linux-kernel - Re: [PATCH 3/4] x86, head_32: Remove second CPUID detection from default

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Message-ID: <20130211171541.GD2683@pd.tnic>
Date:	Mon, 11 Feb 2013 18:15:41 +0100
From:	Borislav Petkov <bp@...en8.de>
To:	"H. Peter Anvin" <hpa@...or.com>
Cc:	X86 ML <x86@...nel.org>, LKML <linux-kernel@...r.kernel.org>,
	Borislav Petkov <bp@...e.de>
Subject: Re: [PATCH 3/4] x86, head_32: Remove second CPUID detection from
 default_entry

On Mon, Feb 11, 2013 at 07:49:14AM -0800, H. Peter Anvin wrote:
> What about CPUs with inconsistent cpuid levels? Yes, they can and do
> happen, as we discussed on IRC.

Yes, this should still work. We're doing the EFLAGS.ID dance right at
the beginning of default_entry on each cpu and cache cpuld level in
new_cpu_data for the time we're in this code.

What this particular patch removes is the yet-another EFLAGS.ID dance
which we IMHO unnecessarily did after enabling paging.

So basically nothing changes wrt handling inconsistent cpuid levels and
MSR mis-programming - we still should be taking care of those cases.

Thanks.

-- 
Regards/Gruss,
    Boris.

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