pve-edge-kernel/patches/kernel/0015-x86-mm-Add-the-nopcid-boot-option-to-turn-off-PCID.patch

From 95e4ae0f4ad738ff6ec8e44ab9fa5529d4369655 Mon Sep 17 00:00:00 2001
From: Andy Lutomirski <[email protected]>
Date: Thu, 29 Jun 2017 08:53:20 -0700
Subject: [PATCH 015/232] x86/mm: Add the 'nopcid' boot option to turn off PCID
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

CVE-2017-5754

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 <[email protected]>
Reviewed-by: Nadav Amit <[email protected]>
Reviewed-by: Borislav Petkov <[email protected]>
Reviewed-by: Thomas Gleixner <[email protected]>
Cc: Andrew Morton <[email protected]>
Cc: Arjan van de Ven <[email protected]>
Cc: Borislav Petkov <[email protected]>
Cc: Dave Hansen <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: Mel Gorman <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Rik van Riel <[email protected]>
Cc: [email protected]
Link: http://lkml.kernel.org/r/8bbb2e65bcd249a5f18bfb8128b4689f08ac2b60.1498751203.git.luto@kernel.org
Signed-off-by: Ingo Molnar <[email protected]>
(cherry picked from commit 0790c9aad84901ca1bdc14746175549c8b5da215)
Signed-off-by: Andy Whitcroft <[email protected]>
Signed-off-by: Kleber Sacilotto de Souza <[email protected]>
(cherry picked from commit 62d3a63645c17611fe8ccc0c5adc5e840d9cff7b)
Signed-off-by: Fabian Grünbichler <[email protected]>
---
 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 73fd6abac39b..3510e255ef4c 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -2700,6 +2700,8 @@
 	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 */
-- 
2.14.2