linux-kernel - [tip:x86/pti] x86/pgtable/pae: Unshare kernel PMDs when PTI is enabled

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Date:   Thu, 19 Jul 2018 16:26:46 -0700
From:   tip-bot for Joerg Roedel <tipbot@...or.com>
To:     linux-tip-commits@...r.kernel.org
Cc:     jgross@...e.com, jpoimboe@...hat.com, gregkh@...uxfoundation.org,
        will.deacon@....com, dhgutteridge@...patico.ca, pavel@....cz,
        torvalds@...ux-foundation.org, aarcange@...hat.com,
        llong@...hat.com, linux-kernel@...r.kernel.org,
        David.Laight@...lab.com, jkosina@...e.cz, luto@...nel.org,
        bp@...en8.de, brgerst@...il.com, mingo@...nel.org,
        tglx@...utronix.de, hpa@...or.com, boris.ostrovsky@...cle.com,
        dvlasenk@...hat.com, dave.hansen@...el.com, eduval@...zon.com,
        peterz@...radead.org, jroedel@...e.de
Subject: [tip:x86/pti] x86/pgtable/pae: Unshare kernel PMDs when PTI is
 enabled

Commit-ID:  7ffcf1497c8ab59a705bfafb7401876fd2f6f71e
Gitweb:     https://git.kernel.org/tip/7ffcf1497c8ab59a705bfafb7401876fd2f6f71e
Author:     Joerg Roedel <jroedel@...e.de>
AuthorDate: Wed, 18 Jul 2018 11:40:53 +0200
Committer:  Thomas Gleixner <tglx@...utronix.de>
CommitDate: Fri, 20 Jul 2018 01:11:40 +0200

x86/pgtable/pae: Unshare kernel PMDs when PTI is enabled

With PTI the per-process LDT must be mapped into the kernel address-space
for each process, which requires separate kernel PMDs per PGD.

Signed-off-by: Joerg Roedel <jroedel@...e.de>
Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
Tested-by: Pavel Machek <pavel@....cz>
Cc: "H . Peter Anvin" <hpa@...or.com>
Cc: linux-mm@...ck.org
Cc: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: Andy Lutomirski <luto@...nel.org>
Cc: Dave Hansen <dave.hansen@...el.com>
Cc: Josh Poimboeuf <jpoimboe@...hat.com>
Cc: Juergen Gross <jgross@...e.com>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Borislav Petkov <bp@...en8.de>
Cc: Jiri Kosina <jkosina@...e.cz>
Cc: Boris Ostrovsky <boris.ostrovsky@...cle.com>
Cc: Brian Gerst <brgerst@...il.com>
Cc: David Laight <David.Laight@...lab.com>
Cc: Denys Vlasenko <dvlasenk@...hat.com>
Cc: Eduardo Valentin <eduval@...zon.com>
Cc: Greg KH <gregkh@...uxfoundation.org>
Cc: Will Deacon <will.deacon@....com>
Cc: aliguori@...zon.com
Cc: daniel.gruss@...k.tugraz.at
Cc: hughd@...gle.com
Cc: keescook@...gle.com
Cc: Andrea Arcangeli <aarcange@...hat.com>
Cc: Waiman Long <llong@...hat.com>
Cc: "David H . Gutteridge" <dhgutteridge@...patico.ca>
Cc: joro@...tes.org
Link: https://lkml.kernel.org/r/1531906876-13451-17-git-send-email-joro@8bytes.org

---
 arch/x86/include/asm/pgtable-3level_types.h | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/arch/x86/include/asm/pgtable-3level_types.h b/arch/x86/include/asm/pgtable-3level_types.h
index 6a59a6d0cc50..78038e057876 100644
--- a/arch/x86/include/asm/pgtable-3level_types.h
+++ b/arch/x86/include/asm/pgtable-3level_types.h
@@ -21,9 +21,10 @@ typedef union {
 #endif	/* !__ASSEMBLY__ */

 #ifdef CONFIG_PARAVIRT
-#define SHARED_KERNEL_PMD	(pv_info.shared_kernel_pmd)
+#define SHARED_KERNEL_PMD	((!static_cpu_has(X86_FEATURE_PTI) &&	\
+				 (pv_info.shared_kernel_pmd)))
 #else
-#define SHARED_KERNEL_PMD	1
+#define SHARED_KERNEL_PMD	(!static_cpu_has(X86_FEATURE_PTI))
 #endif

 /*