4.4-stable review patch. If anyone has any objections, please let me know.
------------------ From: Andy Lutomirski <l...@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 <l...@kernel.org> Reviewed-by: Nadav Amit <nadav.a...@gmail.com> Reviewed-by: Borislav Petkov <b...@suse.de> Reviewed-by: Thomas Gleixner <t...@linutronix.de> Cc: Andrew Morton <a...@linux-foundation.org> Cc: Arjan van de Ven <ar...@linux.intel.com> Cc: Borislav Petkov <b...@alien8.de> Cc: Dave Hansen <dave.han...@intel.com> Cc: Linus Torvalds <torva...@linux-foundation.org> Cc: Mel Gorman <mgor...@suse.de> Cc: Peter Zijlstra <pet...@infradead.org> Cc: Rik van Riel <r...@redhat.com> Cc: linux...@kvack.org Link: http://lkml.kernel.org/r/8bbb2e65bcd249a5f18bfb8128b4689f08ac2b60.1498751203.git.l...@kernel.org Signed-off-by: Ingo Molnar <mi...@kernel.org> Cc: Hugh Dickins <hu...@google.com> Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org> --- Documentation/kernel-parameters.txt | 2 ++ arch/x86/kernel/cpu/common.c | 18 ++++++++++++++++++ 2 files changed, 20 insertions(+) --- a/Documentation/kernel-parameters.txt +++ b/Documentation/kernel-parameters.txt @@ -2555,6 +2555,8 @@ bytes respectively. Such letter suffixes 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 --- a/arch/x86/kernel/cpu/common.c +++ b/arch/x86/kernel/cpu/common.c @@ -162,6 +162,24 @@ static int __init x86_mpx_setup(char *s) } __setup("nompx", x86_mpx_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 */
