linux-kernel - Re: [Stable-review] [12/28] x86, cpu: Clean up AMD erratum 400 workaround

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Message-ID: <1303263653.3464.65.camel@localhost>
Date:	Wed, 20 Apr 2011 02:40:53 +0100
From:	Ben Hutchings <ben@...adent.org.uk>
To:	Hans Rosenfeld <hans.rosenfeld@....com>
Cc:	linux-kernel@...r.kernel.org, stable@...nel.org,
	akpm@...ux-foundation.org, "H. Peter Anvin" <hpa@...ux.intel.com>,
	torvalds@...ux-foundation.org, stable-review@...nel.org,
	alan@...rguk.ukuu.org.uk, Greg KH <gregkh@...e.de>
Subject: Re: [Stable-review] [12/28] x86, cpu: Clean up AMD erratum 400
 workaround

On Tue, 2011-04-19 at 13:30 -0700, Greg KH wrote:
> 2.6.32-longterm review patch.  If anyone has any objections, please let us know.
> 
> ------------------
> 
> From: Hans Rosenfeld <hans.rosenfeld@....com>
> 
> commit 9d8888c2a214aece2494a49e699a097c2ba9498b upstream.
> 
> Remove check_c1e_idle() and use the new AMD errata checking framework
> instead.

Clean-up patches are generally not candidates for longterm updates.

However, I notice that the range of procesors considered to have erratum
400 was also changed:

[...]
> +const int amd_erratum_400[] =
> +	AMD_OSVW_ERRATUM(1, AMD_MODEL_RANGE(0xf, 0x41, 0x2, 0xff, 0xf),
> +			    AMD_MODEL_RANGE(0x10, 0x2, 0x1, 0xff, 0xf));
[...]
> -	/* Family 0x0f models < rev F do not have C1E */
> -	if (c->x86 == 0x0F && c->x86_model >= 0x40)
> -		return 1;
> -
> -	if (c->x86 == 0x10) {
> -		/*
> -		 * check OSVW bit for CPUs that are not affected
> -		 * by erratum #400
> -		 */
> -		if (cpu_has(c, X86_FEATURE_OSVW)) {
[...]
> -		}
> -		return 1;
[...]

Family 0x0f model 0x40 and model 0x41 stepping 0 and 1 are excluded.
Family 0x10 model 0x00, 0x01 and model 0x02 stepping 0 are excluded.
Is that the real fix here?

Ben.

-- 
Ben Hutchings
Once a job is fouled up, anything done to improve it makes it worse.

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