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 DD368C282DD for ; Thu, 9 Jan 2020 13:23:51 +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 A63E8206ED for ; Thu, 9 Jan 2020 13:23:51 +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="Txil3ZSC" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org A63E8206ED 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]:60334 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1ipXmw-0003F7-RX for qemu-devel@archiver.kernel.org; Thu, 09 Jan 2020 08:23:50 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]:57667) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1ipXm1-0002JE-3V for qemu-devel@nongnu.org; Thu, 09 Jan 2020 08:22:54 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1ipXlz-0001F7-SZ for qemu-devel@nongnu.org; Thu, 09 Jan 2020 08:22:53 -0500 Received: from us-smtp-1.mimecast.com ([205.139.110.61]:51918 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 1ipXlz-0001BR-Ln for qemu-devel@nongnu.org; Thu, 09 Jan 2020 08:22:51 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1578576170; 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=ODvPi+qf+4ODJxeHeWFPmEwChCtB72VHLUirUBixah8=; b=Txil3ZSC7qzQGMWpPbOgMHL4Mcnz/7YIOvIzj7dSs1XdKicH1uGlIBipfjNazmtqI4gzII +LQQV56QyGSZxQGn06WnBERH7aDqPiuZTC4d2foCUG235+feQI9Vb1i1ZxwsiwxDt1mJEm jy111moyHVEeHoISOgat8jwUCMsSluc= 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-108-g2jQ55CzMxGwG1RKKxR_1w-1; Thu, 09 Jan 2020 08:22:49 -0500 Received: from smtp.corp.redhat.com (int-mx08.intmail.prod.int.phx2.redhat.com [10.5.11.23]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id BFA9F800D4E for ; Thu, 9 Jan 2020 13:22:48 +0000 (UTC) Received: from work-vm (unknown [10.36.118.29]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 8A960272A3; Thu, 9 Jan 2020 13:22:45 +0000 (UTC) Date: Thu, 9 Jan 2020 13:22:42 +0000 From: "Dr. David Alan Gilbert" To: "Michael S. Tsirkin" , pbonzini@redhat.com Subject: Re: [PATCH 2/2] hyperv/synic: Allocate as ram_device Message-ID: <20200109132242.GF6795@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> MIME-Version: 1.0 In-Reply-To: <20200109080412-mutt-send-email-mst@kernel.org> User-Agent: Mutt/1.13.0 (2019-11-30) X-Scanned-By: MIMEDefang 2.84 on 10.5.11.23 X-MC-Unique: g2jQ55CzMxGwG1RKKxR_1w-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: 205.139.110.61 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, 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 12:22:37PM +0000, Dr. David Alan Gilbert wrote: > > * Michael S. Tsirkin (mst@redhat.com) wrote: > > > On Thu, Jan 09, 2020 at 12:08:20PM +0000, Dr. David Alan Gilbert wrot= e: > > > > * Michael S. Tsirkin (mst@redhat.com) wrote: > > > > > On Wed, Jan 08, 2020 at 01:53:53PM +0000, Dr. David Alan Gilbert = (git) wrote: > > > > > > From: "Dr. David Alan Gilbert" > > > > > >=20 > > > > > > Mark the synic pages as ram_device so that they won't be visibl= e > > > > > > 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 a= s to a PCI > > > > > * MMIO BAR of an vfio-pci assigned device. The memory region ma= y be mapped > > > > > * into the VM address space and access to the region will modify= memory > > > > > * directly. However, the memory region should not be included i= n a memory > > > > > * dump (device may not be enabled/mapped at the time of the dump= ), and > > > > > * operations incompatible with manipulating MMIO should be avoid= ed. 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 think > >=20 > > Note it's not an optimisation; postcopy fails unless you can aggregate > > 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 to add > > a flag? > >=20 > > Dave >=20 > I think a flag API is preferable since this can apply to any kind of > region. But can go either way, Paolo's the maintainer there. (Copying Paolo in) So what exactly does this flag mean; to me it's 'no vhost' - but is it actually more general? Dave > > > > >=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", vp_inde= x); > > > > > > eventp_name =3D g_strdup_printf("synic-%u-event-page", vp_= index); > > > > > > =20 > > > > > > - memory_region_init_ram(&synic->msg_page_mr, obj, msgp_name= , > > > > > > - sizeof(*synic->msg_page), &error_ab= ort); > > > > > > - memory_region_init_ram(&synic->event_page_mr, obj, eventp_= 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(&synic->ev= ent_page_mr); > > > > > > + synic->msg_page =3D qemu_memalign(qemu_real_host_page_size= , > > > > > > + sizeof(*synic->msg_page)); > > > > > > + synic->event_page =3D qemu_memalign(qemu_real_host_page_si= ze, > > > > > > + sizeof(*synic->event_pag= e)); > > > > > > + memory_region_init_ram_device_ptr(&synic->msg_page_mr, obj= , msgp_name, > > > > > > + sizeof(*synic->msg_page), synic->ms= g_page); > > > > > > + memory_region_init_ram_device_ptr(&synic->event_page_mr, o= bj, eventp_name, > > > > > > + sizeof(*synic->event_page), synic->= 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