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=-5.5 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=ham 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 1985BC0650F for ; Thu, 8 Aug 2019 15:50:01 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id E16D82173E for ; Thu, 8 Aug 2019 15:50:00 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="Fr4QZh0f" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org E16D82173E Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20170209; h=Sender: Content-Transfer-Encoding:Content-Type:Cc:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:Date: Message-ID:From:References:To:Subject:Reply-To:Content-ID:Content-Description :Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=Z9hLJAxoJC0g2ptSStYAHpN5rDoyuvN+/Ya2trXrtAw=; b=Fr4QZh0fHTb2bI J5amPG6VQ77Vv+2u1029385o6EcLpujlrhrYrD6VBbkveq4fCgrU1y7Iy5Oh+Y0KUHd42hrAN03Kg MTG4t9wqCO7Oaq+f1Fk2QkMCE+LFB974G3WSS2p0U4KXR+KZXC3mqhadvQpoHJDSxY5kPzgfUDZ2E FRzJEP0f+1R7OPPsJIEonn3xl3EUMEZirnVaVq49m0Z6YYEFuGU81Uhczt7fly2k8cX+qfMOerCx8 dsHloBBUTOTM84Rxc8tGjDXczfbXmIgyU5vVNCxhY+rmGPSEhjQ2QiYgSgMbFBDYXyjVe4cysQruC v/5wGuYwgvuE4ilPmReQ==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.92 #3 (Red Hat Linux)) id 1hvkfo-0001mO-TK; Thu, 08 Aug 2019 15:49:52 +0000 Received: from foss.arm.com ([217.140.110.172]) by bombadil.infradead.org with esmtp (Exim 4.92 #3 (Red Hat Linux)) id 1hvkfl-0001lg-VC for linux-arm-kernel@lists.infradead.org; Thu, 08 Aug 2019 15:49:51 +0000 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 593D01596; Thu, 8 Aug 2019 08:49:48 -0700 (PDT) Received: from [10.1.197.61] (usa-sjc-imap-foss1.foss.arm.com [10.121.207.14]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id A5E283F706; Thu, 8 Aug 2019 08:49:46 -0700 (PDT) Subject: Re: [PATCH 9/9] arm64: Retrieve stolen time as paravirtualized guest To: Steven Price References: <20190802145017.42543-1-steven.price@arm.com> <20190802145017.42543-10-steven.price@arm.com> <20190804105353.5e9824dc@why> From: Marc Zyngier Organization: Approximate Message-ID: <7108a70b-dafd-507b-8509-f4a092ef24af@kernel.org> Date: Thu, 8 Aug 2019 16:49:45 +0100 User-Agent: Mozilla/5.0 (X11; Linux aarch64; rv:60.0) Gecko/20100101 Thunderbird/60.8.0 MIME-Version: 1.0 In-Reply-To: Content-Language: en-US X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20190808_084950_051400_A5744B18 X-CRM114-Status: GOOD ( 13.76 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: kvm@vger.kernel.org, =?UTF-8?B?UmFkaW0gS3LEjW3DocWZ?= , Catalin Marinas , Suzuki K Pouloze , linux-doc@vger.kernel.org, Russell King , linux-kernel@vger.kernel.org, James Morse , linux-arm-kernel@lists.infradead.org, Paolo Bonzini , Will Deacon , kvmarm@lists.cs.columbia.edu, Julien Thierry Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org On 08/08/2019 16:29, Steven Price wrote: > On 04/08/2019 10:53, Marc Zyngier wrote: >> On Fri, 2 Aug 2019 15:50:17 +0100 >> Steven Price wrote: >> >>> Enable paravirtualization features when running under a hypervisor >>> supporting the PV_TIME_ST hypercall. >>> >>> For each (v)CPU, we ask the hypervisor for the location of a shared >>> page which the hypervisor will use to report stolen time to us. We set >>> pv_time_ops to the stolen time function which simply reads the stolen >>> value from the shared page for a VCPU. We guarantee single-copy >>> atomicity using READ_ONCE which means we can also read the stolen >>> time for another VCPU than the currently running one while it is >>> potentially being updated by the hypervisor. >>> >>> Signed-off-by: Steven Price >>> --- >>> arch/arm64/kernel/Makefile | 1 + >>> arch/arm64/kernel/kvm.c | 155 +++++++++++++++++++++++++++++++++++++ [...] >>> +static int __init kvm_guest_init(void) >>> +{ >>> + int ret = 0; >>> + >>> + if (!has_kvm_steal_clock()) >>> + return 0; >>> + >>> + ret = kvm_arm_init_stolen_time(); >>> + if (ret) >>> + return ret; >>> + >>> + pv_ops.time.steal_clock = kvm_steal_clock; >>> + >>> + static_key_slow_inc(¶virt_steal_enabled); >>> + if (steal_acc) >>> + static_key_slow_inc(¶virt_steal_rq_enabled); >>> + >>> + pr_info("using stolen time PV\n"); >>> + >>> + return 0; >>> +} >>> +early_initcall(kvm_guest_init); >> >> Is there any reason why we wouldn't directly call into this rather than >> using an initcall? > > I'm not sure where the direct call would go - any pointers? I'd be temped to say arch/arm64/kernel/time.c:time_init(), provided that there is no issue with the CPU hotplug lock (I remember hitting that a while ago). M. -- Jazz is not dead, it just smells funny... _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel