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=-2.4 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 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 EECAFC83004 for ; Wed, 29 Apr 2020 10:53:47 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id C884620731 for ; Wed, 29 Apr 2020 10:53:47 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="euDAA9Lc" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726678AbgD2Kxl (ORCPT ); Wed, 29 Apr 2020 06:53:41 -0400 Received: from us-smtp-delivery-1.mimecast.com ([205.139.110.120]:49375 "EHLO us-smtp-1.mimecast.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726426AbgD2Kxk (ORCPT ); Wed, 29 Apr 2020 06:53:40 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1588157618; 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=gj8fIWPa2CeyWIO94x3oC1OAlW1QijlTfsM+igUr3wo=; b=euDAA9LcrfMGYE5h3ub1k8IglrRuu15cOPI6Ub6HFqWpkbBoXlY0LrUYcvM9OEDMkIabo5 I33liij2mPD1WxDF80Jy7011Qi+xxpHs9CAa3Z99sFBojfNmN//TMTsgK4NUrTVgFpMixF uXsFrAjqgiC+cMvyAvLGgZxS/IdsI9c= Received: from mail-wr1-f69.google.com (mail-wr1-f69.google.com [209.85.221.69]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-8-vlJNJTntNBi2E2YBO4QQnA-1; Wed, 29 Apr 2020 06:53:36 -0400 X-MC-Unique: vlJNJTntNBi2E2YBO4QQnA-1 Received: by mail-wr1-f69.google.com with SMTP id f4so1530804wrp.14 for ; Wed, 29 Apr 2020 03:53:36 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:subject:to:cc:references:from:message-id:date :user-agent:mime-version:in-reply-to:content-language :content-transfer-encoding; bh=gj8fIWPa2CeyWIO94x3oC1OAlW1QijlTfsM+igUr3wo=; b=d+ITQMMt5Aua2ToREp/FiO+bC4pwahSZY5WHbT5X70/LJgm0c8cQwY9SULJteGWUTD dw02HEp0eMJpHJYqV0m6uyFSiJHQEPyGayD/KW552cem+k9ifmyOIU95lYFxB8tpfmiL jGtzjpO9xvPRn0VrTJww1goor/6Qbe+prf3vLrscjX7bvam8Uot6e5GrNPNp3h3yuCJi NPEw94O4Gc5XfQWIJO+eVIs+zlvEwxLMhqxUQipsK5xunPOIAf6/A76yA7wRB4P39nAb R883ARzbQA11ZRVUFXIaRNZufozyOotuhQ1+JK9ZsAh/SsHLMBXsK200e61znXoGnR/X AbDg== X-Gm-Message-State: AGi0Pubp5Zwr+geNc5G5tAQB+YEFHJMVvq4K0ld6GuK/G1ZegEgm8Lf8 i4OJCcXDvTF922nINFWaqqXXgVz9Cb+PWaTH4NWCjuFHgL+pWRHT949/Va8RyHPA+hzLXA/dOww PmEj7CqSFG9sG X-Received: by 2002:a05:600c:210b:: with SMTP id u11mr2726818wml.133.1588157615288; Wed, 29 Apr 2020 03:53:35 -0700 (PDT) X-Google-Smtp-Source: APiQypIpa3WPxNCQZbis9Xa4WSbuWEW/EHTeU5IyoGtjsiOXu0kixJo8iOl1+UjOd46HemWzC0wBrw== X-Received: by 2002:a05:600c:210b:: with SMTP id u11mr2726791wml.133.1588157615060; Wed, 29 Apr 2020 03:53:35 -0700 (PDT) Received: from ?IPv6:2001:b07:6468:f312:ac19:d1fb:3f5f:d54f? ([2001:b07:6468:f312:ac19:d1fb:3f5f:d54f]) by smtp.gmail.com with ESMTPSA id v7sm7016551wmg.3.2020.04.29.03.53.33 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 29 Apr 2020 03:53:34 -0700 (PDT) Subject: Re: [PATCH RFC 6/6] KVM: x86: Switch KVM guest to using interrupts for page ready APF delivery To: Vitaly Kuznetsov , x86@kernel.org, kvm@vger.kernel.org Cc: linux-kernel@vger.kernel.org, Andy Lutomirski , Thomas Gleixner , Ingo Molnar , Borislav Petkov , "H. Peter Anvin" , Sean Christopherson , Wanpeng Li , Jim Mattson References: <20200429093634.1514902-1-vkuznets@redhat.com> <20200429093634.1514902-7-vkuznets@redhat.com> From: Paolo Bonzini Message-ID: Date: Wed, 29 Apr 2020 12:53:33 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.6.0 MIME-Version: 1.0 In-Reply-To: <20200429093634.1514902-7-vkuznets@redhat.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org On 29/04/20 11:36, Vitaly Kuznetsov wrote: > + > + if (__this_cpu_read(apf_reason.enabled)) { > + reason = __this_cpu_read(apf_reason.reason); > + if (reason == KVM_PV_REASON_PAGE_READY) { > + token = __this_cpu_read(apf_reason.token); > + /* > + * Make sure we read 'token' before we reset > + * 'reason' or it can get lost. > + */ > + mb(); > + __this_cpu_write(apf_reason.reason, 0); > + kvm_async_pf_task_wake(token); > + } If tokens cannot be zero, could we avoid using reason for the page ready interrupt (and ultimately retire "reason" completely)? Paolo