo@...e.hu>,
	Thomas Gleixner <tglx@...utronix.de>,
	Asit K Mallick <asit.k.mallick@...el.com>,
	Tigran Aivazian <tigran@...azian.fsnet.co.uk>,
	Andreas Herrmann <andreas.herrmann3@....com>,
	Borislav Petkov <borislav.petkov@....com>,
	linux-kernel <linux-kernel@...r.kernel.org>, x86 <x86@...nel.org>
Subject: Re: [PATCH v3 08/10] x86/head64.c: Early update ucode in 64-bit

On 12/16/2012 09:59 AM, Yinghai Lu wrote:
>> diff --git a/arch/x86/kernel/head64.c b/arch/x86/kernel/head64.c
>> index 037df57..a512f56 100644
>> --- a/arch/x86/kernel/head64.c
>> +++ b/arch/x86/kernel/head64.c
>> @@ -25,6 +25,7 @@
>>  #include <asm/kdebug.h>
>>  #include <asm/e820.h>
>>  #include <asm/bios_ebda.h>
>> +#include <asm/microcode.h>
>>
>>  static void __init zap_identity_mappings(void)
>>  {
>> @@ -73,6 +74,11 @@ void __init x86_64_start_kernel(char * real_mode_data)
>>         /* clear bss before set_intr_gate with early_idt_handler */
>>         clear_bss();
>>
>> +       /*
>> +        * Load microcode early on BSP.
>> +        */
>> +       load_ucode_bsp(real_mode_data);
>> +
>>         /* Make NULL pointers segfault */
>>         zap_identity_mappings();
>>
> 
> So this patchset is after #PF handler set early page table version?
> 
> then load_ucode_bsp() should be after
> 
>    load_idt((const struct desc_ptr *)&idt_descr);
> 

This patchset isn't before the #PF handler version (you can tell because
it has zap_identity_mappings()), but it does make sense to load the IDT
first.

	-hpa


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