From mboxrd@z Thu Jan 1 00:00:00 1970 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=-0.8 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS autolearn=ham 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 5E058C2BC61 for ; Mon, 29 Oct 2018 08:55:38 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 0E84C2084A for ; Mon, 29 Oct 2018 08:55:37 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="axiUYSjK" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 0E84C2084A Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=gmail.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729481AbeJ2RnR (ORCPT ); Mon, 29 Oct 2018 13:43:17 -0400 Received: from mail-wm1-f65.google.com ([209.85.128.65]:35823 "EHLO mail-wm1-f65.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729429AbeJ2RnR (ORCPT ); Mon, 29 Oct 2018 13:43:17 -0400 Received: by mail-wm1-f65.google.com with SMTP id q12-v6so4353774wmq.0 for ; Mon, 29 Oct 2018 01:55:34 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=zBxGQcGPRP0ykXDQYo3v2UheTzL3gJScMOFXPFIUvdw=; b=axiUYSjK05QQVbT6PcDWXOb1F7zqokHDuUsxdQm4Ko7dqCdmurH07LlYDWPxojSrXv 9M3Yb11Sk8r5QjragnJ0V5H8MuC170+AZ7YCo6NKimb2jpeFWhFcjjCa1aTdZfo0yoD6 lZby+pGTQ33bVUI/KT9vONZ1XMUDBXqjENb3ejMBe1noHtC3mREn2/bszgq9G84n7Bpf YgVpRZMrSJe30jSHXo23iDfflLYwJh5fHPoWLmw1joCtd/Fd/TxgFKRqBt+Tb+8m/vCq zakNEx/ZUuIAn9sIpEywBoBeXY5A+MwYrgP2VB/WY+JSndNdnD5fsPHuBgSRHhW8qv9P zZOg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=zBxGQcGPRP0ykXDQYo3v2UheTzL3gJScMOFXPFIUvdw=; b=QKbj8uYI0k+iQ9wwE5AmPVTfZwZnuLxOe71NGiUswI+HwJBot8Hwe8CLOt2XtFwiFR Z9q7ZXz6c+bI14xnqgzd+zrJQ/E8TJBI0uVnHz3KT7lzoWL8D6jWzHIkCu7w164Wx675 gYG9g5kX0rAJDt7Z3vctkccqVJg7nZc8AXycnkDqb4q8baplsd1jTgS4OZB64C4cB5oL qj+v7MZPWlQWaZP6AxVwCjCWhYUsa9oCVqKbNToTIWc7jQ0YjgMtykxu7FMRLFouCrOz UjIL+sO+McpnCEad+KS+X8GptUIX3naxuKTDULPiblOzK1PjJXY1xyUjPPGUoMYubFqa S9hw== X-Gm-Message-State: AGRZ1gIHHodbuHZm8Vwj9+giwXQWJTsEjkLBf9Hs/QXUi0uTI+vveUTB vssOMGxs0wGDZIQZkPrkZyWCz26PIfQyp0heoKM= X-Google-Smtp-Source: AJdET5evFZ+0gPV4oLVUppIARA9wPD2IbrieSyvPFvxe9OFjcM1q0nQA5k0HbtdKK0/6RJQ82LuzyOmeBs/gBBMuAp8= X-Received: by 2002:a1c:38c1:: with SMTP id f184-v6mr10373684wma.24.1540803334146; Mon, 29 Oct 2018 01:55:34 -0700 (PDT) MIME-Version: 1.0 References: <20181026195146.9C7C1136@viggo.jf.intel.com> <0e5fd8bc-0b18-ea88-ed95-ec81a44d0783@intel.com> <20181029063626.GD128403@gmail.com> In-Reply-To: <20181029063626.GD128403@gmail.com> From: Daniel Micay Date: Mon, 29 Oct 2018 04:55:07 -0400 Message-ID: Subject: Re: [PATCH 1/2] x86/pkeys: copy pkey state at fork() To: Ingo Molnar Cc: Andy Lutomirski , Dave Hansen , Dave Hansen , kernel list , Thomas Gleixner , Ingo Molnar , Borislav Petkov , "H . Peter Anvin" , X86 ML , Peter Zijlstra , Michael Ellerman , Will Deacon , Andy Lutomirski , jroedel@suse.de Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Yeah, a no-op pkey_alloc flag tied to this patch to provide a way to detect if pkey state is preserved on fork, since kernels without the patch would report EINVAL. Something like PKEY_ASSERT_FORK_INHERIT_STATE would make sense. Otherwise, it's going to be quite painful to adopt this in userspace software without kernel version checks. Most software can't accept causing a crash / abort after forking in environments not applying all the stable kernel patches, or in fresh OS installs that aren't fully updated + rebooted yet.