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Subject[tip:x86/mm] x86/mm: Add a 'noinvpcid' boot option to turn off INVPCID
Commit-ID:  d12a72b844a49d4162f24cefdab30bed3f86730e
Gitweb: http://git.kernel.org/tip/d12a72b844a49d4162f24cefdab30bed3f86730e
Author: Andy Lutomirski <luto@kernel.org>
AuthorDate: Fri, 29 Jan 2016 11:42:58 -0800
Committer: Ingo Molnar <mingo@kernel.org>
CommitDate: Tue, 9 Feb 2016 13:36:10 +0100

x86/mm: Add a 'noinvpcid' boot option to turn off INVPCID

This adds a chicken bit to turn off INVPCID in case something goes
wrong. It's an early_param() because we do TLB flushes before we
parse __setup() parameters.

Signed-off-by: Andy Lutomirski <luto@kernel.org>
Reviewed-by: Borislav Petkov <bp@suse.de>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Luis R. Rodriguez <mcgrof@suse.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Toshi Kani <toshi.kani@hp.com>
Cc: linux-mm@kvack.org
Link: http://lkml.kernel.org/r/f586317ed1bc2b87aee652267e515b90051af385.1454096309.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
Documentation/kernel-parameters.txt | 2 ++
arch/x86/kernel/cpu/common.c | 16 ++++++++++++++++
2 files changed, 18 insertions(+)

diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index 551ecf0..e4c4d2a 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -2566,6 +2566,8 @@ bytes respectively. Such letter suffixes can also be entirely omitted.

nointroute [IA-64]

+ noinvpcid [X86] Disable the INVPCID cpu feature.
+
nojitter [IA-64] Disables jitter checking for ITC timers.

no-kvmclock [X86,KVM] Disable paravirtualized KVM clock driver
diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c
index 37830de..f4d0aa6 100644
--- a/arch/x86/kernel/cpu/common.c
+++ b/arch/x86/kernel/cpu/common.c
@@ -162,6 +162,22 @@ static int __init x86_mpx_setup(char *s)
}
__setup("nompx", x86_mpx_setup);

+static int __init x86_noinvpcid_setup(char *s)
+{
+ /* noinvpcid doesn't accept parameters */
+ if (s)
+ return -EINVAL;
+
+ /* do not emit a message if the feature is not present */
+ if (!boot_cpu_has(X86_FEATURE_INVPCID))
+ return 0;
+
+ setup_clear_cpu_cap(X86_FEATURE_INVPCID);
+ pr_info("noinvpcid: INVPCID feature disabled\n");
+ return 0;
+}
+early_param("noinvpcid", x86_noinvpcid_setup);
+
#ifdef CONFIG_X86_32
static int cachesize_override = -1;
static int disable_x86_serial_nr = 1;
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