From: tip-bot for Thomas Gleixner <tipbot@zytor.com>
To: linux-tip-commits@vger.kernel.org
Cc: michael.h.kelley@microsoft.com, jkosina@suse.cz,
linux-kernel@vger.kernel.org, luto@kernel.org, riel@surriel.com,
kys@microsoft.com, mingo@kernel.org, mojha@codeaurora.org,
Tianyu.Lan@microsoft.com, peterz@infradead.org, hpa@zytor.com,
jpoimboe@redhat.com, tglx@linutronix.de,
torvalds@linux-foundation.org, bp@alien8.de,
konrad.wilk@oracle.com, gregkh@linuxfoundation.org
Subject: [tip:smp/urgent] x86/smp: Enforce CONFIG_HOTPLUG_CPU when SMP=y
Date: Thu, 28 Mar 2019 05:39:18 -0700 [thread overview]
Message-ID: <tip-bebd024e4815b1a170fcd21ead9c2222b23ce9e6@git.kernel.org> (raw)
In-Reply-To: <20190326163811.598166056@linutronix.de>
Commit-ID: bebd024e4815b1a170fcd21ead9c2222b23ce9e6
Gitweb: https://git.kernel.org/tip/bebd024e4815b1a170fcd21ead9c2222b23ce9e6
Author: Thomas Gleixner <tglx@linutronix.de>
AuthorDate: Tue, 26 Mar 2019 17:36:06 +0100
Committer: Thomas Gleixner <tglx@linutronix.de>
CommitDate: Thu, 28 Mar 2019 13:34:58 +0100
x86/smp: Enforce CONFIG_HOTPLUG_CPU when SMP=y
The SMT disable 'nosmt' command line argument is not working properly when
CONFIG_HOTPLUG_CPU is disabled. The teardown of the sibling CPUs which are
required to be brought up due to the MCE issues, cannot work. The CPUs are
then kept in a half dead state.
As the 'nosmt' functionality has become popular due to the speculative
hardware vulnerabilities, the half torn down state is not a proper solution
to the problem.
Enforce CONFIG_HOTPLUG_CPU=y when SMP is enabled so the full operation is
possible.
Reported-by: Tianyu Lan <Tianyu.Lan@microsoft.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Konrad Wilk <konrad.wilk@oracle.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Mukesh Ojha <mojha@codeaurora.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Jiri Kosina <jkosina@suse.cz>
Cc: Rik van Riel <riel@surriel.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Micheal Kelley <michael.h.kelley@microsoft.com>
Cc: "K. Y. Srinivasan" <kys@microsoft.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: K. Y. Srinivasan <kys@microsoft.com>
Cc: stable@vger.kernel.org
Link: https://lkml.kernel.org/r/20190326163811.598166056@linutronix.de
---
arch/x86/Kconfig | 8 +-------
1 file changed, 1 insertion(+), 7 deletions(-)
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index c1f9b3cf437c..5ad92419be19 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -2217,14 +2217,8 @@ config RANDOMIZE_MEMORY_PHYSICAL_PADDING
If unsure, leave at the default value.
config HOTPLUG_CPU
- bool "Support for hot-pluggable CPUs"
+ def_bool y
depends on SMP
- ---help---
- Say Y here to allow turning CPUs off and on. CPUs can be
- controlled through /sys/devices/system/cpu.
- ( Note: power management support will enable this option
- automatically on SMP systems. )
- Say N if you want to disable CPU hotplug.
config BOOTPARAM_HOTPLUG_CPU0
bool "Set default setting of cpu0_hotpluggable"
prev parent reply other threads:[~2019-03-28 12:40 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-03-26 16:36 [patch 0/2] cpu/hotplug: Prevent damage with SMP=y and HOTPLUG_CPU=n Thomas Gleixner
2019-03-26 16:36 ` [patch 1/2] cpu/hotplug: Prevent crash when CPU bringup fails on CONFIG_HOTPLUG_CPU=n Thomas Gleixner
2019-03-27 1:12 ` Greg KH
2019-03-28 12:38 ` [tip:smp/urgent] " tip-bot for Thomas Gleixner
2019-03-26 16:36 ` [patch 2/2] x86/smp: Enforce CONFIG_HOTPLUG_CPU when SMP=y Thomas Gleixner
2019-03-27 1:12 ` Greg KH
2019-03-28 12:39 ` tip-bot for Thomas Gleixner [this message]
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