Received: by 2002:a25:1985:0:0:0:0:0 with SMTP id 127csp4028705ybz; Mon, 20 Apr 2020 14:11:13 -0700 (PDT) X-Google-Smtp-Source: APiQypKhAJfXFSSqP4Fn2gJy4EVpDcFE/YCRGrz+hFW+kkk+uB4QeFk7oMeulKbaXRxr27Pi8Q7G X-Received: by 2002:a17:907:9481:: with SMTP id dm1mr18584930ejc.9.1587417073238; Mon, 20 Apr 2020 14:11:13 -0700 (PDT) ARC-Seal: i=1; a=rsa-sha256; t=1587417073; cv=none; d=google.com; s=arc-20160816; b=RkTDt1DtAACkXsi0D6w6w2dw9eN5BFpEG4A6ZJsZOA3RtHmgpGuPWStZCOIHOnZZfq l09SJEfYF1bMLr/p0PZzbSbzbkBLTUp2ylUh5bSBDCTSlkq6Zx/g/olex300SXivJmjZ MBD9NBiuIYeMfBYUHrbJfjQszue0YLyKt+h0r+kNmEA7WYCFnEuJj3ScsCsAm/q41TZ0 VF8OyMefT+bBgCe5XWKO9H7bpxHf650UUTm7zOnF7Z+hkt8s41eaoTqxRjfT4pPbmlPt ygvyhTVe6ArpYY7/e1KkvgsJ58cqvJFu8amSQUN5dFnGInZCKVT7xlmWXKTg0I+zAE7P t1lg== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=list-id:precedence:sender:content-transfer-encoding :content-language:in-reply-to:mime-version:user-agent:date :message-id:from:references:cc:to:subject:dkim-signature; bh=T/IYN1616yr1SA6PkPQ11e2tZILCIQKcMMBO70ZP5s8=; b=qflCPjZvyUKhyk7jITePtbhl4uHIhEO26d3YXY+vflDpL4AU6VL9VC1bx2Gp0qcQz8 EC+YtSdsmFF4vhwBgCizg+mYgiqj1FcHguhVCusOIX8U/yy9QQd2nH48eDECAj2NK9xl MUoOrsPNgAiBMkYQuFsB/L+e3InnDCUCeQKYa1hw3n8d/3hPbC2+B8jx/qob0gHOEThR 9WCMDL7Kg8UUnn1jlsLWPsBl+PASlAH2WKNskWLyCHKxg6jBJfFHWJygq3ucnl7uOD+W +6r/PD/k8k+xtYeXzXoF6FMMfBmeXzPI/yhczU8tZnidmHXbiL9fQgYNgwzrhlpLVrIY QoUQ== ARC-Authentication-Results: i=1; mx.google.com; dkim=pass header.i=@redhat.com header.s=mimecast20190719 header.b=CGCbe8fz; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=redhat.com Return-Path: Received: from vger.kernel.org (vger.kernel.org. [23.128.96.18]) by mx.google.com with ESMTP id u10si250410ejt.145.2020.04.20.14.10.49; Mon, 20 Apr 2020 14:11:13 -0700 (PDT) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18; Authentication-Results: mx.google.com; dkim=pass header.i=@redhat.com header.s=mimecast20190719 header.b=CGCbe8fz; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=redhat.com Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727889AbgDTVHc (ORCPT + 99 others); Mon, 20 Apr 2020 17:07:32 -0400 Received: from us-smtp-2.mimecast.com ([207.211.31.81]:47296 "EHLO us-smtp-delivery-1.mimecast.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1727768AbgDTVHb (ORCPT ); Mon, 20 Apr 2020 17:07:31 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1587416850; 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=T/IYN1616yr1SA6PkPQ11e2tZILCIQKcMMBO70ZP5s8=; b=CGCbe8fzQqnaIQZtyklrdw7vBPMKqA5O95HUs38Zxpc9e7o4BDksmv4kPamME92LXrr2V8 pd83oknFwFEt5EQxe4wTtmHfW9Lyoz9KJHyIC9PiiBH7Q6sh3fU7TLcJ2fv2Hv5K7NCrHm mjZjV2awCYkAtw9NdHT9HEiy6l0lOjU= Received: from mail-wm1-f71.google.com (mail-wm1-f71.google.com [209.85.128.71]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-321-5eEsuILKMbeb7ItiefifNg-1; Mon, 