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=-2.4 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,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 03C07C33C9E for ; Tue, 28 Jan 2020 11:00:50 +0000 (UTC) Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (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 C41562467B for ; Tue, 28 Jan 2020 11:00:49 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="L3wxap78" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org C41562467B Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:57078 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1iwObw-0006pw-U8 for qemu-devel@archiver.kernel.org; Tue, 28 Jan 2020 06:00:48 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]:54252) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1iwOad-0005C1-I9 for qemu-devel@nongnu.org; Tue, 28 Jan 2020 05:59:28 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1iwOac-0000ya-LR for qemu-devel@nongnu.org; Tue, 28 Jan 2020 05:59:27 -0500 Received: from us-smtp-delivery-1.mimecast.com ([205.139.110.120]:58994 helo=us-smtp-1.mimecast.com) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1iwOac-0000y1-Hv for qemu-devel@nongnu.org; Tue, 28 Jan 2020 05:59:26 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1580209166; 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=9dSYi4dvn0AY+/YeHWr7iYWeBW00lmhzZ7LvW95TaqA=; b=L3wxap78vDfsk70tnJvbSRL0BUILKA/t99laARV0seKnpFk9G8LyEsB1SXeF+zS6cJT7Vx 4JBLIfknpRGOFxTLHs6K5i86TT0kXq6xsVG5amOX6UVsr9AFRhu4wERoPMfkZrm9BTIVnb ivSPJneYNKNztnJMiOFYtVaUIxorE1Q= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-386-tq_6zD0ZP6yVktb4oXzkmA-1; Tue, 28 Jan 2020 05:59:21 -0500 Received: from smtp.corp.redhat.com (int-mx03.intmail.prod.int.phx2.redhat.com [10.5.11.13]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 3A612100550E; Tue, 28 Jan 2020 10:59:20 +0000 (UTC) Received: from [10.36.116.37] (ovpn-116-37.ams2.redhat.com [10.36.116.37]) by smtp.corp.redhat.com (Postfix) with ESMTPS id C96578887E; Tue, 28 Jan 2020 10:59:17 +0000 (UTC) Subject: Re: [question] hw/arm/virt: about the default gic-version in accelerated mode To: Peter Maydell References: From: Auger Eric Message-ID: <516da1db-a959-95b4-2d24-cafcd7136bcd@redhat.com> Date: Tue, 28 Jan 2020 11:59:14 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.4.0 MIME-Version: 1.0 In-Reply-To: Content-Language: en-US X-Scanned-By: MIMEDefang 2.79 on 10.5.11.13 X-MC-Unique: tq_6zD0ZP6yVktb4oXzkmA-1 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-Received-From: 205.139.110.120 X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Andrew Jones , qemu-arm , qemu list , "Dr. David Alan Gilbert" Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" Hi Peter, On 1/28/20 11:52 AM, Peter Maydell wrote: > On Tue, 28 Jan 2020 at 10:47, Auger Eric wrote: >> When arm virt machine is run in accelerated mode with "-cpu host >> -machine virt", the default gic version is 2. >> >> I understand the rationale with TCG where we don't have MSI ITS >> emulation along with GICv3 so we need to choose GICv2 to get GICv2M >> functionality. >> >> However in KVM mode, I would have expected to see the host GIC probed to >> set the same version on guest. Indeed most of our HW now have GICv3 >> without GICv2 compat mode so our default values lead to weird traces: >> >> " >> qemu-system-aarch64: PMU: KVM_SET_DEVICE_ATTR: Invalid argument >> qemu-system-aarch64: failed to set irq for PMU >> " >> >> I would like to propose a patch to improve those errors and also suggest >> a hint. But I also wanted to know whether you would accept to change the >> default value with KVM and choose the host version instead of 2. For TCG >> we would keep v2. > > As with the -cpu option, the default is there for command > line backward compatibility primarily. Even if we had > better support for MSI ITS emulation we'd still leave > the default at GICv2. > > If you want "do the best you can, regardless of accelerator" > that is "-cpu max -machine gic-version=max". OK that's understood. So I will just try to improve the above traces. Thanks Eric > > thanks > -- PMM >