Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > linux.kernel > #1677891

[PATCH v4 08/10] x86/mm: Add nopcid to turn off PCID

Show all headers | View raw

The parameter is only present on x86_64 systems to save a few bytes,
as PCID is always disabled on x86_32.

Reviewed-by: Nadav Amit <nadav.amit@gmail.com>
Reviewed-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andy Lutomirski <luto@kernel.org>
---
 Documentation/admin-guide/kernel-parameters.txt |  2 ++
 arch/x86/kernel/cpu/common.c                    | 18 ++++++++++++++++++
 2 files changed, 20 insertions(+)

diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index 7737ab5d04b2..705666a44ba2 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -2648,6 +2648,8 @@
 	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 c8b39870f33e..904485e7b230 100644
--- a/arch/x86/kernel/cpu/common.c
+++ b/arch/x86/kernel/cpu/common.c
@@ -168,6 +168,24 @@ 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 */
-- 
2.9.4

Back to linux.kernel | Previous | Next — Previous in thread | Next in thread | Find similar | Unroll thread

Thread

[PATCH v4 00/10] PCID and improved laziness Andy Lutomirski <luto@kernel.org> - 2017-06-29 18:00 +0200
  [PATCH v4 02/10] x86/mm: Delete a big outdated comment about TLB flushing Andy Lutomirski <luto@kernel.org> - 2017-06-29 18:00 +0200
    [tip:x86/mm] x86/mm: Delete a big outdated comment about TLB  flushing tip-bot for Andy Lutomirski <tipbot@zytor.com> - 2017-06-30 15:20 +0200
  [PATCH v4 09/10] x86/mm: Enable CR4.PCIDE on supported systems Andy Lutomirski <luto@kernel.org> - 2017-06-29 18:00 +0200
  [PATCH v4 08/10] x86/mm: Add nopcid to turn off PCID Andy Lutomirski <luto@kernel.org> - 2017-06-29 18:00 +0200
  [PATCH v4 05/10] x86/mm: Rework lazy TLB mode and TLB freshness tracking Andy Lutomirski <luto@kernel.org> - 2017-06-29 18:00 +0200
  [PATCH v4 03/10] x86/mm: Give each mm TLB flush generation a unique ID Andy Lutomirski <luto@kernel.org> - 2017-06-29 18:00 +0200
  [PATCH v4 06/10] x86/mm: Stop calling leave_mm() in idle code Andy Lutomirski <luto@kernel.org> - 2017-06-29 18:00 +0200
  [PATCH v4 01/10] x86/mm: Don't reenter flush_tlb_func_common() Andy Lutomirski <luto@kernel.org> - 2017-06-29 18:00 +0200
    [tip:x86/mm] x86/mm: Don't reenter flush_tlb_func_common() tip-bot for Andy Lutomirski <tipbot@zytor.com> - 2017-06-30 15:20 +0200
  [PATCH v4 04/10] x86/mm: Track the TLB's tlb_gen and update the flushing algorithm Andy Lutomirski <luto@kernel.org> - 2017-06-29 18:00 +0200
  Re: [PATCH v4 00/10] PCID and improved laziness Matt Fleming <matt@codeblueprint.co.uk> - 2017-06-30 14:50 +0200

csiph-web