From nobody Sun Feb 8 23:41:00 2026 Delivered-To: importer@patchew.org Received-SPF: pass (zoho.com: domain of redhat.com designates 209.132.183.28 as permitted sender) client-ip=209.132.183.28; envelope-from=libvir-list-bounces@redhat.com; helo=mx1.redhat.com; Authentication-Results: mx.zohomail.com; spf=pass (zoho.com: domain of redhat.com designates 209.132.183.28 as permitted sender) smtp.mailfrom=libvir-list-bounces@redhat.com; dmarc=pass(p=none dis=none) header.from=redhat.com Return-Path: Received: from mx1.redhat.com (mx1.redhat.com [209.132.183.28]) by mx.zohomail.com with SMTPS id 1521203930319856.6305803549026; Fri, 16 Mar 2018 05:38:50 -0700 (PDT) Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.phx2.redhat.com [10.5.11.14]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id CC5677FDE5; Fri, 16 Mar 2018 12:38:48 +0000 (UTC) Received: from colo-mx.corp.redhat.com (colo-mx02.intmail.prod.int.phx2.redhat.com [10.5.11.21]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 991B15D72D; Fri, 16 Mar 2018 12:38:48 +0000 (UTC) Received: from lists01.pubmisc.prod.ext.phx2.redhat.com (lists01.pubmisc.prod.ext.phx2.redhat.com [10.5.19.33]) by colo-mx.corp.redhat.com (Postfix) with ESMTP id 6515E65D15; Fri, 16 Mar 2018 12:38:48 +0000 (UTC) Received: from smtp.corp.redhat.com (int-mx03.intmail.prod.int.rdu2.redhat.com [10.11.54.3]) by lists01.pubmisc.prod.ext.phx2.redhat.com (8.13.8/8.13.8) with ESMTP id w2GCc7LJ026882 for ; Fri, 16 Mar 2018 08:38:07 -0400 Received: by smtp.corp.redhat.com (Postfix) id B9E5510B00AF; Fri, 16 Mar 2018 12:38:07 +0000 (UTC) Received: from beluga.usersys.redhat.com (unknown [10.43.2.166]) by smtp.corp.redhat.com (Postfix) with ESMTP id 4451A10B00B1; Fri, 16 Mar 2018 12:38:07 +0000 (UTC) From: Erik Skultety To: libvir-list@redhat.com Date: Fri, 16 Mar 2018 13:37:54 +0100 Message-Id: In-Reply-To: References: In-Reply-To: References: X-Scanned-By: MIMEDefang 2.78 on 10.11.54.3 X-loop: libvir-list@redhat.com Cc: Erik Skultety Subject: [libvirt] [PATCH v2 2/2] qemu: hostdev: Fix the error on VM start with an mdev when IOMMU is off X-BeenThere: libvir-list@redhat.com X-Mailman-Version: 2.1.12 Precedence: junk List-Id: Development discussions about the libvirt library & tools List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Sender: libvir-list-bounces@redhat.com Errors-To: libvir-list-bounces@redhat.com X-Scanned-By: MIMEDefang 2.79 on 10.5.11.14 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.27]); Fri, 16 Mar 2018 12:38:49 +0000 (UTC) X-ZohoMail: RSF_0 Z_629925259 SPT_0 Content-Type: text/plain; charset="utf-8" Commit b4c2ac8d56 made a false assumption that IOMMU support necessary for an mdev device to be assigned to a VM. Unlike direct PCI assignment, IOMMU support is not needed for mediated devices, as the physical parent device provides the IOMMU isolation, therefore, simply checking for VFIO presence is enough to successfully start a VM. Luckily, this issue is not serious, since as of yet, libvirt mandates mdevs to be pre-created prior to a domain's launch - if it is, everything does work smoothly, because the parent device will ensure the iommu groups we try to access exist. However, if the mdev didn't exist, one would see the following error: "unsupported configuration: Mediated host device assignment requires VFIO support" The error msg above is simply wrong and doesn't even reflect the IOMMU reality, so after applying this patch one would rather hit the following error: "device not found: mediated device '' not found" Signed-off-by: Erik Skultety --- src/qemu/qemu_hostdev.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) diff --git a/src/qemu/qemu_hostdev.c b/src/qemu/qemu_hostdev.c index 73d26f4c6..afe445d4e 100644 --- a/src/qemu/qemu_hostdev.c +++ b/src/qemu/qemu_hostdev.c @@ -330,9 +330,14 @@ qemuHostdevPrepareMediatedDevices(virQEMUDriverPtr dri= ver, int nhostdevs) { virHostdevManagerPtr hostdev_mgr =3D driver->hostdevMgr; - bool supportsVFIO =3D qemuHostdevHostSupportsPassthroughVFIO(); + bool supportsVFIO; size_t i; + /* Checking for VFIO only is fine with mdev, as IOMMU isolation is ach= ieved + * by the physical parent device. + */ + supportsVFIO =3D virFileExists("/dev/vfio/vfio"); + for (i =3D 0; i < nhostdevs; i++) { if (hostdevs[i]->mode =3D=3D VIR_DOMAIN_HOSTDEV_MODE_SUBSYS && hostdevs[i]->source.subsys.type =3D=3D VIR_DOMAIN_HOSTDEV_SUBS= YS_TYPE_MDEV) { -- 2.13.6 -- libvir-list mailing list libvir-list@redhat.com https://www.redhat.com/mailman/listinfo/libvir-list