From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755187AbeDDBNo (ORCPT ); Tue, 3 Apr 2018 21:13:44 -0400 Received: from mga12.intel.com ([192.55.52.136]:41790 "EHLO mga12.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754985AbeDDBMx (ORCPT ); Tue, 3 Apr 2018 21:12:53 -0400 X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.48,403,1517904000"; d="scan'208";a="39177868" Subject: [PATCH 09/11] x86/pti: enable global pages for shared areas To: linux-kernel@vger.kernel.org Cc: linux-mm@kvack.org, Dave Hansen , aarcange@redhat.com, luto@kernel.org, torvalds@linux-foundation.org, keescook@google.com, hughd@google.com, jgross@suse.com, x86@kernel.org, namit@vmware.com From: Dave Hansen Date: Tue, 03 Apr 2018 18:10:07 -0700 References: <20180404010946.6186729B@viggo.jf.intel.com> In-Reply-To: <20180404010946.6186729B@viggo.jf.intel.com> Message-Id: <20180404011007.A381CC8A@viggo.jf.intel.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Dave Hansen The entry/exit text and cpu_entry_area are mapped into userspace and the kernel. But, they are not _PAGE_GLOBAL. This creates unnecessary TLB misses. Add the _PAGE_GLOBAL flag for these areas. Signed-off-by: Dave Hansen Cc: Andrea Arcangeli Cc: Andy Lutomirski Cc: Linus Torvalds Cc: Kees Cook Cc: Hugh Dickins Cc: Juergen Gross Cc: x86@kernel.org Cc: Nadav Amit --- b/arch/x86/mm/cpu_entry_area.c | 10 +++++++++- b/arch/x86/mm/pti.c | 14 +++++++++++++- 2 files changed, 22 insertions(+), 2 deletions(-) diff -puN arch/x86/mm/cpu_entry_area.c~kpti-why-no-global arch/x86/mm/cpu_entry_area.c --- a/arch/x86/mm/cpu_entry_area.c~kpti-why-no-global 2018-04-02 16:41:17.157605167 -0700 +++ b/arch/x86/mm/cpu_entry_area.c 2018-04-02 16:41:17.162605167 -0700 @@ -27,8 +27,16 @@ EXPORT_SYMBOL(get_cpu_entry_area); void cea_set_pte(void *cea_vaddr, phys_addr_t pa, pgprot_t flags) { unsigned long va = (unsigned long) cea_vaddr; + pte_t pte = pfn_pte(pa >> PAGE_SHIFT, flags); - set_pte_vaddr(va, pfn_pte(pa >> PAGE_SHIFT, flags)); + /* + * The cpu_entry_area is shared between the user and kernel + * page tables. All of its ptes can safely be global. + */ + if (boot_cpu_has(X86_FEATURE_PGE)) + pte = pte_set_flags(pte, _PAGE_GLOBAL); + + set_pte_vaddr(va, pte); } static void __init diff -puN arch/x86/mm/pti.c~kpti-why-no-global arch/x86/mm/pti.c --- a/arch/x86/mm/pti.c~kpti-why-no-global 2018-04-02 16:41:17.159605167 -0700 +++ b/arch/x86/mm/pti.c 2018-04-02 16:41:17.163605167 -0700 @@ -300,6 +300,18 @@ pti_clone_pmds(unsigned long start, unsi return; /* + * Setting 'target_pmd' below creates a mapping in both + * the user and kernel page tables. It is effectively + * global, so set it as global in both copies. Note: + * the X86_FEATURE_PGE check is not _required_ because + * the CPU ignores _PAGE_GLOBAL when PGE is not + * supported. The check keeps consistentency with + * code that only set this bit when supported. + */ + if (boot_cpu_has(X86_FEATURE_PGE)) + *pmd = pmd_set_flags(*pmd, _PAGE_GLOBAL); + + /* * Copy the PMD. That is, the kernelmode and usermode * tables will share the last-level page tables of this * address range @@ -348,7 +360,7 @@ static void __init pti_clone_entry_text( { pti_clone_pmds((unsigned long) __entry_text_start, (unsigned long) __irqentry_text_end, - _PAGE_RW | _PAGE_GLOBAL); + _PAGE_RW); } /* _