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

commit d12a72b844a49d4162f24cefdab30bed3f86730e upstream.

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>
Cc: Hugh Dickins <hughd@google.com>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index 356bf4b..b71a8ea 100644 (file)
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -1799,6 +1799,8 @@ 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 83df01d..1477e70 100644 (file)
--- a/arch/x86/kernel/cpu/common.c
+++ b/arch/x86/kernel/cpu/common.c
@@ -155,6 +155,22 @@ static int __init x86_xsaveopt_setup(char *s)
 }
 __setup("noxsaveopt", x86_xsaveopt_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 __cpuinitdata = -1;
 static int disable_x86_serial_nr __cpuinitdata = 1;