This is a note to let you know that I've just added the patch titled

x86/mm: Add the 'nopcid' boot option to turn off PCID

to the 4.4-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git%3Ba=su...

The filename of the patch is: x86-mm-add-the-nopcid-boot-option-to-turn-off-pcid.patch and it can be found in the queue-4.4 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let stable@vger.kernel.org know about it.

From 0790c9aad84901ca1bdc14746175549c8b5da215 Mon Sep 17 00:00:00 2001

From: Andy Lutomirski luto@kernel.org Date: Thu, 29 Jun 2017 08:53:20 -0700 Subject: x86/mm: Add the 'nopcid' boot option to turn off PCID

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

--- 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 */

Patches currently in stable-queue which might be from luto@kernel.org are

queue-4.4/x86-vm86-32-switch-to-flush_tlb_mm_range-in-mark_screen_rdonly.patch queue-4.4/x86-mm-add-the-nopcid-boot-option-to-turn-off-pcid.patch queue-4.4/x86-mm-enable-cr4.pcide-on-supported-systems.patch queue-4.4/x86-mm-remove-the-up-asm-tlbflush.h-code-always-use-the-formerly-smp-code.patch queue-4.4/x86-mm-reimplement-flush_tlb_page-using-flush_tlb_mm_range.patch queue-4.4/x86-mm-make-flush_tlb_mm_range-more-predictable.patch queue-4.4/x86-mm-remove-flush_tlb-and-flush_tlb_current_task.patch queue-4.4/x86-mm-disable-pcid-on-32-bit-kernels.patch queue-4.4/x86-mm-64-fix-reboot-interaction-with-cr4.pcide.patch