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=-5.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_SANE_1 autolearn=unavailable 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 F1E7BC3A5A7 for ; Tue, 3 Sep 2019 09:19:05 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id CD23C22D6D for ; Tue, 3 Sep 2019 09:19:05 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728509AbfICJTC (ORCPT ); Tue, 3 Sep 2019 05:19:02 -0400 Received: from szxga06-in.huawei.com ([45.249.212.32]:38466 "EHLO huawei.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1727077AbfICJTB (ORCPT ); Tue, 3 Sep 2019 05:19:01 -0400 Received: from DGGEMS411-HUB.china.huawei.com (unknown [172.30.72.59]) by Forcepoint Email with ESMTP id 33C4E53355E7BE0D137C; Tue, 3 Sep 2019 17:18:58 +0800 (CST) Received: from [127.0.0.1] (10.184.12.158) by DGGEMS411-HUB.china.huawei.com (10.3.19.211) with Microsoft SMTP Server id 14.3.439.0; Tue, 3 Sep 2019 17:18:50 +0800 Subject: Re: [PATCH v4 05/10] KVM: arm64: Support stolen time reporting via shared structure To: Steven Price , Marc Zyngier , "Will Deacon" , , CC: , , Catalin Marinas , , Russell King , Paolo Bonzini References: <20190830084255.55113-1-steven.price@arm.com> <20190830084255.55113-6-steven.price@arm.com> From: Zenghui Yu Message-ID: Date: Tue, 3 Sep 2019 17:14:18 +0800 User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:64.0) Gecko/20100101 Thunderbird/64.0 MIME-Version: 1.0 In-Reply-To: <20190830084255.55113-6-steven.price@arm.com> Content-Type: text/plain; charset="utf-8"; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit X-Originating-IP: [10.184.12.158] X-CFilter-Loop: Reflected Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org On 2019/8/30 16:42, Steven Price wrote: > Implement the service call for configuring a shared structure between a > VCPU and the hypervisor in which the hypervisor can write the time > stolen from the VCPU's execution time by other tasks on the host. > > The hypervisor allocates memory which is placed at an IPA chosen by user > space. It seems that no allocation happens in the hypervisor code. User space will do it instead? > The hypervisor then updates the shared structure using > kvm_put_guest() to ensure single copy atomicity of the 64-bit value > reporting the stolen time in nanoseconds. > > Whenever stolen time is enabled by the guest, the stolen time counter is > reset. > > The stolen time itself is retrieved from the sched_info structure > maintained by the Linux scheduler code. We enable SCHEDSTATS when > selecting KVM Kconfig to ensure this value is meaningful. > > Signed-off-by: Steven Price Thanks, zenghui