20 Apr 2020 17:07:28 -0400 X-MC-Unique: 5eEsuILKMbeb7ItiefifNg-1 Received: by mail-wm1-f71.google.com with SMTP id o26so456910wmh.1 for ; Mon, 20 Apr 2020 14:07:27 -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=T/IYN1616yr1SA6PkPQ11e2tZILCIQKcMMBO70ZP5s8=; b=WHxGw+YNh0TicW0nJ+hFEcfLNlCHhkj2v6OOgz2dY89L3KrLr9I0p2pt/uPqWOgGAL bjkWTYdoIBdazqc76lP5PAJrtMLe4Y3YomsD4Bs23Z5TwyXqewLQCF5A2vzEnmhjKO0y WdcSoskdZ0hmEwf54o6DsRwwl7UU9gGfxXIW/dbroN7Ids2AgDZmplD6zmWO++vG9Ou9 eJ4z3fmZU7Ey/imJdWrckIFRXWFAGIYsJyJDRnA55tcyXcMOIdG9o9zoVlodydTvF2mS RxrTJuL8bKt5JcJFn0BlE7P5fWWjbZNiz11N4onMJpBccX0dFodQ30fhELFj76a2LrWA aAgg== X-Gm-Message-State: AGi0PuanePso8Kzbr6YDec950uATw66d2j6I85xxY3kKuJfxXuyIRkjM YWGuChj/mDuejojvJgdszcz8CCvvCP1+VQ6BeVpStSnr+RDF7vzr7BvkwBBB2T5xr+MgEDs8PEK 1CVFDQAXfjzI5XaJOsrMd7Vd9 X-Received: by 2002:adf:dec9:: with SMTP id i9mr17364162wrn.197.1587416846887; Mon, 20 Apr 2020 14:07:26 -0700 (PDT) X-Received: by 2002:adf:dec9:: with SMTP id i9mr17364149wrn.197.1587416846652; Mon, 20 Apr 2020 14:07:26 -0700 (PDT) Received: from ?IPv6:2001:b07:6468:f312:5c18:5523:c13e:fa9f? ([2001:b07:6468:f312:5c18:5523:c13e:fa9f]) by smtp.gmail.com with ESMTPSA id b191sm809910wmd.39.2020.04.20.14.07.25 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 20 Apr 2020 14:07:26 -0700 (PDT) Subject: Re: [PATCH] kvm: add capability for halt polling To: Jon Cargille , Vitaly Kuznetsov Cc: David Matlack , Sean Christopherson , Wanpeng Li , Jim Mattson , Joerg Roedel , Thomas Gleixner , Ingo Molnar , Borislav Petkov , "H. Peter Anvin" , x86@kernel.org, kvm@vger.kernel.org, linux-kernel@vger.kernel.org References: <20200417221446.108733-1-jcargill@google.com> <87d083td9f.fsf@vitty.brq.redhat.com> From: Paolo Bonzini Message-ID: <02848f20-ecf9-550b-9b55-0260b05f6ecd@redhat.com> Date: Mon, 20 Apr 2020 23:07:24 +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: 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 20/04/20 20:47, Jon Cargille wrote: > Great question, Vitaly. We actually implemented this as a per-VCPU property > initially; however, our user-space implementation was only using it to apply > the same value to all VCPUs, so we later simplified it on the advice of > Jim Mattson. If there is a consensus for this to go in as per-VCPU rather > than per-VM, I'm happy to submit that way instead. The per-VM version did > end up looking simpler, IMO. Yeah, I am not sure what the usecase would be for per-vCPU halt polling. You could perhaps disable halt polling for vCPUs that are not placed on isolated physical CPUs (devoting those vCPUs to housekeeping), but it seems to me that this would be quite hard to get right. But in that case you would probably prefer to disable HLT vmexits completely, rather than use halt polling. Paolo