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 mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 2C0B8C4332F for ; Wed, 13 Oct 2021 15:05:56 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 0ECAE61053 for ; Wed, 13 Oct 2021 15:05:56 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231372AbhJMPH5 (ORCPT ); Wed, 13 Oct 2021 11:07:57 -0400 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:21106 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229514AbhJMPHz (ORCPT ); Wed, 13 Oct 2021 11:07:55 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1634137552; 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=ZUvBAsWmgQbw3yBugnmSYIWYxF7ZgSd0vwpJHIAZn0U=; b=dJQe2y5r5yc4Fk37tbT5yHKW1uVCITy3KIXrZIAz9wEKrSdf+4APe07nOCOUFXznsy5dQC JumST4XW0+9+BtOX10x47MJcDqsGys6ivJ8PZVe5jBbDO8OQLmgCW4ubxlOKAdiOc+MyXv +g6lJBm9eIvyWG9e6dVHRWETn8bYKoc= Received: from mail-ed1-f69.google.com (mail-ed1-f69.google.com [209.85.208.69]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-573-6nXNyKZ3OgiYM8YUl3uxJg-1; Wed, 13 Oct 2021 11:05:50 -0400 X-MC-Unique: 6nXNyKZ3OgiYM8YUl3uxJg-1 Received: by mail-ed1-f69.google.com with SMTP id f4-20020a50e084000000b003db585bc274so2483265edl.17 for ; Wed, 13 Oct 2021 08:05:50 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:message-id:date:mime-version:user-agent:subject :content-language:to:cc:references:from:in-reply-to :content-transfer-encoding; bh=ZUvBAsWmgQbw3yBugnmSYIWYxF7ZgSd0vwpJHIAZn0U=; b=Uag5CtyP117+OaYKEX84K5xbgAUSP//Vr1hktNyG4ZAxoWzBgTY7jFHXzkuI3ZcTbv znLaMsoU3VgcqFlIK+PUoEh2cfV2kuTuSXhRpVAqWpiCLkdDN9W6EnLSYg/LyDKx3eir kcxH5VWhUN3fWUc0BM9G7sJEKTObZtu1B1oSEYzWsHatyefBom4lAxujdMWatVBaSUAb tEisUjWv9YMyRdGiXYnCCRUKJdq1eeMUPiapS09UKCEowIBvXGg73AbcTQnH6DdsL0Yj UpelUjxmZYwxydMybT/BCjvV8FXyD3COZ7fi4g4u8amZ+EUubNGq6ll7kDVJrV21xIun Y1Zw== X-Gm-Message-State: AOAM5328iBwhaqGudsZFloDtw6Gj+LF1abL/hpgDnAQXtiD35aEcuHPE kP/K9cVOJt84wFh38JVN0bFBQalpfna1hmAixfvCX+ol97sNIl4niyqs3Umy6Q6Q2mDiCCkWaCv e1ZvT4majQ3uWORZcNTV0UMNY X-Received: by 2002:a17:906:39d8:: with SMTP id i24mr23058eje.49.1634137549552; Wed, 13 Oct 2021 08:05:49 -0700 (PDT) X-Google-Smtp-Source: ABdhPJz/xDpJNxyPHo5beDcIqc5nv7j7IdDRzLCPacTEVEqeKPisHZnDBc+2PPNDdWlNmtFXLDR97w== X-Received: by 2002:a17:906:39d8:: with SMTP id i24mr23026eje.49.1634137549301; Wed, 13 Oct 2021 08:05:49 -0700 (PDT) Received: from ?IPV6:2001:b07:6468:f312:c8dd:75d4:99ab:290a? ([2001:b07:6468:f312:c8dd:75d4:99ab:290a]) by smtp.gmail.com with ESMTPSA id se12sm6949370ejb.88.2021.10.13.08.05.45 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 13 Oct 2021 08:05:48 -0700 (PDT) Message-ID: <59c1dbc5-95f6-c592-d85c-c13a64bbee55@redhat.com> Date: Wed, 13 Oct 2021 17:05:44 +0200 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.1.0 Subject: Re: [patch 13/31] x86/fpu: Move KVMs FPU swapping to FPU core Content-Language: en-US To: Andy Lutomirski , "Liu, Jing2" , Thomas Gleixner , Linux Kernel Mailing List Cc: the arch/x86 maintainers , "Bae, Chang Seok" , Dave Hansen , Arjan van de Ven , kvm list , "Nakajima, Jun" , Jing Liu , Sean Christopherson References: <20211011215813.558681373@linutronix.de> <20211011223611.069324121@linutronix.de> <8a5762ab-18d5-56f8-78a6-c722a2f387c5@redhat.com> <0962c143-2ff9-f157-d258-d16659818e80@redhat.com> <10a8868e-eb85-4043-a5ad-96c03d9b0abb@www.fastmail.com> From: Paolo Bonzini In-Reply-To: <10a8868e-eb85-4043-a5ad-96c03d9b0abb@www.fastmail.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 13/10/21 16:59, Andy Lutomirski wrote: >> >> Thinking more about it, #NM only has to be trapped if XCR0 enables >> a dynamic feature. In other words, the guest value of XFD can be >> limited to (host_XFD|guest_XFD) & guest_XCR0. This avoids that >> KVM unnecessarily traps for old guests that use CR0.TS. >> > You could simplify this by allocating the state the first time XCR0 > enables the feature in question. > > (This is how regular non-virt userspace*should* work too, but it > looks like I’ve probably been outvoted on that front…) Good point, you could do that too and do the work on the XCR0 vmexit instead of #NM. Paolo