linux-kernel - patch "x86: MOVE PCI IO ECS code to x86/pci" breaks CPU hotplug

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Message-Id: <48AD82D5.76E4.0078.0@novell.com>
Date:	Thu, 21 Aug 2008 13:59:33 +0100
From:	"Jan Beulich" <jbeulich@...ell.com>
To:	<robert.richter@....com>, "Ingo Molnar" <mingo@...e.hu>
Cc:	<linux-kernel@...r.kernel.org>
Subject: patch "x86: MOVE PCI IO ECS code to x86/pci" breaks CPU
	hotplug

>Converting __cpuinit functions called out of init_amd() (and similar others)
>to __init (and making them subject of xxx_initcall() handling isn't valid, as
>they would no longer be called for hot plugged CPUs.
>
>Further, since it's likely that in virtualized environments the MSR write
>would at best be ignored, I'd also recommend using the fault-safe
>accessors here *and* check that the bit actually got set before setting
>PCI_HAS_IO_ECS (one would obviously have to BUG() when hot-plugged
>CPUs fail to set the bit when those available at boot successfully did so).

Even worse - this would even try to access the MSR on non-AMD CPUs
(currently probably prevented just by the fact that only AMD ones use
family values of 0x10 or higher).

Jan

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