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From: Andy Lutomirski <luto@kernel.org>
To: x86@kernel.org, linux-kernel@vger.kernel.org
Cc: Borislav Petkov <bp@alien8.de>, Brian Gerst <brgerst@gmail.com>,
	Dave Hansen <dave.hansen@linux.intel.com>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	Oleg Nesterov <oleg@redhat.com>,
	"linux-mm@kvack.org" <linux-mm@kvack.org>,
	Andrey Ryabinin <aryabinin@virtuozzo.com>,
	Andy Lutomirski <luto@kernel.org>
Subject: [PATCH v3 2/3] x86/mm: Add a noinvpcid option to turn off INVPCID
Date: Fri, 29 Jan 2016 11:42:58 -0800
Message-ID: <f586317ed1bc2b87aee652267e515b90051af385.1454096309.git.luto@kernel.org> (raw)
In-Reply-To: <cover.1454096309.git.luto@kernel.org>
In-Reply-To: <cover.1454096309.git.luto@kernel.org>

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>
---
 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 742f69d18fc8..b34e55e00bae 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -2508,6 +2508,8 @@ 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 c2b7522cbf35..48196980c1c7 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;
-- 
2.5.0

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  parent reply index

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-01-29 19:42 [PATCH v3 0/3] x86/mm: INVPCID support Andy Lutomirski
2016-01-29 19:42 ` [PATCH v3 1/3] x86/mm: Add INVPCID helpers Andy Lutomirski
2016-01-29 19:42 ` Andy Lutomirski [this message]
2016-01-29 19:42 ` [PATCH v3 3/3] x86/mm: If INVPCID is available, use it to flush global mappings Andy Lutomirski
2016-02-01 10:51 ` [PATCH v3 0/3] x86/mm: INVPCID support Borislav Petkov

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