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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]:54314 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1kI7wF-0007Pw-5O for qemu-devel@archiver.kernel.org; Tue, 15 Sep 2020 06:11:51 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:44986) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1kI7uz-0006lz-E3 for qemu-devel@nongnu.org; Tue, 15 Sep 2020 06:10:33 -0400 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:31991) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_CBC_SHA1:256) (Exim 4.90_1) (envelope-from ) id 1kI7us-0008OX-UZ for qemu-devel@nongnu.org; Tue, 15 Sep 2020 06:10:33 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1600164625; 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=WtrAHA50eWoIhE7jJ5AdGa3m2fvFNMhD0wQGYELrCPo=; b=FDnQ2YWQrv/ndLImcOSzyO/RAyFpttW3Qf1jaIadU2NMR/jsB9WvHvFn3fxJcl1djq+H+T nqUk2YXSuQ7QQUkTC4mxkv/Bvjn9JeQSPTnu+QAOjdq4q6wnECiz9sJ7RVkRbwNiwa4LB0 owJbiWKOqlQsgQ0rdX8hHDsRedTj+1s= 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-143-tSQPFBaLPu-rnNn3aFWnnQ-1; Tue, 15 Sep 2020 06:10:24 -0400 X-MC-Unique: tSQPFBaLPu-rnNn3aFWnnQ-1 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 8DB28191E2AB; Tue, 15 Sep 2020 10:10:21 +0000 (UTC) Received: from gondolin (ovpn-113-4.ams2.redhat.com [10.36.113.4]) by smtp.corp.redhat.com (Postfix) with ESMTP id 5F9FE81C6B; Tue, 15 Sep 2020 10:10:13 +0000 (UTC) Date: Tue, 15 Sep 2020 12:10:10 +0200 From: Cornelia Huck To: Philippe =?UTF-8?B?TWF0aGlldS1EYXVkw6k=?= Subject: Re: [PATCH v2 1/3] vfio: Find DMA available capability Message-ID: <20200915121010.117fa931.cohuck@redhat.com> In-Reply-To: References: <1600122570-12941-1-git-send-email-mjrosato@linux.ibm.com> <1600122570-12941-2-git-send-email-mjrosato@linux.ibm.com> Organization: Red Hat GmbH MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.13 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=cohuck@redhat.com X-Mimecast-Spam-Score: 0.002 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable Received-SPF: pass client-ip=216.205.24.124; envelope-from=cohuck@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-detected-operating-system: by eggs.gnu.org: First seen = 2020/09/15 02:10:32 X-ACL-Warn: Detected OS = Linux 2.2.x-3.x [generic] [fuzzy] X-Spam_score_int: -38 X-Spam_score: -3.9 X-Spam_bar: --- X-Spam_report: (-3.9 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-1.792, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H5=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=unavailable autolearn_force=no X-Spam_action: no action 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: thuth@redhat.com, Matthew Rosato , pmorel@linux.ibm.com, schnelle@linux.ibm.com, qemu-s390x@nongnu.org, david@redhat.com, qemu-devel@nongnu.org, pasic@linux.ibm.com, borntraeger@de.ibm.com, alex.williamson@redhat.com, rth@twiddle.net Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On Tue, 15 Sep 2020 08:14:24 +0200 Philippe Mathieu-Daud=C3=A9 wrote: > Hi Matthew, >=20 > On 9/15/20 12:29 AM, Matthew Rosato wrote: > > The underlying host may be limiting the number of outstanding DMA > > requests for type 1 IOMMU. Add helper functions to check for the > > DMA available capability and retrieve the current number of DMA > > mappings allowed. > >=20 > > Signed-off-by: Matthew Rosato > > --- > > hw/vfio/common.c | 37 +++++++++++++++++++++++++++++++++++= ++ > > include/hw/vfio/vfio-common.h | 2 ++ > > 2 files changed, 39 insertions(+) (...) > > +bool vfio_get_info_dma_avail(struct vfio_iommu_type1_info *info, > > + unsigned int *avail) > > +{ > > + struct vfio_info_cap_header *hdr; > > + struct vfio_iommu_type1_info_dma_avail *cap; > > + > > + /* If the capability cannot be found, assume no DMA limiting */ > > + hdr =3D vfio_get_iommu_type1_info_cap(info, > > + VFIO_IOMMU_TYPE1_INFO_DMA_AVAI= L); > > + if (hdr =3D=3D NULL || avail =3D=3D NULL) { =20 >=20 > If you expect the caller to use avail=3DNULL, then why > return false when there is available information? I agree; if the purpose of this function is to check if limiting is in place and only optionally return the actual limit, we should return true for hdr !=3D NULL and avail =3D=3D NULL. >=20 > > + return false; > > + } > > + > > + cap =3D (void *) hdr; > > + *avail =3D cap->avail; > > + return true; > > +} > > + > > static int vfio_setup_region_sparse_mmaps(VFIORegion *region, > > struct vfio_region_info *inf= o) > > { (...)