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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 30A50C19F28 for ; Wed, 3 Aug 2022 17:33:56 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236577AbiHCRdy (ORCPT ); Wed, 3 Aug 2022 13:33:54 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:42146 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S238310AbiHCRdu (ORCPT ); Wed, 3 Aug 2022 13:33:50 -0400 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id 995845727A for ; Wed, 3 Aug 2022 10:33:49 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1659548028; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=+5QAlTD0yVo3KUlmnd7w4NlvzNv43A/mFCjPCFZegUM=; b=Nk38WKu5DsyfQcDtXoMj9DCJ8w75rjyG1Di9whCV9hr3seZXd0z+pY7JFi0ET6j7vV5rGV qVmzpr6HB/H+oVSUme7RNsu0KMOXp0UtpPbJL91mmr6BTVhEbYOBZgBNMLOLUiukENP2RW 0vss2p120iR0+1nLNpZQmVKyoiuyH3Y= Received: from mail-wm1-f72.google.com (mail-wm1-f72.google.com [209.85.128.72]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-101-HiAS59uBOkqL4MXJz728cw-1; Wed, 03 Aug 2022 13:33:47 -0400 X-MC-Unique: HiAS59uBOkqL4MXJz728cw-1 Received: by mail-wm1-f72.google.com with SMTP id m4-20020a7bce04000000b003a386063752so382263wmc.1 for ; Wed, 03 Aug 2022 10:33:47 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=content-transfer-encoding:in-reply-to:from:references:cc:to :content-language:subject:user-agent:mime-version:date:message-id :x-gm-message-state:from:to:cc; bh=+5QAlTD0yVo3KUlmnd7w4NlvzNv43A/mFCjPCFZegUM=; b=ONcFQiWGZGtiKf+7fhccBou1kQfu6VZIz/mUPzxHpNRyVu3VvlfsKFP9rElcOG+5If Eytw9UrzRtywSwrB5UFZ94Ww8RZhQasbO0WeYDqvj2B8DuX+QU4J+hxk7GCv4tf8EZnW lsrVDTDp+SIXjecM586o2YSzQLPd4UaCm0K+ssAnwFagxvScTRxDd1iz6NpnRdH0ltZG y2IPOY9PhWtXJspCVqnTQ/PR/XyhTuWMkoN0pjcwDVDWTpvi9MMBNnLIw+c3+9sG058o VyFHRCp0ykp/3ynWvPBtQKQOz9GTwredE4qz/WmUrhmz5nzO1NznjH/6pO3cGHdghxEB PK+g== X-Gm-Message-State: ACgBeo3oYAfqXpN/s5Vb6TSmrV1mW7ZuCa/kR7TxTOE1p43Rdeq9RHXf OS8faa1E5fQpj7DgayLgDQDxK18nB5XfcwB5IwhTwn8k/A+QrvfmU9kUkC5kEWmcLiHVa82UvKl DPZISky7hmOUZzCbQK5h6qDvM X-Received: by 2002:a5d:5a1a:0:b0:21f:a9b:62c6 with SMTP id bq26-20020a5d5a1a000000b0021f0a9b62c6mr16526613wrb.20.1659548026122; Wed, 03 Aug 2022 10:33:46 -0700 (PDT) X-Google-Smtp-Source: AA6agR7NS7DQx36jQ4hn2m0a7zi3iwiyfGu90K9fZ7IwCQxglzQUf40ZJcqhUqtqEInch/OWlH0/yQ== X-Received: by 2002:a5d:5a1a:0:b0:21f:a9b:62c6 with SMTP id bq26-20020a5d5a1a000000b0021f0a9b62c6mr16526595wrb.20.1659548025917; Wed, 03 Aug 2022 10:33:45 -0700 (PDT) Received: from ?IPV6:2001:b07:add:ec09:c399:bc87:7b6c:fb2a? ([2001:b07:add:ec09:c399:bc87:7b6c:fb2a]) by smtp.googlemail.com with ESMTPSA id m15-20020adffa0f000000b0021e5f32ade7sm18593005wrr.68.2022.08.03.10.33.40 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 03 Aug 2022 10:33:45 -0700 (PDT) Message-ID: <899e4d3d-e086-71a5-38f9-17e85ce11ea4@redhat.com> Date: Wed, 3 Aug 2022 19:33:39 +0200 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.11.0 Subject: Re: [PATCH] x86/fpu: Allow PKRU to be (once again) written by ptrace. Content-Language: en-US To: Ingo Molnar , Kyle Huey Cc: Dave Hansen , Thomas Gleixner , Borislav Petkov , Ingo Molnar , x86@kernel.org, "H. Peter Anvin" , Andy Lutomirski , Peter Zijlstra , linux-kernel@vger.kernel.org, Robert O'Callahan , David Manouchehri , kvm@vger.kernel.org, stable@vger.kernel.org References: <20220731050342.56513-1-khuey@kylehuey.com> From: Paolo Bonzini In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 8/3/22 19:25, Ingo Molnar wrote: > Ok - allowing ptrace to set the full 32 bits of the PKRU register seems OK > then, and is 100% equivalent to using WRPKRU, right? So there's no implicit > masking/clearing of bits depending on how many keys are available, or other > details where WRPKRU might differ from a pure 32-bit per thread write, > correct? Yes, it's the same. Paolo