From: Thomas Gleixner <tglx@linutronix.de>
To: speck@linutronix.de
Subject: Re: BUG: disabling SMT from BIOS
Date: Mon, 30 Jul 2018 23:24:20 +0200 (CEST) [thread overview]
Message-ID: <alpine.DEB.2.21.1807302322500.1725@nanos.tec.linutronix.de> (raw)
In-Reply-To: <20180723151356.7wkmmqksvwqvlgdg@treble>
On Mon, 23 Jul 2018, speck for Josh Poimboeuf wrote:
> From: Josh Poimboeuf <jpoimboe@redhat.com>
> Subject: [PATCH] cpu/hotplug: detect SMT disabled by BIOS
>
> If SMT is disabled in BIOS, the CPU code doesn't properly detect it.
> The /sys/devices/system/cpu/smt/control file shows 'on', and the 'l1tf'
> vulnerabilities file shows SMT as vulnerable.
>
> Fix it by forcing 'cpu_smt_control' to CPU_SMT_NOT_SUPPORTED in such a
> case. Unfortunately the detection can only be done after bringing all
> the CPUs online, so we have to overwrite any previous writes to the
> variable.
Bah, this whole CPU enumeration on x86 sucks.
> Reported-by: Joe Mario <jmario@redhat.com>
> Fixes: f048c399e0f7 ("x86/topology: Provide topology_smt_supported()")
> Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Belated Acked-by-me.
prev parent reply other threads:[~2018-07-30 21:24 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-07-22 22:02 [MODERATED] BUG: disabling SMT from BIOS Josh Poimboeuf
2018-07-23 8:06 ` [MODERATED] " Jiri Kosina
2018-07-23 8:44 ` Peter Zijlstra
2018-07-23 10:15 ` Jiri Kosina
2018-07-23 12:45 ` Josh Poimboeuf
2018-07-23 14:03 ` Jiri Kosina
2018-07-23 15:13 ` Josh Poimboeuf
2018-07-24 7:30 ` Jiri Kosina
2018-07-24 15:36 ` Peter Zijlstra
2018-07-24 16:36 ` Peter Zijlstra
2018-07-24 22:34 ` Peter Zijlstra
2018-07-25 8:45 ` Peter Zijlstra
2018-07-25 10:05 ` Peter Zijlstra
2018-07-25 10:18 ` Greg KH
2018-07-30 21:24 ` Thomas Gleixner [this message]
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