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From: Borislav Petkov <bp@alien8.de>
To: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: x86@kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] x86/microcode: Adjust ramdisk address when accessing by virtual address
Date: Tue, 20 Dec 2016 00:32:29 +0100	[thread overview]
Message-ID: <20161219233229.p5uw2thbl55o26ds@pd.tnic> (raw)
In-Reply-To: <20161219184340.4tzv2hg2vf3n63b7@pd.tnic>

On Mon, Dec 19, 2016 at 07:43:40PM +0100, Borislav Petkov wrote:
> On Mon, Dec 19, 2016 at 01:12:25PM -0500, Boris Ostrovsky wrote:
> > IIUIC find_microcode_in_initrd() is called with paging on only on Intel
> > (which is where I observed it).
> 
> Ah, that was an important fact. Yes, I can repro it now.

Ok, questions:

* does your guest relocate the ramdisk?

I.e., do you see something like this in dmesg before the splat:

[    0.000000] RAMDISK: [mem 0x7f84c000-0x7ffcffff]
[    0.000000] Allocated new RAMDISK: [mem 0x3647a000-0x36bfd9e6]
[    0.000000] Move RAMDISK from [mem 0x7f84c000-0x7ffcf9e6] to [mem 0x3647a000-0x36bfd9e6]
	       ^^^^^^^^^^^^^^

If not, then I know what happens.

Also, does it work if you change these lines:

        if (!use_pa && relocated_ramdisk)
                start = initrd_start;

to:

        if (!use_pa)
                start = initrd_start;


Because if that works, I can actually simplify that function radically.

But more tomorrow.

Thanks.

-- 
Regards/Gruss,
    Boris.

Good mailing practices for 400: avoid top-posting and trim the reply.

  reply	other threads:[~2016-12-19 23:32 UTC|newest]

Thread overview: 16+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-12-19 15:32 Boris Ostrovsky
2016-12-19 15:37 ` Borislav Petkov
2016-12-19 16:10   ` Boris Ostrovsky
2016-12-19 16:40     ` Borislav Petkov
2016-12-19 18:07       ` Borislav Petkov
2016-12-19 18:12         ` Boris Ostrovsky
2016-12-19 18:43           ` Borislav Petkov
2016-12-19 23:32             ` Borislav Petkov [this message]
2016-12-20  1:27               ` Boris Ostrovsky
2016-12-20  1:40                 ` Boris Ostrovsky
2016-12-20 14:40                   ` Borislav Petkov
2016-12-20 19:26                     ` Boris Ostrovsky
2016-12-20 19:31                       ` Borislav Petkov
2016-12-20 22:48                         ` Boris Ostrovsky
2016-12-20 22:55                           ` Borislav Petkov
2016-12-21  9:55                     ` [tip:x86/urgent] x86/microcode/AMD: Reload proper initrd start address tip-bot for Borislav Petkov

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