From patchwork Wed Aug 21 09:22:50 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: David Hildenbrand X-Patchwork-Id: 11106195 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 88F75112C for ; Wed, 21 Aug 2019 09:24:32 +0000 (UTC) Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 6A914233FC for ; Wed, 21 Aug 2019 09:24:32 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 6A914233FC Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+patchwork-qemu-devel=patchwork.kernel.org@nongnu.org Received: from localhost ([::1]:46392 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1i0Mr1-00009F-Hg for patchwork-qemu-devel@patchwork.kernel.org; Wed, 21 Aug 2019 05:24:31 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:36865) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1i0Mpb-0006DT-U3 for qemu-devel@nongnu.org; Wed, 21 Aug 2019 05:23:04 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1i0Mpa-0001BU-Jz for qemu-devel@nongnu.org; Wed, 21 Aug 2019 05:23:03 -0400 Received: from mx1.redhat.com ([209.132.183.28]:39420) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1i0Mpa-0001B0-Bn; Wed, 21 Aug 2019 05:23:02 -0400 Received: from smtp.corp.redhat.com (int-mx06.intmail.prod.int.phx2.redhat.com [10.5.11.16]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id AA571106BB20; Wed, 21 Aug 2019 09:23:01 +0000 (UTC) Received: from t460s.redhat.com (unknown [10.36.118.29]) by smtp.corp.redhat.com (Postfix) with ESMTP id 069C25C22C; Wed, 21 Aug 2019 09:22:59 +0000 (UTC) From: David Hildenbrand To: qemu-devel@nongnu.org Date: Wed, 21 Aug 2019 11:22:50 +0200 Message-Id: <20190821092252.26541-3-david@redhat.com> In-Reply-To: <20190821092252.26541-1-david@redhat.com> References: <20190821092252.26541-1-david@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.16 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.6.2 (mx1.redhat.com [10.5.110.64]); Wed, 21 Aug 2019 09:23:01 +0000 (UTC) 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 v1 2/4] s390x/tcg: Introduce probe_read_access() 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: Florian Weimer , Thomas Huth , David Hildenbrand , Cornelia Huck , Stefano Brivio , qemu-s390x@nongnu.org, Richard Henderson Errors-To: qemu-devel-bounces+patchwork-qemu-devel=patchwork.kernel.org@nongnu.org Sender: "Qemu-devel" Let's introduce a helper to probe read access (by actually reading a piece of data of every page) and add a comment why this might not be 100% safe in all scenarios. Once we actually run into that issue, we'll have to think of something else. Signed-off-by: David Hildenbrand Signed-off-by: David Hildenbrand --- target/s390x/internal.h | 2 ++ target/s390x/mem_helper.c | 34 ++++++++++++++++++++++++++++++++++ 2 files changed, 36 insertions(+) diff --git a/target/s390x/internal.h b/target/s390x/internal.h index c243fa725b..bdb833c525 100644 --- a/target/s390x/internal.h +++ b/target/s390x/internal.h @@ -354,6 +354,8 @@ void ioinst_handle_sal(S390CPU *cpu, uint64_t reg1, uintptr_t ra); /* mem_helper.c */ target_ulong mmu_real2abs(CPUS390XState *env, target_ulong raddr); +void probe_read_access(CPUS390XState *env, uint64_t addr, uint64_t len, + uintptr_t ra); void probe_write_access(CPUS390XState *env, uint64_t addr, uint64_t len, uintptr_t ra); diff --git a/target/s390x/mem_helper.c b/target/s390x/mem_helper.c index 7819aca15d..4e9d126e2c 100644 --- a/target/s390x/mem_helper.c +++ b/target/s390x/mem_helper.c @@ -2612,6 +2612,40 @@ uint32_t HELPER(cu42)(CPUS390XState *env, uint32_t r1, uint32_t r2, uint32_t m3) decode_utf32, encode_utf16); } +/* + * Make sure the read access is permitted and TLB entries are created. In + * very rare cases it might happen that the actual accesses might need + * new MMU translations. If the page tables were changed in between, we + * might still trigger a fault. However, this seems to barely happen, so we + * can ignore this for now. + */ +void probe_read_access(CPUS390XState *env, uint64_t addr, uint64_t len, + uintptr_t ra) +{ +#ifdef CONFIG_USER_ONLY + if (!guest_addr_valid(addr) || !guest_addr_valid(addr + len - 1) || + page_check_range(addr, len, PAGE_READ) < 0) { + s390_program_interrupt(env, PGM_ADDRESSING, ILEN_AUTO, ra); + } +#else + while (len) { + const uint64_t pagelen = -(addr | -TARGET_PAGE_MASK); + const uint64_t curlen = MIN(pagelen, len); + + cpu_ldub_data_ra(env, addr, ra); + addr = wrap_address(env, addr + curlen); + len -= curlen; + } +#endif +} + +/* + * Make sure the write access is permitted and TLB entries are created. In + * very rare cases it might happen that the actual accesses might need + * new MMU translations - especially, on LAP protected pages. If the page + * tables were changed in between, we might still trigger a fault. However, + * this seems to barely happen, so we can ignore this for now. + */ void probe_write_access(CPUS390XState *env, uint64_t addr, uint64_t len, uintptr_t ra) {