linux-kernel - Re: [tip:x86/microcode] x86/microcode_intel_early.c: Early update ucode on Intel's CPU

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Message-ID: <CAE9FiQXbBXucvAkDf6O3XFS-6mFDW0U9qKfA8CZbDRpq=e0OrQ@mail.gmail.com>
Date:	Mon, 17 Dec 2012 17:11:40 -0800
From:	Yinghai Lu <yinghai@...nel.org>
To:	"H. Peter Anvin" <hpa@...or.com>,
	Jason Wessel <jason.wessel@...driver.com>
Cc:	"H. Peter Anvin" <hpa@...ux.intel.com>,
	Borislav Petkov <bp@...en8.de>,
	"Yu, Fenghua" <fenghua.yu@...el.com>,
	"mingo@...nel.org" <mingo@...nel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"tglx@...utronix.de" <tglx@...utronix.de>,
	"linux-tip-commits@...r.kernel.org" 
	<linux-tip-commits@...r.kernel.org>,
	Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>,
	Stefano Stabellini <Stefano.Stabellini@...citrix.com>
Subject: Re: [tip:x86/microcode] x86/microcode_intel_early.c: Early update
 ucode on Intel's CPU

On Mon, Dec 17, 2012 at 3:26 PM, Yinghai Lu <yinghai@...nel.org> wrote:
> On Mon, Dec 17, 2012 at 3:11 PM, H. Peter Anvin <hpa@...or.com> wrote:
>> On 12/17/2012 02:47 PM, Yinghai Lu wrote:
>>>
>>>
>>> Peter, can you check that branch again?
>>>
>>> I moved the early_trap_init after init_mem_mapping.
>>> so for 64bit native, init_mem_mapping will setup page table for ram from
>>> blank.
>>>
>>
>> Looks better, at first glance at least.  There are a couple of unnecessary
>> changes (the counter in head_64.S cannot exceed 32 bits once computed, so
>> the change from %rcx to %ecx change is pointless.)
>
> ok,  return to use %ecx
>
>>
>> There is another bug in my patch: it either needs to mask off the NX bit if
>> we are running on non-NX-enabled hardware, or it needs to not set the NX bit
>> (which is mostly okay that early on, I suspect.)
>
> i test that in kvm guest, and westmere, current version seem ok.
>
> will repost the patchset to list to get more review.
>

not sure if i could move that early_trap_init down.

jason,

We need to move down early_trap_init after init_memory_mapping to use
early #PF handler to set page table.

So can we do that? for kgdb it is that ok to move it down?

or can we just move
set_intr_gate(X86_TRAP_PF, &page_fault)
back to trap_init?

Thanks

Yinghai
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