linux-kernel - [PATCH v4 6/6] x86/paravirt: avoid needless paravirt step clearing page table entries

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <20200815100641.26362-7-jgross@suse.com>
Date:   Sat, 15 Aug 2020 12:06:41 +0200
From:   Juergen Gross <jgross@...e.com>
To:     xen-devel@...ts.xenproject.org, x86@...nel.org,
        virtualization@...ts.linux-foundation.org,
        linux-kernel@...r.kernel.org
Cc:     Juergen Gross <jgross@...e.com>, Deep Shah <sdeep@...are.com>,
        "VMware, Inc." <pv-drivers@...are.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        "H. Peter Anvin" <hpa@...or.com>
Subject: [PATCH v4 6/6] x86/paravirt: avoid needless paravirt step clearing page table entries

pte_clear() et al are based on tw0 paravirt steps today: one step to
create a page table entry with all zeroes, and one step to write this
entry value.

Drop the first step as it is completely useless.

Signed-off-by: Juergen Gross <jgross@...e.com>
---
 arch/x86/include/asm/paravirt.h | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/arch/x86/include/asm/paravirt.h b/arch/x86/include/asm/paravirt.h
index f0464b88ea1e..d25cc6830e89 100644
--- a/arch/x86/include/asm/paravirt.h
+++ b/arch/x86/include/asm/paravirt.h
@@ -448,7 +448,7 @@ static inline pudval_t pud_val(pud_t pud)
 
 static inline void pud_clear(pud_t *pudp)
 {
-	set_pud(pudp, __pud(0));
+	set_pud(pudp, native_make_pud(0));
 }
 
 static inline void set_p4d(p4d_t *p4dp, p4d_t p4d)
@@ -485,15 +485,15 @@ static inline void __set_pgd(pgd_t *pgdp, pgd_t pgd)
 } while (0)
 
 #define pgd_clear(pgdp) do {						\
-	if (pgtable_l5_enabled())						\
-		set_pgd(pgdp, __pgd(0));				\
+	if (pgtable_l5_enabled())					\
+		set_pgd(pgdp, native_make_pgd(0));			\
 } while (0)
 
 #endif  /* CONFIG_PGTABLE_LEVELS == 5 */
 
 static inline void p4d_clear(p4d_t *p4dp)
 {
-	set_p4d(p4dp, __p4d(0));
+	set_p4d(p4dp, native_make_p4d(0));
 }
 
 static inline void set_pte_atomic(pte_t *ptep, pte_t pte)
@@ -504,12 +504,12 @@ static inline void set_pte_atomic(pte_t *ptep, pte_t pte)
 static inline void pte_clear(struct mm_struct *mm, unsigned long addr,
 			     pte_t *ptep)
 {
-	set_pte(ptep, __pte(0));
+	set_pte(ptep, native_make_pte(0));
 }
 
 static inline void pmd_clear(pmd_t *pmdp)
 {
-	set_pmd(pmdp, __pmd(0));
+	set_pmd(pmdp, native_make_pmd(0));
 }
 
 #define  __HAVE_ARCH_START_CONTEXT_SWITCH
-- 
2.26.2