Patch "x86/pti: Add the pti= cmdline option and documentation" has been added to the 4.14-stable tree

Patch "x86/pti: Add the pti= cmdline option and documentation" has been added to the 4.14-stable tree

[gregkh]

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

    x86/pti: Add the pti= cmdline option and documentation

to the 4.14-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     x86-pti-add-the-pti-cmdline-option-and-documentation.patch
and it can be found in the queue-4.14 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 41f4c20b57a4890ea7f56ff8717cc83fefb8d537 Mon Sep 17 00:00:00 2001
From: Borislav Petkov <bp@suse.de>
Date: Tue, 12 Dec 2017 14:39:52 +0100
Subject: x86/pti: Add the pti= cmdline option and documentation

From: Borislav Petkov <bp@suse.de>

commit 41f4c20b57a4890ea7f56ff8717cc83fefb8d537 upstream.

Keep the "nopti" optional for traditional reasons.

[ tglx: Don't allow force on when running on XEN PV and made 'on'
	printout conditional ]

Requested-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Borislav Petkov <bp@suse.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Andy Lutomirsky <luto@kernel.org>
Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: David Laight <David.Laight@aculab.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Eduardo Valentin <eduval@amazon.com>
Cc: Greg KH <gregkh@linuxfoundation.org>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Juergen Gross <jgross@suse.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Will Deacon <will.deacon@arm.com>
Cc: aliguori@amazon.com
Cc: daniel.gruss@iaik.tugraz.at
Cc: hughd@google.com
Cc: keescook@google.com
Link: https://lkml.kernel.org/r/20171212133952.10177-1-bp@alien8.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 Documentation/admin-guide/kernel-parameters.txt |    6 +++++
 arch/x86/mm/pti.c                               |   26 +++++++++++++++++++++++-
 2 files changed, 31 insertions(+), 1 deletion(-)

--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -3255,6 +3255,12 @@
 	pt.		[PARIDE]
 			See Documentation/blockdev/paride.txt.
 
+	pti=		[X86_64]
+			Control user/kernel address space isolation:
+			on - enable
+			off - disable
+			auto - default setting
+
 	pty.legacy_count=
 			[KNL] Number of legacy pty's. Overwrites compiled-in
 			default number.
--- a/arch/x86/mm/pti.c
+++ b/arch/x86/mm/pti.c
@@ -54,21 +54,45 @@ static void __init pti_print_if_insecure
 		pr_info("%s\n", reason);
 }
 
+static void __init pti_print_if_secure(const char *reason)
+{
+	if (!boot_cpu_has_bug(X86_BUG_CPU_INSECURE))
+		pr_info("%s\n", reason);
+}
+
 void __init pti_check_boottime_disable(void)
 {
+	char arg[5];
+	int ret;
+
 	if (hypervisor_is_type(X86_HYPER_XEN_PV)) {
 		pti_print_if_insecure("disabled on XEN PV.");
 		return;
 	}
 
+	ret = cmdline_find_option(boot_command_line, "pti", arg, sizeof(arg));
+	if (ret > 0)  {
+		if (ret == 3 && !strncmp(arg, "off", 3)) {
+			pti_print_if_insecure("disabled on command line.");
+			return;
+		}
+		if (ret == 2 && !strncmp(arg, "on", 2)) {
+			pti_print_if_secure("force enabled on command line.");
+			goto enable;
+		}
+		if (ret == 4 && !strncmp(arg, "auto", 4))
+			goto autosel;
+	}
+
 	if (cmdline_find_option_bool(boot_command_line, "nopti")) {
 		pti_print_if_insecure("disabled on command line.");
 		return;
 	}
 
+autosel:
 	if (!boot_cpu_has_bug(X86_BUG_CPU_INSECURE))
 		return;
-
+enable:
 	setup_force_cpu_cap(X86_FEATURE_PTI);
 }
 


Patches currently in stable-queue which might be from bp@suse.de are

queue-4.14/x86-mm-pti-allow-nx-poison-to-be-set-in-p4d-pgd.patch
queue-4.14/x86-mm-pti-force-entry-through-trampoline-when-pti-active.patch
queue-4.14/x86-mm-pti-disable-global-pages-if-page_table_isolation-y.patch
queue-4.14/x86-mm-pti-add-infrastructure-for-page-table-isolation.patch
queue-4.14/x86-mm-pti-prepare-the-x86-entry-assembly-code-for-entry-exit-cr3-switching.patch
queue-4.14/x86-pti-add-the-pti-cmdline-option-and-documentation.patch
queue-4.14/x86-mm-pti-allocate-a-separate-user-pgd.patch
queue-4.14/x86-mm-pti-populate-user-pgd.patch
queue-4.14/x86-mm-dump_pagetables-add-page-table-directory-to-the-debugfs-vfs-hierarchy.patch