Patch "x86/pti: Make sure the user/kernel PTEs match" has been added to the 4.14-stable tree

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

x86/pti: Make sure the user/kernel PTEs match

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-make-sure-the-user-kernel-ptes-match.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 <[email protected]> know about it.

From: Thomas Gleixner <[email protected]>
Date: Wed, 3 Jan 2018 15:57:59 +0100
Subject: x86/pti: Make sure the user/kernel PTEs match

From: Thomas Gleixner <[email protected]>

commit 52994c256df36fda9a715697431cba9daecb6b11 upstream.

Meelis reported that his K8 Athlon64 emits MCE warnings when PTI is enabled:

[Hardware Error]: Error Addr: 0x0000ffff81e000e0
[Hardware Error]: MC1 Error: L1 TLB multimatch.
[Hardware Error]: cache level: L1, tx: INSN

The address is in the entry area, which is mapped into kernel _AND_ user space. That's special because we switch CR3 while we are executing there.

User mapping:
0xffffffff81e00000-0xffffffff82000000 2M ro PSE GLB x pmd

Kernel mapping:
0xffffffff81000000-0xffffffff82000000 16M ro PSE x pmd

So the K8 is complaining that the TLB entries differ. They differ in the GLB bit.

Drop the GLB bit when installing the user shared mapping.

---
 arch/x86/mm/pti.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

@@ -367,7 +367,8 @@ static void __init pti_setup_espfix64(vo
 static void __init pti_clone_entry_text(void)
 {
 	pti_clone_pmds((unsigned long) __entry_text_start,
-			(unsigned long) __irqentry_text_end, _PAGE_RW);
+			(unsigned long) __irqentry_text_end,
+		       _PAGE_RW | _PAGE_GLOBAL);
 }
 
 /*

Patches currently in stable-queue which might be from [email protected] are

queue-4.14/x86-pti-switch-to-kernel-cr3-at-early-in-entry_syscall_compat.patch queue-4.14/x86-dumpstack-print-registers-for-first-stack-frame.patch queue-4.14/x86-process-define-cpu_tss_rw-in-same-section-as-declaration.patch queue-4.14/x86-pti-make-sure-the-user-kernel-ptes-match.patch queue-4.14/x86-cpu-x86-pti-do-not-enable-pti-on-amd-processors.patch queue-4.14/x86-dumpstack-fix-partial-register-dumps.patch