linux-kernel - [tip:x86/mm] x86/mm: Do not use paravirtualized calls in native_set

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Message-ID: <tip-a5b162b2ecb013ed517ab5ce90079117ada743f4@git.kernel.org>
Date:   Mon, 12 Mar 2018 05:16:03 -0700
From:   "tip-bot for Kirill A. Shutemov" <tipbot@...or.com>
To:     linux-tip-commits@...r.kernel.org
Cc:     hpa@...or.com, bp@...en8.de, dvlasenk@...hat.com,
        tglx@...utronix.de, mingo@...nel.org, peterz@...radead.org,
        jpoimboe@...hat.com, linux-kernel@...r.kernel.org,
        torvalds@...ux-foundation.org, luto@...nel.org, brgerst@...il.com,
        kirill.shutemov@...ux.intel.com, fengguang.wu@...el.com
Subject: [tip:x86/mm] x86/mm: Do not use paravirtualized calls in
 native_set_p4d()

Commit-ID:  a5b162b2ecb013ed517ab5ce90079117ada743f4
Gitweb:     https://git.kernel.org/tip/a5b162b2ecb013ed517ab5ce90079117ada743f4
Author:     Kirill A. Shutemov <kirill.shutemov@...ux.intel.com>
AuthorDate: Mon, 5 Mar 2018 11:16:41 +0300
Committer:  Ingo Molnar <mingo@...nel.org>
CommitDate: Mon, 12 Mar 2018 10:30:48 +0100

x86/mm: Do not use paravirtualized calls in native_set_p4d()

In 4-level paging mode, native_set_p4d() updates the entry in the top-level
page table. With PTI, update to the top-level kernel page table requires
update to the userspace copy of the table as well, using pti_set_user_pgd().

native_set_p4d() uses p4d_val() and pgd_val() to convert types between
p4d_t and pgd_t.

p4d_val() and pgd_val() are paravirtualized and we must not use them in
native helpers, as they crash the boot in paravirtualized environments.

Replace p4d_val() and pgd_val() with native_p4d_val() and
native_pgd_val() in native_set_p4d().

Reported-by: Fengguang Wu <fengguang.wu@...el.com>
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@...ux.intel.com>
Cc: Andy Lutomirski <luto@...nel.org>
Cc: Borislav Petkov <bp@...en8.de>
Cc: Brian Gerst <brgerst@...il.com>
Cc: Denys Vlasenko <dvlasenk@...hat.com>
Cc: H. Peter Anvin <hpa@...or.com>
Cc: Josh Poimboeuf <jpoimboe@...hat.com>
Cc: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Thomas Gleixner <tglx@...utronix.de>
Fixes: 91f606a8fa68 ("x86/mm: Replace compile-time checks for 5-level paging with runtime-time checks")
Link: http://lkml.kernel.org/r/20180305081641.4290-1-kirill.shutemov@linux.intel.com
Signed-off-by: Ingo Molnar <mingo@...nel.org>
---
 arch/x86/include/asm/pgtable_64.h | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/x86/include/asm/pgtable_64.h b/arch/x86/include/asm/pgtable_64.h
index 81dda8d1d0bd..163e01a0631d 100644
--- a/arch/x86/include/asm/pgtable_64.h
+++ b/arch/x86/include/asm/pgtable_64.h
@@ -224,9 +224,9 @@ static inline void native_set_p4d(p4d_t *p4dp, p4d_t p4d)
 		return;
 	}
 
-	pgd = native_make_pgd(p4d_val(p4d));
+	pgd = native_make_pgd(native_p4d_val(p4d));
 	pgd = pti_set_user_pgd((pgd_t *)p4dp, pgd);
-	*p4dp = native_make_p4d(pgd_val(pgd));
+	*p4dp = native_make_p4d(native_pgd_val(pgd));
 }
 
 static inline void native_p4d_clear(p4d_t *p4d)