From: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
To: Borislav Petkov <bp@suse.de>
Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>,
x86@kernel.org, gregkh@linuxfoundation.org,
david.vrabel@citrix.com, stable@vger.kernel.org,
rshendershot@mchsi.com, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 3.17 100/141] x86, microcode: Fix accessing dis_ucode_ldr on 32-bit
Date: Thu, 27 Nov 2014 11:21:19 -0500 [thread overview]
Message-ID: <20141127162118.GA24829@konrad-lan.dumpdata.com> (raw)
In-Reply-To: <20141127091228.GA4828@pd.tnic>
On Thu, Nov 27, 2014 at 10:12:28AM +0100, Borislav Petkov wrote:
> On Wed, Nov 26, 2014 at 07:13:02PM -0800, Boris Ostrovsky wrote:
> > I was confusing you: accessing dis_ucode_ldr by virtual address does
> > work on PV. But we then fail later, in load_ucode_intel_ap(), because
> > it also tries to use __pa_nodebug() which can't be used by PV.
> >
> > So if accessing dis_ucode_ldr by virtual address is acceptable
> > (although I don't think it is?) then we can stick dis_ucode_ldr=1 into
> > xen_start_kernel() and then things look OK.
> >
> > A better solution may be to replace cpuid in x86_guest() with 'return
> > pv_info.paravirt_enabled' (or paravirt_enabled(), I guess). I gave
> > it a quick spin (32-bit only) and it seems to work. I'll see how my
> > overnight tests behave.
>
> Ok, but let's have a clean design: maybe have a weak default stub which
> returns false when PARAVIRT is not enabled in the .config and then add
> an override in, say, arch/x86/kernel/paravirt.c which returns true when
> running as a guest. Something like that, at least.
You are describing 'paravirt_enabled()' :-)
>
> I can imagine other stuff wanting to use the dynamic checking at runtime
> too...
>
> --
> Regards/Gruss,
> Boris.
>
> Sent from a fat crate under my desk. Formatting is fine.
> --
next prev parent reply other threads:[~2014-11-27 16:21 UTC|newest]
Thread overview: 29+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-11-27 3:13 [PATCH 3.17 100/141] x86, microcode: Fix accessing dis_ucode_ldr on 32-bit Boris Ostrovsky
2014-11-27 9:12 ` Borislav Petkov
2014-11-27 16:21 ` Konrad Rzeszutek Wilk [this message]
2014-11-27 16:36 ` Borislav Petkov
-- strict thread matches above, loose matches on Subject: below --
2014-11-27 23:33 Boris Ostrovsky
2014-11-27 17:14 Boris Ostrovsky
2014-11-27 17:20 ` Borislav Petkov
2014-11-19 20:50 [PATCH 3.17 000/141] 3.17.4-stable review Greg Kroah-Hartman
2014-11-19 20:52 ` [PATCH 3.17 100/141] x86, microcode: Fix accessing dis_ucode_ldr on 32-bit Greg Kroah-Hartman
2014-11-25 18:12 ` Boris Ostrovsky
2014-11-25 18:24 ` Borislav Petkov
2014-11-25 18:43 ` Boris Ostrovsky
2014-11-25 18:43 ` Borislav Petkov
2014-11-25 18:55 ` Boris Ostrovsky
2014-11-25 19:03 ` Borislav Petkov
2014-11-25 19:23 ` Boris Ostrovsky
2014-11-25 19:08 ` Borislav Petkov
2014-11-25 19:28 ` Boris Ostrovsky
2014-11-25 20:26 ` Borislav Petkov
2014-11-25 20:36 ` Konrad Rzeszutek Wilk
2014-11-25 21:17 ` Borislav Petkov
2014-11-25 21:59 ` Boris Ostrovsky
2014-11-25 22:18 ` Borislav Petkov
2014-11-26 5:00 ` Boris Ostrovsky
2014-11-26 10:55 ` Borislav Petkov
2014-11-26 12:39 ` boris ostrovsky
2014-11-26 14:44 ` Borislav Petkov
2014-11-25 18:45 ` Greg Kroah-Hartman
2014-11-25 18:47 ` Borislav Petkov
2014-11-25 18:50 ` Boris Ostrovsky
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