From nobody Tue Feb 10 09:02:02 2026 Delivered-To: importer@patchew.org Authentication-Results: mx.zohomail.com; spf=pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) smtp.mailfrom=qemu-devel-bounces+importer=patchew.org@nongnu.org; dmarc=fail(p=none dis=none) header.from=arm.com ARC-Seal: i=1; a=rsa-sha256; t=1614608786; cv=none; d=zohomail.com; s=zohoarc; b=K1BSOXT974mJOjkOv7N6x2iVl+YoWsqLJznNAim7i2YsCtXsU6+vFS9pbbOCSMW1coToUJuNtOEhnJup3Ln0NCINGZ8AOSmqeeSTumrfd34SCcmBbqE5sXBianYhZaQnjlIpxiAZK2zZ3BqewdkNSp+mqPIbzwthl9PKb5jqZ4Y= ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=zohomail.com; s=zohoarc; t=1614608786; h=Content-Transfer-Encoding:Cc:Date:From:In-Reply-To:List-Subscribe:List-Post:List-Id:List-Archive:List-Help:List-Unsubscribe:MIME-Version:Message-ID:References:Sender:Subject:To; bh=surRDNkTU7TNEb1A7uf1S+9HhVBxYhBENzKON8xpnOs=; b=PjXnOI8c6sVFwF8gJzEHNLf0cexcYUtFoToR+ia5+zN0sgYptnbjIIbXLiyykYFlGPSjRu/8W3pcpCSFQe+etCgGxPkp6XomtG51wwYS+/j+a090eY/IvcEntmau7UiAVLb/iT0xNmkbZJpIGoN2R2txpkmyySFgaz/dGY9E20c= ARC-Authentication-Results: i=1; mx.zohomail.com; spf=pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) smtp.mailfrom=qemu-devel-bounces+importer=patchew.org@nongnu.org; dmarc=fail header.from= (p=none dis=none) header.from= Return-Path: Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) by mx.zohomail.com with SMTPS id 1614608786339316.84643342399704; Mon, 1 Mar 2021 06:26:26 -0800 (PST) Received: from localhost ([::1]:52738 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1lGjVB-00057l-Ag for importer@patchew.org; Mon, 01 Mar 2021 09:26:25 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]:41860) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1lGjSV-0002LI-PF for qemu-devel@nongnu.org; Mon, 01 Mar 2021 09:23:39 -0500 Received: from foss.arm.com ([217.140.110.172]:51612) by eggs.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1lGjST-0004o8-HS for qemu-devel@nongnu.org; Mon, 01 Mar 2021 09:23:39 -0500 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 49F571063; Mon, 1 Mar 2021 06:23:36 -0800 (PST) Received: from e112269-lin.arm.com (unknown [172.31.20.19]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 7D7D63F70D; Mon, 1 Mar 2021 06:23:33 -0800 (PST) From: Steven Price To: Catalin Marinas , Marc Zyngier , Will Deacon Subject: [PATCH v9 1/6] arm64: mte: Sync tags for pages where PTE is untagged Date: Mon, 1 Mar 2021 14:23:10 +0000 Message-Id: <20210301142315.30920-2-steven.price@arm.com> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20210301142315.30920-1-steven.price@arm.com> References: <20210301142315.30920-1-steven.price@arm.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Received-SPF: pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) client-ip=209.51.188.17; envelope-from=qemu-devel-bounces+importer=patchew.org@nongnu.org; helo=lists.gnu.org; Received-SPF: pass client-ip=217.140.110.172; envelope-from=steven.price@arm.com; helo=foss.arm.com X-Spam_score_int: -41 X-Spam_score: -4.2 X-Spam_bar: ---- X-Spam_report: (-4.2 / 5.0 requ) BAYES_00=-1.9, RCVD_IN_DNSWL_MED=-2.3, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Mark Rutland , Peter Maydell , "Dr. David Alan Gilbert" , Andrew Jones , Haibo Xu , Suzuki K Poulose , qemu-devel@nongnu.org, Dave Martin , Juan Quintela , Richard Henderson , linux-kernel@vger.kernel.org, Steven Price , James Morse , Julien Thierry , Thomas Gleixner , kvmarm@lists.cs.columbia.edu, linux-arm-kernel@lists.infradead.org Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org Sender: "Qemu-devel" Content-Type: text/plain; charset="utf-8" A KVM guest could store tags in a page even if the VMM hasn't mapped the page with PROT_MTE. So when restoring pages from swap we will need to check to see if there are any saved tags even if !pte_tagged(). However don't check pages which are !pte_valid_user() as these will not have been swapped out. Signed-off-by: Steven Price --- arch/arm64/include/asm/pgtable.h | 2 +- arch/arm64/kernel/mte.c | 16 ++++++++++++---- 2 files changed, 13 insertions(+), 5 deletions(-) diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/pgta= ble.h index e17b96d0e4b5..84166625c989 100644 --- a/arch/arm64/include/asm/pgtable.h +++ b/arch/arm64/include/asm/pgtable.h @@ -312,7 +312,7 @@ static inline void set_pte_at(struct mm_struct *mm, uns= igned long addr, __sync_icache_dcache(pte); =20 if (system_supports_mte() && - pte_present(pte) && pte_tagged(pte) && !pte_special(pte)) + pte_present(pte) && pte_valid_user(pte) && !pte_special(pte)) mte_sync_tags(ptep, pte); =20 __check_racy_pte_update(mm, ptep, pte); diff --git a/arch/arm64/kernel/mte.c b/arch/arm64/kernel/mte.c index b3c70a612c7a..e016ab57ea36 100644 --- a/arch/arm64/kernel/mte.c +++ b/arch/arm64/kernel/mte.c @@ -26,17 +26,23 @@ u64 gcr_kernel_excl __ro_after_init; =20 static bool report_fault_once =3D true; =20 -static void mte_sync_page_tags(struct page *page, pte_t *ptep, bool check_= swap) +static void mte_sync_page_tags(struct page *page, pte_t *ptep, bool check_= swap, + bool pte_is_tagged) { pte_t old_pte =3D READ_ONCE(*ptep); =20 if (check_swap && is_swap_pte(old_pte)) { swp_entry_t entry =3D pte_to_swp_entry(old_pte); =20 - if (!non_swap_entry(entry) && mte_restore_tags(entry, page)) + if (!non_swap_entry(entry) && mte_restore_tags(entry, page)) { + set_bit(PG_mte_tagged, &page->flags); return; + } } =20 + if (!pte_is_tagged || test_and_set_bit(PG_mte_tagged, &page->flags)) + return; + page_kasan_tag_reset(page); /* * We need smp_wmb() in between setting the flags and clearing the @@ -54,11 +60,13 @@ void mte_sync_tags(pte_t *ptep, pte_t pte) struct page *page =3D pte_page(pte); long i, nr_pages =3D compound_nr(page); bool check_swap =3D nr_pages =3D=3D 1; + bool pte_is_tagged =3D pte_tagged(pte); =20 /* if PG_mte_tagged is set, tags have already been initialised */ for (i =3D 0; i < nr_pages; i++, page++) { - if (!test_and_set_bit(PG_mte_tagged, &page->flags)) - mte_sync_page_tags(page, ptep, check_swap); + if (!test_bit(PG_mte_tagged, &page->flags)) + mte_sync_page_tags(page, ptep, check_swap, + pte_is_tagged); } } =20 --=20 2.20.1