From: Fenghua Yu <fenghua.yu@intel.com>
To: "Thomas Gleixner" <tglx@linutronix.de>,
"Ingo Molnar" <mingo@redhat.com>, "H Peter Anvin" <hpa@zytor.com>
Cc: "Ashok Raj" <ashok.raj@intel.com>,
"Alan Cox" <alan@linux.intel.com>,
"Dave Hansen" <dave.hansen@intel.com>,
"Peter Zijlstra" <peterz@infradead.org>,
"Rafael Wysocki" <rafael.j.wysocki@intel.com>,
"Tony Luck" <tony.luck@intel.com>,
"Ravi V Shankar" <ravi.v.shankar@intel.com>,
"linux-kernel" <linux-kernel@vger.kernel.org>,
"x86" <x86@kernel.org>, Fenghua Yu <fenghua.yu@intel.com>
Subject: [PATCH v2 4/4] x86/split_lock: Disable #AC for split locked accesses
Date: Fri, 29 Jun 2018 07:33:27 -0700 [thread overview]
Message-ID: <1530282807-66555-5-git-send-email-fenghua.yu@intel.com> (raw)
In-Reply-To: <1530282807-66555-1-git-send-email-fenghua.yu@intel.com>
By default, #AC for split lock is enabled. In some cases (e.g. system
hang when firmware hits split lock), user may want to opt-out of the
feature.
Kernel parameter "ac_split_lock_off" disables the feature during boot time.
Signed-off-by: Fenghua Yu <fenghua.yu@intel.com>
---
Documentation/admin-guide/kernel-parameters.txt | 4 ++++
arch/x86/kernel/cpu/test_ctl.c | 9 +++++++++
2 files changed, 13 insertions(+)
diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index efc7aa7a0670..7bf3b37dccdb 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -4086,6 +4086,10 @@
spia_pedr=
spia_peddr=
+ ac_split_lock_off [X86]
+ Disable #AC exception for split locked accesses.
+ By default, this feature is enabled in kernel.
+
srcutree.counter_wrap_check [KNL]
Specifies how frequently to check for
grace-period sequence counter wrap for the
diff --git a/arch/x86/kernel/cpu/test_ctl.c b/arch/x86/kernel/cpu/test_ctl.c
index f12e8b24215d..4e6ed267e8b7 100644
--- a/arch/x86/kernel/cpu/test_ctl.c
+++ b/arch/x86/kernel/cpu/test_ctl.c
@@ -85,3 +85,12 @@ void setup_ac_split_lock(void)
pr_info_once("#AC for split lock is disabled\n");
}
}
+
+static __init int ac_split_lock_off(char *str)
+{
+ enable_ac_split_lock = false;
+
+ return 0;
+}
+
+early_param("ac_split_lock_off", ac_split_lock_off);
--
2.5.0
next prev parent reply other threads:[~2018-06-29 14:34 UTC|newest]
Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-06-29 14:33 [PATCH v2 0/4] x86/split_lock: Enable #AC exception for split locked accesses Fenghua Yu
2018-06-29 14:33 ` [PATCH v2 1/4] x86/split_lock: Enumerate #AC exception for split locked access feature Fenghua Yu
2018-06-29 14:56 ` Dave Hansen
2018-06-29 16:23 ` Thomas Gleixner
2018-06-29 16:32 ` Dave Hansen
2018-07-04 20:07 ` Eduardo Habkost
2018-07-10 18:45 ` Fenghua Yu
2018-07-10 18:54 ` Dave Hansen
2018-07-10 19:47 ` Thomas Gleixner
2018-07-11 19:59 ` Dave Hansen
2018-07-12 20:00 ` Thomas Gleixner
2018-06-29 14:33 ` [PATCH v2 2/4] x86/split_lock: Align x86_capability to unsigned long to avoid split locked access Fenghua Yu
2018-06-29 16:04 ` Dave Hansen
2018-06-29 16:35 ` Thomas Gleixner
2018-06-29 19:03 ` Fenghua Yu
2018-06-29 20:08 ` Thomas Gleixner
2018-06-29 20:38 ` Fenghua Yu
2018-06-29 20:48 ` Dave Hansen
2018-06-29 21:10 ` Fenghua Yu
2018-06-29 21:44 ` Thomas Gleixner
2018-06-30 0:00 ` Fenghua Yu
2018-06-30 0:14 ` Fenghua Yu
2018-06-30 6:23 ` Thomas Gleixner
2018-07-02 12:18 ` Peter Zijlstra
2018-07-02 14:11 ` Fenghua Yu
2018-06-29 14:33 ` [PATCH v2 3/4] x86/split_lock: Handle #AC exception for split lock Fenghua Yu
2018-06-29 16:29 ` Dave Hansen
2018-06-29 16:33 ` Luck, Tony
2018-06-29 17:16 ` Fenghua Yu
2018-06-29 17:29 ` Dave Hansen
2018-06-29 17:39 ` Fenghua Yu
2018-06-29 17:47 ` Dave Hansen
2018-06-29 14:33 ` Fenghua Yu [this message]
2018-06-29 16:31 ` [PATCH v2 4/4] x86/split_lock: Disable #AC for split locked accesses Dave Hansen
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=1530282807-66555-5-git-send-email-fenghua.yu@intel.com \
--to=fenghua.yu@intel.com \
--cc=alan@linux.intel.com \
--cc=ashok.raj@intel.com \
--cc=dave.hansen@intel.com \
--cc=hpa@zytor.com \
--cc=linux-kernel@vger.kernel.org \
--cc=mingo@redhat.com \
--cc=peterz@infradead.org \
--cc=rafael.j.wysocki@intel.com \
--cc=ravi.v.shankar@intel.com \
--cc=tglx@linutronix.de \
--cc=tony.luck@intel.com \
--cc=x86@kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).