From patchwork Wed Sep 23 16:41:26 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Dan Williams X-Patchwork-Id: 309278 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-3.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI, SPF_HELO_NONE, SPF_PASS autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id C2E1DC2D0A8 for ; Wed, 23 Sep 2020 16:59:49 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 6F7BD21BE5 for ; Wed, 23 Sep 2020 16:59:49 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726674AbgIWQ7s (ORCPT ); Wed, 23 Sep 2020 12:59:48 -0400 Received: from mga04.intel.com ([192.55.52.120]:12857 "EHLO mga04.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726667AbgIWQ7s (ORCPT ); Wed, 23 Sep 2020 12:59:48 -0400 IronPort-SDR: txJ/YYDS6ouwuY3uQgkkdYWP26pi7gtg+SeHMPaPpc0y5O/Ax+4X+00i6d15q7bMFGkoTVTUQZ 0d8YdzXOiluA== X-IronPort-AV: E=McAfee;i="6000,8403,9753"; a="158346693" X-IronPort-AV: E=Sophos;i="5.77,293,1596524400"; d="scan'208";a="158346693" X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from fmsmga006.fm.intel.com ([10.253.24.20]) by fmsmga104.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 23 Sep 2020 09:59:47 -0700 IronPort-SDR: Uk3FpZWtjC6MxaY2DpATud/gCLigyWCbeA2NfdUXbwu2fTZl13//C7v+skd5M53i4aVDYwi05+ R65xu4Hv6T4Q== X-IronPort-AV: E=Sophos;i="5.77,293,1596524400"; d="scan'208";a="511067966" Received: from dwillia2-desk3.jf.intel.com (HELO dwillia2-desk3.amr.corp.intel.com) ([10.54.39.16]) by fmsmga006-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 23 Sep 2020 09:59:47 -0700 Subject: [PATCH v9 0/2] Renovate memcpy_mcsafe with copy_mc_to_{user, kernel} From: Dan Williams To: mingo@redhat.com Cc: Tony Luck , Vivek Goyal , Peter Zijlstra , Linus Torvalds , Alexander Viro , Borislav Petkov , stable@vger.kernel.org, x86@kernel.org, "H. Peter Anvin" , Thomas Gleixner , Andy Lutomirski , Paul Mackerras , Benjamin Herrenschmidt , Erwin Tsaur , Michael Ellerman , Mikulas Patocka , Arnaldo Carvalho de Melo , 0day robot , tglx@linutronix.de, x86@kernel.org, linux-nvdimm@lists.01.org, linux-kernel@vger.kernel.org, jack@suse.cz Date: Wed, 23 Sep 2020 09:41:26 -0700 Message-ID: <160087928642.3520.17063139768910633998.stgit@dwillia2-desk3.amr.corp.intel.com> User-Agent: StGit/0.18-3-g996c MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org Changes since v8 [1]: - Rebase on v5.9-rc6 - Fix a performance regression in the x86 copy_mc_to_user() implementation that was duplicating copies in the "fragile" case. - Refreshed the cover letter. [1]: http://lore.kernel.org/r/159630255616.3143511.18110575960499749012.stgit@dwillia2-desk3.amr.corp.intel.com --- The motivations to go rework memcpy_mcsafe() are that the benefit of doing slow and careful copies is obviated on newer CPUs, and that the current opt-in list of cpus to instrument recovery is broken relative to those cpus. There is no need to keep an opt-in list up to date on an ongoing basis if pmem/dax operations are instrumented for recovery by default. With recovery enabled by default the old "mcsafe_key" opt-in to careful copying can be made a "fragile" opt-out. Where the "fragile" list takes steps to not consume poison across cachelines. The discussion with Linus made clear that the current "_mcsafe" suffix was imprecise to a fault. The operations that are needed by pmem/dax are to copy from a source address that might throw #MC to a destination that may write-fault, if it is a user page. So copy_to_user_mcsafe() becomes copy_mc_to_user() to indicate the separate precautions taken on source and destination. copy_mc_to_kernel() is introduced as a version that does not expect write-faults on the destination, but is still prepared to abort with an error code upon taking #MC. These patches have received a kbuild-robot build success notification across 114 configs, the rebase to v5.9-rc6 did not encounter any conflicts, and the merge with tip/master is conflict-free. --- Dan Williams (2): x86, powerpc: Rename memcpy_mcsafe() to copy_mc_to_{user,kernel}() x86/copy_mc: Introduce copy_mc_generic() arch/powerpc/Kconfig | 2 arch/powerpc/include/asm/string.h | 2 arch/powerpc/include/asm/uaccess.h | 40 +++-- arch/powerpc/lib/Makefile | 2 arch/powerpc/lib/copy_mc_64.S | 4 arch/x86/Kconfig | 2 arch/x86/Kconfig.debug | 2 arch/x86/include/asm/copy_mc_test.h | 75 +++++++++ arch/x86/include/asm/mcsafe_test.h | 75 --------- arch/x86/include/asm/string_64.h | 32 ---- arch/x86/include/asm/uaccess.h | 21 +++ arch/x86/include/asm/uaccess_64.h | 20 -- arch/x86/kernel/cpu/mce/core.c | 8 - arch/x86/kernel/quirks.c | 9 - arch/x86/lib/Makefile | 1 arch/x86/lib/copy_mc.c | 65 ++++++++ arch/x86/lib/copy_mc_64.S | 165 ++++++++++++++++++++ arch/x86/lib/memcpy_64.S | 115 -------------- arch/x86/lib/usercopy_64.c | 21 --- drivers/md/dm-writecache.c | 15 +- drivers/nvdimm/claim.c | 2 drivers/nvdimm/pmem.c | 6 - include/linux/string.h | 9 - include/linux/uaccess.h | 9 + include/linux/uio.h | 10 + lib/Kconfig | 7 + lib/iov_iter.c | 43 +++-- tools/arch/x86/include/asm/mcsafe_test.h | 13 -- tools/arch/x86/lib/memcpy_64.S | 115 -------------- tools/objtool/check.c | 5 - tools/perf/bench/Build | 1 tools/perf/bench/mem-memcpy-x86-64-lib.c | 24 --- tools/testing/nvdimm/test/nfit.c | 48 +++--- .../testing/selftests/powerpc/copyloops/.gitignore | 2 tools/testing/selftests/powerpc/copyloops/Makefile | 6 - .../selftests/powerpc/copyloops/copy_mc_64.S | 1 .../selftests/powerpc/copyloops/memcpy_mcsafe_64.S | 1 37 files changed, 452 insertions(+), 526 deletions(-) rename arch/powerpc/lib/{memcpy_mcsafe_64.S => copy_mc_64.S} (98%) create mode 100644 arch/x86/include/asm/copy_mc_test.h delete mode 100644 arch/x86/include/asm/mcsafe_test.h create mode 100644 arch/x86/lib/copy_mc.c create mode 100644 arch/x86/lib/copy_mc_64.S delete mode 100644 tools/arch/x86/include/asm/mcsafe_test.h delete mode 100644 tools/perf/bench/mem-memcpy-x86-64-lib.c create mode 120000 tools/testing/selftests/powerpc/copyloops/copy_mc_64.S delete mode 120000 tools/testing/selftests/powerpc/copyloops/memcpy_mcsafe_64.S base-commit: ba4f184e126b751d1bffad5897f263108befc780