linux-kernel - Re: AMD microcode loading broken on 32 bit

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Message-ID: <20140128232219.GO815@pd.tnic>
Date:	Wed, 29 Jan 2014 00:22:19 +0100
From:	Borislav Petkov <bp@...en8.de>
To:	Boris Ostrovsky <boris.ostrovsky@...cle.com>
Cc:	"H. Peter Anvin" <hpa@...or.com>, linux-kernel@...r.kernel.org,
	Ingo Molnar <mingo@...nel.org>
Subject: Re: AMD microcode loading broken on 32 bit

On Tue, Jan 28, 2014 at 06:10:59PM -0500, Boris Ostrovsky wrote:
> The patch seems to have fixed the problem.

Thanks, I'll add your Reported-and-tested-by.

>> I'll give it a spin. Apparently the problem is currently in
>> install_equiv_cpu_table() when we are trying to index into buf and
>> buf (which is container) doesn't appear to be there.

Yes.

> >Are you sure that
> >
> >    container = (u8 *)(__va((u32)relocated_ramdisk) +
> >                           ((u32)container -
> >boot_params.hdr.ramdisk_image));
> >
> >in save_microcode_in_initrd_amd() always results in a valid
> >pointer? It is non-NULL but it
> >points to address that looks to be not mapped.

Well, we unconditionally relocate the ramdisk to direct-mapped memory,
see relocate_initrd(). I'll take a look at this tomorrow though, it is
late here.

The good thing is, I can reproduce the initial crash you reported in
qemu+kvm which makes everything very easy to play with. :)

-- 
Regards/Gruss,
    Boris.

Sent from a fat crate under my desk. Formatting is fine.
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