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=-2.3 required=3.0 tests=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 F3364C0650F for ; Mon, 5 Aug 2019 12:01:52 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id C6029206A2 for ; Mon, 5 Aug 2019 12:01:52 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728532AbfHEMBv (ORCPT ); Mon, 5 Aug 2019 08:01:51 -0400 Received: from mail-wr1-f66.google.com ([209.85.221.66]:42848 "EHLO mail-wr1-f66.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727553AbfHEMBv (ORCPT ); Mon, 5 Aug 2019 08:01:51 -0400 Received: by mail-wr1-f66.google.com with SMTP id x1so34243509wrr.9 for ; Mon, 05 Aug 2019 05:01:50 -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:openpgp:message-id :date:user-agent:mime-version:in-reply-to:content-language :content-transfer-encoding; bh=2nagADd5jn/PM+jdv3CsfqiPWcm300QiQQSn7jI3dpY=; b=S3a7S4jb79fQNyXjFY1vCMLLjibDjksG5NTGtdYlFy8uA+44Wza+f3hcAlwS6HyI0k jDoMfo1VGsJ+i1y7QiE7Rv7pFngNrxhlcNlbfTggOHfQWDKWGraxAJYm7PsJv284TOu5 nVqZ6d3ZWALkamVYl5TJvE/UVnu4ulXogf8HVX0aCRal4zmUgp7CZU5cxut33T0uhv6K 7v6CffM4X/pqH3JkzFssYMjMfCQFoFInOL2pIn5ADC8rDpBM2P0Z9dRhX//MqwwWd9B7 degclYLM4zQIrfn8hqZxaesCuWjCh68zD0KK8zKbjp4vCROwqImnjevxRCSWywxYgl2/ KAgw== X-Gm-Message-State: APjAAAX0/enFaA0gVHahYsf1gLZEuklRnTMJy7AA12u+MPR0KV48US5m mDMYh43Jjs91ySEdF/+u1MBqqKPWCJM= X-Google-Smtp-Source: APXvYqxE67uGRsevI1zEKu6WcCvy7LGAqb+5YSaaPfzVS62blyzVnMo0SSHLm4YD1CuRcd1v857erg== X-Received: by 2002:a5d:6508:: with SMTP id x8mr42706085wru.310.1565006509205; Mon, 05 Aug 2019 05:01:49 -0700 (PDT) Received: from [192.168.178.40] ([151.21.165.91]) by smtp.gmail.com with ESMTPSA id c1sm192489759wrh.1.2019.08.05.05.01.47 (version=TLS1_3 cipher=AEAD-AES128-GCM-SHA256 bits=128/128); Mon, 05 Aug 2019 05:01:48 -0700 (PDT) Subject: Re: [RFC PATCH v2 07/19] RISC-V: KVM: Implement KVM_GET_ONE_REG/KVM_SET_ONE_REG ioctls To: Anup Patel , Christian Borntraeger Cc: Anup Patel , Palmer Dabbelt , Paul Walmsley , Radim K , Daniel Lezcano , Thomas Gleixner , Atish Patra , Alistair Francis , Damien Le Moal , Christoph Hellwig , "kvm@vger.kernel.org" , "linux-riscv@lists.infradead.org" , "linux-kernel@vger.kernel.org" References: <20190802074620.115029-1-anup.patel@wdc.com> <20190802074620.115029-8-anup.patel@wdc.com> From: Paolo Bonzini Openpgp: preference=signencrypt Message-ID: <09417197-36e8-718f-f106-29466ef406e3@redhat.com> Date: Mon, 5 Aug 2019 14:01:47 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.8.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 05/08/19 13:56, Anup Patel wrote: > We will certainly explore sync_regs interface. Reducing exits to user-space > will definitely help. sync_regs does not reduce exits to userspace, it reduces ioctls from userspace but there is a real benefit only if userspace actually makes many syscalls for each vmexit. Paolo