From: Andy Lutomirski luto@kernel.org
commit 0790c9aad84901ca1bdc14746175549c8b5da215 upstream.
The parameter is only present on x86_64 systems to save a few bytes, as PCID is always disabled on x86_32.
Signed-off-by: Andy Lutomirski luto@kernel.org Reviewed-by: Nadav Amit nadav.amit@gmail.com Reviewed-by: Borislav Petkov bp@suse.de Reviewed-by: Thomas Gleixner tglx@linutronix.de Cc: Andrew Morton akpm@linux-foundation.org Cc: Arjan van de Ven arjan@linux.intel.com Cc: Borislav Petkov bp@alien8.de Cc: Dave Hansen dave.hansen@intel.com Cc: Linus Torvalds torvalds@linux-foundation.org Cc: Mel Gorman mgorman@suse.de Cc: Peter Zijlstra peterz@infradead.org Cc: Rik van Riel riel@redhat.com Cc: linux-mm@kvack.org Link: http://lkml.kernel.org/r/8bbb2e65bcd249a5f18bfb8128b4689f08ac2b60.1498751203... Signed-off-by: Ingo Molnar mingo@kernel.org Cc: Hugh Dickins hughd@google.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
(cherry picked from commit dcccd3c266e24ce80ecf592765315c54c222ac33) Signed-off-by: Pavel Tatashin pasha.tatashin@oracle.com --- Documentation/kernel-parameters.txt | 2 ++ arch/x86/kernel/cpu/common.c | 18 ++++++++++++++++++ 2 files changed, 20 insertions(+)
diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt index ceaab09a279e..97bc24101896 100644 --- a/Documentation/kernel-parameters.txt +++ b/Documentation/kernel-parameters.txt @@ -2471,6 +2471,8 @@ bytes respectively. Such letter suffixes can also be entirely omitted. nopat [X86] Disable PAT (page attribute table extension of pagetables) support.
+ nopcid [X86-64] Disable the PCID cpu feature. + norandmaps Don't use address space randomization. Equivalent to echo 0 > /proc/sys/kernel/randomize_va_space
diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c index 90ef802d9d90..843be1de5ddb 100644 --- a/arch/x86/kernel/cpu/common.c +++ b/arch/x86/kernel/cpu/common.c @@ -172,6 +172,24 @@ static int __init x86_xsaves_setup(char *s) } __setup("noxsaves", x86_xsaves_setup);
+#ifdef CONFIG_X86_64 +static int __init x86_pcid_setup(char *s) +{ + /* require an exact match without trailing characters */ + if (strlen(s)) + return 0; + + /* do not emit a message if the feature is not present */ + if (!boot_cpu_has(X86_FEATURE_PCID)) + return 1; + + setup_clear_cpu_cap(X86_FEATURE_PCID); + pr_info("nopcid: PCID feature disabled\n"); + return 1; +} +__setup("nopcid", x86_pcid_setup); +#endif + static int __init x86_noinvpcid_setup(char *s) { /* noinvpcid doesn't accept parameters */