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=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS 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 BCBC5C12002 for ; Wed, 21 Jul 2021 11:09:44 +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 8C45D60D07 for ; Wed, 21 Jul 2021 11:09:43 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 8C45D60D07 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+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.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:MIME-Version:References:In-Reply-To: Subject:Cc:To:From:Message-ID:Date:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=oQT/6WUaZdZuPWsSQgS95EVeFCsIEgvnPzznfQxuVQU=; b=f3rDStP94oe3Wk /JYgBOv09QfUorHfPtH+bZnL1kWJLwAdG28e5KT5K6lBwhRzq+ZotXbRTCgr7PIIPqRBMQ5/6YGey LEEviJutJyLLpj4KqEtYVNDv1DnFbHyflXbb7SCv7XZZ7/M7ZuXfDLWNmqkzE2dODO23CiM6wXzOM 2RpakiHZV3FHgoY16xU4NlbowdBvBoRp/R3NAHJBOdYPWN+2SBJ6udjVE3mccnr+kq/YnesZqVNeT zZ5NOFCflr+j8cEMBTYks8GY7ltoTtWnx05aE96vVdPSmspmA3zgm75IIiAj4w++fRxv5y8vMh+34 CgaUBXyMREO3EDQfqXmg==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1m6A5R-00FO0H-CM; Wed, 21 Jul 2021 11:08:25 +0000 Received: from mail.kernel.org ([198.145.29.99]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1m6A5N-00FNz8-Da for linux-arm-kernel@lists.infradead.org; Wed, 21 Jul 2021 11:08:22 +0000 Received: from disco-boy.misterjones.org (disco-boy.misterjones.org [51.254.78.96]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 0A05960720; Wed, 21 Jul 2021 11:08:21 +0000 (UTC) Received: from sofa.misterjones.org ([185.219.108.64] helo=why.misterjones.org) by disco-boy.misterjones.org with esmtpsa (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.94.2) (envelope-from ) id 1m6A5K-00F2Hh-S3; Wed, 21 Jul 2021 12:08:19 +0100 Date: Wed, 21 Jul 2021 12:08:18 +0100 Message-ID: <87a6mf3owt.wl-maz@kernel.org> From: Marc Zyngier To: Sergey Senozhatsky Cc: Joel Fernandes , Will Deacon , Suleiman Souhlal , linux-arm-kernel@lists.infradead.org, kvmarm@lists.cs.columbia.edu, linux-kernel@vger.kernel.org, virtualization@lists.linux-foundation.org Subject: Re: [PATCHv2 4/4] arm64: add host pv-vcpu-state support In-Reply-To: References: <20210709043713.887098-1-senozhatsky@chromium.org> <20210709043713.887098-5-senozhatsky@chromium.org> <874kcz33g5.wl-maz@kernel.org> <87h7go2h69.wl-maz@kernel.org> User-Agent: Wanderlust/2.15.9 (Almost Unreal) SEMI-EPG/1.14.7 (Harue) FLIM-LB/1.14.9 (=?UTF-8?B?R29qxY0=?=) APEL-LB/10.8 EasyPG/1.0.0 Emacs/27.1 (x86_64-pc-linux-gnu) MULE/6.0 (HANACHIRUSATO) MIME-Version: 1.0 (generated by SEMI-EPG 1.14.7 - "Harue") X-SA-Exim-Connect-IP: 185.219.108.64 X-SA-Exim-Rcpt-To: senozhatsky@chromium.org, joelaf@google.com, will@kernel.org, suleiman@google.com, linux-arm-kernel@lists.infradead.org, kvmarm@lists.cs.columbia.edu, linux-kernel@vger.kernel.org, virtualization@lists.linux-foundation.org X-SA-Exim-Mail-From: maz@kernel.org X-SA-Exim-Scanned: No (on disco-boy.misterjones.org); SAEximRunCond expanded to false X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20210721_040821_537881_84A303D8 X-CRM114-Status: GOOD ( 23.48 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Wed, 21 Jul 2021 11:38:40 +0100, Sergey Senozhatsky wrote: > > On (21/07/21 09:40), Marc Zyngier wrote: > > > > > > Can that be cured by just checking vcpu->preempted before calling > > > kvm_update_vcpu_preempted() ? > > > > It isn't obvious to me that this is the right thing to do. > > vcpu->preempted is always updated on sched-out from the preempt > > notifier if the vcpu was on the run-queue, so my guess is that it will > > always be set when switching to another task. > > > > What you probably want is to check whether the vcpu is blocked by > > introspecting the wait-queue with: > > > > scuwait_active(kvm_arch_vcpu_get_wait(vcpu) > > > > which will tell you whether you are blocking or not. We are already > > using a similar construct for arming a background timer in this case. > > Can we examine if vcpu->run->exit_reason == WFE/WFI and avoid setting > preempted state if so? We never go back to userspace for WFI/WFE, so no reason to populate the run structure. Checking for the blocked state is the right thing to do, and we already have the primitive for this. Just use it. M. -- Without deviation from the norm, progress is not possible. _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel