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=-8.1 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,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 547C2C282DD for ; Thu, 9 Jan 2020 13:41:36 +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 1DA5520661 for ; Thu, 9 Jan 2020 13:41:36 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="BV9jFkni" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 1DA5520661 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]:60568 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1ipY47-0005Oe-4J for qemu-devel@archiver.kernel.org; Thu, 09 Jan 2020 08:41:35 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]:57118) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1ipY3K-0004Zu-S9 for qemu-devel@nongnu.org; Thu, 09 Jan 2020 08:40:48 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1ipY3I-0004Yy-AV for qemu-devel@nongnu.org; Thu, 09 Jan 2020 08:40:45 -0500 Received: from us-smtp-1.mimecast.com ([207.211.31.81]:51407 helo=us-smtp-delivery-1.mimecast.com) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1ipY3H-0004Vy-1W for qemu-devel@nongnu.org; Thu, 09 Jan 2020 08:40:43 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1578577241; 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=eeEwmEw42dqTy8R+7InpdtRvVQ9bBEs/nK5IY/kQ7TM=; b=BV9jFkniIoLMuZBL1CbOn9++kFjt4zaatWqe1MrynL3YL/u2rOP8JwxFeaVEufmVajwIcm VPLv0y2LhcMZl2t+dc2Dv4+c9bQNUBKbjXKEhZSY9fSsgcjExn3KC1HpjmY927qhPKcrC8 Vqs4j+v2Tc4Su8nu0CKs590s1OaIJzE= 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-73-rDXvTp8GMk2y8T9r5rj8pg-1; Thu, 09 Jan 2020 08:40:40 -0500 Received: from smtp.corp.redhat.com (int-mx07.intmail.prod.int.phx2.redhat.com [10.5.11.22]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id B5A1C10054E3 for ; Thu, 9 Jan 2020 13:40:39 +0000 (UTC) Received: from work-vm (unknown [10.36.118.29]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 850EE1000322; Thu, 9 Jan 2020 13:40:35 +0000 (UTC) Date: Thu, 9 Jan 2020 13:40:33 +0000 From: "Dr. David Alan Gilbert" To: "Michael S. Tsirkin" Subject: Re: [PATCH 2/2] hyperv/synic: Allocate as ram_device Message-ID: <20200109134033.GH6795@work-vm> References: <20200108135353.75471-1-dgilbert@redhat.com> <20200108135353.75471-3-dgilbert@redhat.com> <20200109064527-mutt-send-email-mst@kernel.org> <20200109120820.GB6795@work-vm> <20200109071454-mutt-send-email-mst@kernel.org> <20200109122237.GD6795@work-vm> <20200109080412-mutt-send-email-mst@kernel.org> <20200109132242.GF6795@work-vm> <20200109082726-mutt-send-email-mst@kernel.org> <20200109082810-mutt-send-email-mst@kernel.org> MIME-Version: 1.0 In-Reply-To: <20200109082810-mutt-send-email-mst@kernel.org> User-Agent: Mutt/1.13.0 (2019-11-30) X-Scanned-By: MIMEDefang 2.84 on 10.5.11.22 X-MC-Unique: rDXvTp8GMk2y8T9r5rj8pg-1 X-Mimecast-Spam-Score: 0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: quoted-printable Content-Disposition: inline X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] [fuzzy] X-Received-From: 207.211.31.81 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: jasowang@redhat.com, pbonzini@redhat.com, vkuznets@redhat.com, qemu-devel@nongnu.org Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" * Michael S. Tsirkin (mst@redhat.com) wrote: > On Thu, Jan 09, 2020 at 08:28:00AM -0500, Michael S. Tsirkin wrote: > > On Thu, Jan 09, 2020 at 01:22:42PM +0000, Dr. David Alan Gilbert wrote: > > > * Michael S. Tsirkin (mst@redhat.com) wrote: > > > > On Thu, Jan 09, 2020 at 12:22:37PM +0000, Dr. David Alan Gilbert wr= ote: > > > > > * Michael S. Tsirkin (mst@redhat.com) wrote: > > > > > > On Thu, Jan 09, 2020 at 12:08:20PM +0000, Dr. David Alan Gilber= t wrote: > > > > > > > * Michael S. Tsirkin (mst@redhat.com) wrote: > > > > > > > > On Wed, Jan 08, 2020 at 01:53:53PM +0000, Dr. David Alan Gi= lbert (git) wrote: > > > > > > > > > From: "Dr. David Alan Gilbert" > > > > > > > > >=20 > > > > > > > > > Mark the synic pages as ram_device so that they won't be = visible > > > > > > > > > to vhost. > > > > > > > > >=20 > > > > > > > > > Signed-off-by: Dr. David Alan Gilbert > > > > > > > >=20 > > > > > > > >=20 > > > > > > > > I think I disagree with this one. > > > > > > > > * A RAM device represents a mapping to a physical device, = such as to a PCI > > > > > > > > * MMIO BAR of an vfio-pci assigned device. The memory reg= ion may be mapped > > > > > > > > * into the VM address space and access to the region will = modify memory > > > > > > > > * directly. However, the memory region should not be incl= uded in a memory > > > > > > > > * dump (device may not be enabled/mapped at the time of th= e dump), and > > > > > > > > * operations incompatible with manipulating MMIO should be= avoided. Replaces > > > > > > > > * skip_dump flag. > > > > > > > >=20 > > > > > > > > Looks like an abuse of notation. > > > > > > >=20 > > > > > > > OK, it did feel a bit like that - any suggestions of another = way to do > > > > > > > it? > > > > > > > This clearly isn't normal RAM. > > > > > > >=20 > > > > > > > Dave > > > > > >=20 > > > > > > If it's just an optimization for vhost/postcopy/etc, then I thi= nk > > > > >=20 > > > > > Note it's not an optimisation; postcopy fails unless you can aggr= egate > > > > > the members of the hugepage. > > > > > And I think vhost-user will fail if you have too many sections - = and > > > > > the 16 sections from synic I think will blow the slots available. > > > >=20 > > > > Right, so both are internal reasons. > > > >=20 > > > > > > an API that says how this isn't normal ram would be ok. > > > > > > E.g. it's not DMA'd into? Then maybe _nodma? > > > > >=20 > > > > > Do we want a new memory_region_init for that or just to be able t= o add > > > > > a flag? > > > > >=20 > > > > > Dave > > > >=20 > > > > I think a flag API is preferable since this can apply to any kind o= f > > > > region. But can go either way, Paolo's the maintainer there. > > >=20 > > > (Copying Paolo in) > > > So what exactly does this flag mean; to me it's 'no vhost' - but is i= t > > > actually more general? > > >=20 > > > Dave > >=20 > > I think it's also handy for VFIO, that should skip it too. >=20 > BTW if it's "per cpu" then that is another way to put it. > Neither vfio nor vhost have a concept of cpu so neither > can support accessing per cpu things. In this case it's not really per-cpu in that sense; there's one of these regions per cpu, but I think each region is mapped by all cpus. Dave > >=20 > > > > > > > >=20 > > > > > > > >=20 > > > > > > > > > --- > > > > > > > > > hw/hyperv/hyperv.c | 14 ++++++++------ > > > > > > > > > 1 file changed, 8 insertions(+), 6 deletions(-) > > > > > > > > >=20 > > > > > > > > > diff --git a/hw/hyperv/hyperv.c b/hw/hyperv/hyperv.c > > > > > > > > > index da8ce82725..4de3ec411d 100644 > > > > > > > > > --- a/hw/hyperv/hyperv.c > > > > > > > > > +++ b/hw/hyperv/hyperv.c > > > > > > > > > @@ -95,12 +95,14 @@ static void synic_realize(DeviceState= *dev, Error **errp) > > > > > > > > > msgp_name =3D g_strdup_printf("synic-%u-msg-page", v= p_index); > > > > > > > > > eventp_name =3D g_strdup_printf("synic-%u-event-page= ", vp_index); > > > > > > > > > =20 > > > > > > > > > - memory_region_init_ram(&synic->msg_page_mr, obj, msg= p_name, > > > > > > > > > - sizeof(*synic->msg_page), &er= ror_abort); > > > > > > > > > - memory_region_init_ram(&synic->event_page_mr, obj, e= ventp_name, > > > > > > > > > - sizeof(*synic->event_page), &= error_abort); > > > > > > > > > - synic->msg_page =3D memory_region_get_ram_ptr(&synic= ->msg_page_mr); > > > > > > > > > - synic->event_page =3D memory_region_get_ram_ptr(&syn= ic->event_page_mr); > > > > > > > > > + synic->msg_page =3D qemu_memalign(qemu_real_host_pag= e_size, > > > > > > > > > + sizeof(*synic->msg_p= age)); > > > > > > > > > + synic->event_page =3D qemu_memalign(qemu_real_host_p= age_size, > > > > > > > > > + sizeof(*synic->eve= nt_page)); > > > > > > > > > + memory_region_init_ram_device_ptr(&synic->msg_page_m= r, obj, msgp_name, > > > > > > > > > + sizeof(*synic->msg_page), syn= ic->msg_page); > > > > > > > > > + memory_region_init_ram_device_ptr(&synic->event_page= _mr, obj, eventp_name, > > > > > > > > > + sizeof(*synic->event_page), s= ynic->event_page); > > > > > > > > > =20 > > > > > > > > > g_free(msgp_name); > > > > > > > > > g_free(eventp_name); > > > > > > > > > --=20 > > > > > > > > > 2.24.1 > > > > > > > >=20 > > > > > > > -- > > > > > > > Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK > > > > > >=20 > > > > > -- > > > > > Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK > > > >=20 > > > -- > > > Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK >=20 -- Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK