[tip:x86/pti] x86/pti: Fix boot problems from Global-bit setting

From: tip-bot for Dave Hansen
Date: Tue Apr 24 2018 - 04:13:27 EST

Commit-ID: 16dce603adc9de4237b7bf2ff5c5290f34373e7b
Gitweb: https://git.kernel.org/tip/16dce603adc9de4237b7bf2ff5c5290f34373e7b
Author: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>
AuthorDate: Fri, 20 Apr 2018 15:20:19 -0700
Committer: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
CommitDate: Tue, 24 Apr 2018 09:50:53 +0200

x86/pti: Fix boot problems from Global-bit setting

Part of the global bit _setting_ patches also includes clearing the
Global bit when it should not be enabled. That is done with
set_memory_nonglobal(), which uses change_page_attr_clear() in
pageattr.c under the covers.

The TLB flushing code inside pageattr.c has has checks like
BUG_ON(irqs_disabled()), looking for interrupt disabling that might
cause deadlocks. But, these also trip in early boot on certain
preempt configurations. Just copy the existing BUG_ON() sequence from
cpa_flush_range() to the other two sites and check for early boot.

Fixes: 39114b7a7 (x86/pti: Never implicitly clear _PAGE_GLOBAL for kernel image)
Reported-by: Mariusz Ceier <mceier@xxxxxxxxx>
Reported-by: Aaro Koskinen <aaro.koskinen@xxxxxxxxx>
Signed-off-by: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>
Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Tested-by: Aaro Koskinen <aaro.koskinen@xxxxxxxxx>
Acked-by: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: Andrea Arcangeli <aarcange@xxxxxxxxxx>
Cc: Juergen Gross <jgross@xxxxxxxx>
Cc: Nadav Amit <namit@xxxxxxxxxx>
Cc: Kees Cook <keescook@xxxxxxxxxx>
Cc: Josh Poimboeuf <jpoimboe@xxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: David Woodhouse <dwmw2@xxxxxxxxxxxxx>
Cc: Hugh Dickins <hughd@xxxxxxxxxx>
Cc: linux-mm@xxxxxxxxx
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Andy Lutomirski <luto@xxxxxxxxxx>
Cc: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Cc: Borislav Petkov <bp@xxxxxxxxx>
Cc: Dan Williams <dan.j.williams@xxxxxxxxx>
Cc: Arjan van de Ven <arjan@xxxxxxxxxxxxxxx>
Link: https://lkml.kernel.org/r/20180420222019.20C4A410@xxxxxxxxxxxxxxxxxx

arch/x86/mm/pageattr.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/x86/mm/pageattr.c b/arch/x86/mm/pageattr.c
index 0f3d50f4c48c..4fadfd2b7017 100644
--- a/arch/x86/mm/pageattr.c
+++ b/arch/x86/mm/pageattr.c
@@ -172,7 +172,7 @@ static void __cpa_flush_all(void *arg)

static void cpa_flush_all(unsigned long cache)
- BUG_ON(irqs_disabled());
+ BUG_ON(irqs_disabled() && !early_boot_irqs_disabled);

on_each_cpu(__cpa_flush_all, (void *) cache, 1);
@@ -236,7 +236,7 @@ static void cpa_flush_array(unsigned long *start, int numpages, int cache,
unsigned long do_wbinvd = cache && numpages >= 1024; /* 4M threshold */

- BUG_ON(irqs_disabled());
+ BUG_ON(irqs_disabled() && !early_boot_irqs_disabled);

on_each_cpu(__cpa_flush_all, (void *) do_wbinvd, 1);