From nobody Tue Nov 11 20:54:54 2025 Delivered-To: importer@patchew.org Received-SPF: pass (zoho.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; Authentication-Results: mx.zohomail.com; spf=pass (zoho.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=redhat.com ARC-Seal: i=1; a=rsa-sha256; t=1565609386; cv=none; d=zoho.com; s=zohoarc; b=AhlLIp05O+GNnzd9/tJSZKneO+NF0PIEmQr9h3Q6c+OvVyfjo2L0m7ah83wnlx6E3XGtU0nwMpHQM1gpa7teAiNIiXpVZoIgLpzfcQM/qIvFqHYl1yGWNo9A5aYnQIXz7S9WLvanBhTP/znxahB+ddlZd8O2gx73c0EtJYMPu5U= ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=zoho.com; s=zohoarc; t=1565609386; 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:ARC-Authentication-Results; bh=qgsZQgY4pXJTfnRE9x4Nn7CZ8u6NKG8QElN3CKdTZuo=; b=kRJgSU1/0qYicdd/RpMtfFgF4X9Z1O4I2WAVS6E7KwzirVsUEXOw1k2EdwkviY4p1u5SWN713KelfGSfwC8ZMP1UmSkiI3nXnEIAbqoIsN1s5cEVuIuE/jVyIraMU+RNCWpTjUFWGwetjdHW3LGEo2q9Rrtu2GA15NIccbh3NaM= ARC-Authentication-Results: i=1; mx.zoho.com; spf=pass (zoho.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 1565609386411415.94503923049285; Mon, 12 Aug 2019 04:29:46 -0700 (PDT) Received: from localhost ([::1]:44450 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.86_2) (envelope-from ) id 1hx8WH-0000AY-Il for importer@patchew.org; Mon, 12 Aug 2019 07:29:45 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:34681) by lists.gnu.org with esmtp (Exim 4.86_2) (envelope-from ) id 1hx8Ub-0004e2-OY for qemu-devel@nongnu.org; Mon, 12 Aug 2019 07:28:03 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1hx8Ua-0002c5-Ma for qemu-devel@nongnu.org; Mon, 12 Aug 2019 07:28:01 -0400 Received: from mx1.redhat.com ([209.132.183.28]:58368) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1hx8Ua-0002bV-Hg; Mon, 12 Aug 2019 07:28:00 -0400 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id CC630182D; Mon, 12 Aug 2019 11:27:59 +0000 (UTC) Received: from t460s.redhat.com (ovpn-117-110.ams2.redhat.com [10.36.117.110]) by smtp.corp.redhat.com (Postfix) with ESMTP id 0361B600C4; Mon, 12 Aug 2019 11:27:57 +0000 (UTC) From: David Hildenbrand To: qemu-devel@nongnu.org Date: Mon, 12 Aug 2019 13:27:36 +0200 Message-Id: <20190812112737.6652-6-david@redhat.com> In-Reply-To: <20190812112737.6652-1-david@redhat.com> References: <20190812112737.6652-1-david@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.11 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.30]); Mon, 12 Aug 2019 11:27:59 +0000 (UTC) Content-Transfer-Encoding: quoted-printable X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-Received-From: 209.132.183.28 Subject: [Qemu-devel] [PATCH-for-4.2 v1 5/6] s390x/mmu: Better storage key reference and change bit handling 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: Thomas Huth , Janosch Frank , David Hildenbrand , Cornelia Huck , Halil Pasic , Christian Borntraeger , qemu-s390x@nongnu.org, Richard Henderson Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org Sender: "Qemu-devel" Content-Type: text/plain; charset="utf-8" Any access sets the reference bit. In case we have a read-fault, we should not allow writes to the TLB entry if the change bit was not already set. This is a preparation for proper storage-key reference/change bit handling in TCG and a fix for KVM whereby read accesses would set the change bit (old KVM versions without the ioctl to carry out the translation). Signed-off-by: David Hildenbrand Reviewed-by: Cornelia Huck --- target/s390x/mmu_helper.c | 24 +++++++++++++++++++----- 1 file changed, 19 insertions(+), 5 deletions(-) diff --git a/target/s390x/mmu_helper.c b/target/s390x/mmu_helper.c index 227a822e42..ba4b460ac6 100644 --- a/target/s390x/mmu_helper.c +++ b/target/s390x/mmu_helper.c @@ -421,14 +421,28 @@ nodat: return 0; } =20 - if (*flags & PAGE_READ) { - key |=3D SK_R; - } - - if (*flags & PAGE_WRITE) { + switch (rw) { + case MMU_DATA_LOAD: + case MMU_INST_FETCH: + /* + * The TLB entry has to remain write-protected on read-faults = if + * the storage key does not indicate a change already. Otherwi= se + * we might miss setting the change bit on write accesses. + */ + if (!(key & SK_C)) { + *flags &=3D ~PAGE_WRITE; + } + break; + case MMU_DATA_STORE: key |=3D SK_C; + break; + default: + g_assert_not_reached(); } =20 + /* Any store/fetch sets the reference bit */ + key |=3D SK_R; + r =3D skeyclass->set_skeys(ss, *raddr / TARGET_PAGE_SIZE, 1, &key); if (r) { trace_set_skeys_nonzero(r); --=20 2.21.0