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[209.132.180.67]) by mx.google.com with ESMTP id c12-v6si620921pll.498.2018.04.09.10.17.07; Mon, 09 Apr 2018 10:17:44 -0700 (PDT) Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67; Authentication-Results: mx.google.com; spf=pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753846AbeDIRNV (ORCPT + 99 others); Mon, 9 Apr 2018 13:13:21 -0400 Received: from terminus.zytor.com ([198.137.202.136]:41291 "EHLO terminus.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753814AbeDIRNT (ORCPT ); Mon, 9 Apr 2018 13:13:19 -0400 Received: from terminus.zytor.com (localhost [127.0.0.1]) by terminus.zytor.com (8.15.2/8.15.2) with ESMTP id w39HCMtG1894202; Mon, 9 Apr 2018 10:12:22 -0700 Received: (from tipbot@localhost) by terminus.zytor.com (8.15.2/8.15.2/Submit) id w39HCLeN1894199; Mon, 9 Apr 2018 10:12:21 -0700 Date: Mon, 9 Apr 2018 10:12:21 -0700 X-Authentication-Warning: terminus.zytor.com: tipbot set sender to tipbot@zytor.com using -f From: tip-bot for Dave Hansen Message-ID: Cc: jgross@suse.com, peterz@infradead.org, gregkh@linuxfoundation.org, namit@vmware.com, hughd@google.com, torvalds@linux-foundation.org, tglx@linutronix.de, keescook@google.com, dan.j.williams@intel.com, arjan@linux.intel.com, jpoimboe@redhat.com, bp@alien8.de, mingo@kernel.org, aarcange@redhat.com, dave.hansen@linux.intel.com, linux-kernel@vger.kernel.org, dwmw2@infradead.org, luto@kernel.org, hpa@zytor.com Reply-To: hughd@google.com, torvalds@linux-foundation.org, tglx@linutronix.de, gregkh@linuxfoundation.org, peterz@infradead.org, jgross@suse.com, namit@vmware.com, luto@kernel.org, dwmw2@infradead.org, hpa@zytor.com, arjan@linux.intel.com, keescook@google.com, dan.j.williams@intel.com, jpoimboe@redhat.com, bp@alien8.de, mingo@kernel.org, aarcange@redhat.com, dave.hansen@linux.intel.com, linux-kernel@vger.kernel.org In-Reply-To: <20180406205504.9B0F44A9@viggo.jf.intel.com> References: <20180406205504.9B0F44A9@viggo.jf.intel.com> To: linux-tip-commits@vger.kernel.org Subject: [tip:x86/pti] x86/mm: Undo double _PAGE_PSE clearing Git-Commit-ID: 606c7193d5fbf8ea3dafc8a9468f719fbf1d7160 X-Mailer: tip-git-log-daemon Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain; charset=UTF-8 Content-Disposition: inline X-Spam-Status: No, score=-2.9 required=5.0 tests=ALL_TRUSTED,BAYES_00 autolearn=ham autolearn_force=no version=3.4.1 X-Spam-Checker-Version: SpamAssassin 3.4.1 (2015-04-28) on terminus.zytor.com Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Commit-ID: 606c7193d5fbf8ea3dafc8a9468f719fbf1d7160 Gitweb: https://git.kernel.org/tip/606c7193d5fbf8ea3dafc8a9468f719fbf1d7160 Author: Dave Hansen AuthorDate: Fri, 6 Apr 2018 13:55:04 -0700 Committer: Ingo Molnar CommitDate: Mon, 9 Apr 2018 18:27:32 +0200 x86/mm: Undo double _PAGE_PSE clearing When clearing _PAGE_PRESENT on a huge page, we need to be careful to also clear _PAGE_PSE, otherwise it might still get confused for a valid large page table entry. We do that near the spot where we *set* _PAGE_PSE. That's fine, but it's unnecessary. pgprot_large_2_4k() already did it. BTW, I also noticed that pgprot_large_2_4k() and pgprot_4k_2_large() are not symmetric. pgprot_large_2_4k() clears _PAGE_PSE (because it is aliased to _PAGE_PAT) but pgprot_4k_2_large() does not put _PAGE_PSE back. Bummer. Also, add some comments and change "promote" to "move". "Promote" seems an odd word to move when we are logically moving a bit to a lower bit position. Also add an extra line return to make it clear to which line the comment applies. Signed-off-by: Dave Hansen Cc: Andrea Arcangeli Cc: Andy Lutomirski Cc: Arjan van de Ven Cc: Borislav Petkov Cc: Dan Williams Cc: David Woodhouse Cc: Greg Kroah-Hartman Cc: Hugh Dickins Cc: Josh Poimboeuf Cc: Juergen Gross Cc: Kees Cook Cc: Linus Torvalds Cc: Nadav Amit Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: linux-mm@kvack.org Link: http://lkml.kernel.org/r/20180406205504.9B0F44A9@viggo.jf.intel.com Signed-off-by: Ingo Molnar --- arch/x86/mm/pageattr.c | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-) diff --git a/arch/x86/mm/pageattr.c b/arch/x86/mm/pageattr.c index 4d369d5c04c5..d3442dfdfced 100644 --- a/arch/x86/mm/pageattr.c +++ b/arch/x86/mm/pageattr.c @@ -583,6 +583,7 @@ try_preserve_large_page(pte_t *kpte, unsigned long address, * up accordingly. */ old_pte = *kpte; + /* Clear PSE (aka _PAGE_PAT) and move PAT bit to correct position */ req_prot = pgprot_large_2_4k(old_prot); pgprot_val(req_prot) &= ~pgprot_val(cpa->mask_clr); @@ -597,8 +598,6 @@ try_preserve_large_page(pte_t *kpte, unsigned long address, req_prot = pgprot_clear_protnone_bits(req_prot); if (pgprot_val(req_prot) & _PAGE_PRESENT) pgprot_val(req_prot) |= _PAGE_PSE; - else - pgprot_val(req_prot) &= ~_PAGE_PSE; req_prot = canon_pgprot(req_prot); /* @@ -684,8 +683,12 @@ __split_large_page(struct cpa_data *cpa, pte_t *kpte, unsigned long address, switch (level) { case PG_LEVEL_2M: ref_prot = pmd_pgprot(*(pmd_t *)kpte); - /* clear PSE and promote PAT bit to correct position */ + /* + * Clear PSE (aka _PAGE_PAT) and move + * PAT bit to correct position. + */ ref_prot = pgprot_large_2_4k(ref_prot); + ref_pfn = pmd_pfn(*(pmd_t *)kpte); break;