Re: [PATCH] arch/x86/kernel/cpu/microcode/intel: don't store initrd's start

From	Nicolai Stange <nicstange@gmail.com>
Newsgroups	linux.kernel
Subject	Re: [PATCH] arch/x86/kernel/cpu/microcode/intel: don't store initrd's start
Date	2016-07-25 16:20 +0200
Message-ID	<rYOTF-5Bn-65@gated-at.bofh.it> (permalink)
References	(1 earlier) <rYIbv-1BM-1@gated-at.bofh.it> <rYKmZ-2Pk-3@gated-at.bofh.it> <rYNkR-4yZ-9@gated-at.bofh.it> <rYNEd-4FI-11@gated-at.bofh.it> <rYOqB-5bn-3@gated-at.bofh.it>
Organization	linux.* mail to news gateway

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Borislav Petkov <bp@alien8.de> writes:

> On Mon, Jul 25, 2016 at 02:59:43PM +0200, Nicolai Stange wrote:
>> Applied on top of next-20160722 and it boots
>
> Does it apply the microcode too? Or your box doesn't need microcode?

[    0.000000] microcode: microcode updated early to revision 0x20, date = 2016-03-16
[    2.929972] microcode: sig=0x306c3, pf=0x10, revision=0x20

Is this a "yes"?

/proc/cpuinfo shows a "microcode" value of 0x20 for all logical cores at
least.

>> Doesn't this break the builtin-ucode case (!blobs.valid) where
>> blobs.start is supposed to be zero?
>
> Good point.
>
> Well, it shouldn't because in the builtin case start should simply
> contain the ASLR offset the physmem mapping was moved to and this offset
> is exactly where the builtin images should be... Let me poke at it to
> see whether I'm seeing things correctly.

Hmm. From what I've seen, I've concluded that the builtin images'
addresses are __va ones (assuming x86_64). I might be wrong though.

Another point: does PAGE_OFFSET_BASE exist on ARCH=i386?

And a third one, more of a sidenote: I've seen a comment somewhere that
blobs.start is set to 0 in the builtin case. However, I was unable to
find this initialization in the original code. This very last point
would have been fixed by my patch as a sideeffect. I just forgot about
this remark.

Thanks,

Nicolai

Thread

[PATCH] arch/x86/kernel/cpu/microcode/intel: don't store initrd's start Nicolai Stange <nicstange@gmail.com> - 2016-07-24 17:10 +0200
  Re: [PATCH] arch/x86/kernel/cpu/microcode/intel: don't store  initrd's start Borislav Petkov <bp@alien8.de> - 2016-07-25 09:10 +0200
    Re: [PATCH] arch/x86/kernel/cpu/microcode/intel: don't store initrd's start Nicolai Stange <nicstange@gmail.com> - 2016-07-25 11:30 +0200
      Re: [PATCH] arch/x86/kernel/cpu/microcode/intel: don't store  initrd's start Borislav Petkov <bp@alien8.de> - 2016-07-25 14:40 +0200
        Re: [PATCH] arch/x86/kernel/cpu/microcode/intel: don't store initrd's start Nicolai Stange <nicstange@gmail.com> - 2016-07-25 15:00 +0200
          Re: [PATCH] arch/x86/kernel/cpu/microcode/intel: don't store initrd's start Nicolai Stange <nicstange@gmail.com> - 2016-07-25 15:10 +0200
          Re: [PATCH] arch/x86/kernel/cpu/microcode/intel: don't store  initrd's start Borislav Petkov <bp@alien8.de> - 2016-07-25 15:50 +0200
            Re: [PATCH] arch/x86/kernel/cpu/microcode/intel: don't store initrd's start Nicolai Stange <nicstange@gmail.com> - 2016-07-25 16:20 +0200
              Re: [PATCH] arch/x86/kernel/cpu/microcode/intel: don't store initrd's start Nicolai Stange <nicstange@gmail.com> - 2016-07-25 16:30 +0200
                Re: [PATCH] arch/x86/kernel/cpu/microcode/intel: don't store  initrd's start Borislav Petkov <bp@alien8.de> - 2016-07-25 18:50 +0200
              Re: [PATCH] arch/x86/kernel/cpu/microcode/intel: don't store  initrd's start Borislav Petkov <bp@alien8.de> - 2016-07-25 17:10 +0200
              Re: [PATCH] arch/x86/kernel/cpu/microcode/intel: don't store  initrd's start Borislav Petkov <bp@alien8.de> - 2016-07-25 18:50 +0200
                Re: [PATCH] arch/x86/kernel/cpu/microcode/intel: don't store initrd's start Nicolai Stange <nicstange@gmail.com> - 2016-07-25 19:50 +0200
                Re: [PATCH] arch/x86/kernel/cpu/microcode/intel: don't store  initrd's start Borislav Petkov <bp@alien8.de> - 2016-07-25 20:20 +0200

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