From patchwork Fri Feb 7 04:30:55 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: David Gibson X-Patchwork-Id: 11369753 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 135BD92A for ; Fri, 7 Feb 2020 04:32:13 +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 D23B622522 for ; Fri, 7 Feb 2020 04:32:11 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=gibson.dropbear.id.au header.i=@gibson.dropbear.id.au header.b="fBlJuoWp" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org D23B622522 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=gibson.dropbear.id.au Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+patchwork-qemu-devel=patchwork.kernel.org@nongnu.org Received: from localhost ([::1]:49904 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1izvJK-0008IV-V0 for patchwork-qemu-devel@patchwork.kernel.org; Thu, 06 Feb 2020 23:32:10 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]:44171) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1izvIO-00076Y-0Z for qemu-devel@nongnu.org; Thu, 06 Feb 2020 23:31:13 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1izvIM-00072r-HN for qemu-devel@nongnu.org; Thu, 06 Feb 2020 23:31:11 -0500 Received: from ozlabs.org ([2401:3900:2:1::2]:49209) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1izvIL-0005aK-8E; Thu, 06 Feb 2020 23:31:10 -0500 Received: by ozlabs.org (Postfix, from userid 1007) id 48DMmy4mzNz9sSJ; Fri, 7 Feb 2020 15:30:58 +1100 (AEDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=gibson.dropbear.id.au; s=201602; t=1581049858; bh=FtoKJ8jCKmMdy3M3VT71W+IwDmPpyCpOIPMGaQlg4zk=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=fBlJuoWpN8UFo9YhifQnaYQLF0NoCKl5MUmkPOSfpUmRfyysiuI0ePSLBmCq2UKSz vZB/La7d5PRIfr2E7zQ2jAGHhbcU5PYTE6LsR4T0DG5soLsisj+6WqOEE1hon6APwO xvQ0K/BsDXqwtvUZZ9OJgb6JsTJOs0Y/ekXyJ7rc= From: David Gibson To: groug@kaod.org, clg@kaod.org, pair@us.ibm.com Subject: [PATCH 2/2] spapr: Enable virtio iommu_platform=on by default Date: Fri, 7 Feb 2020 15:30:55 +1100 Message-Id: <20200207043055.218856-3-david@gibson.dropbear.id.au> X-Mailer: git-send-email 2.24.1 In-Reply-To: <20200207043055.218856-1-david@gibson.dropbear.id.au> References: <20200207043055.218856-1-david@gibson.dropbear.id.au> MIME-Version: 1.0 X-detected-operating-system: by eggs.gnu.org: Genre and OS details not recognized. X-Received-From: 2401:3900:2:1::2 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: mst@redhat.com, aik@ozlabs.ru, qemu-devel@nongnu.org, paulus@samba.org, mdroth@us.ibm.com, qemu-ppc@nongnu.org, David Gibson Errors-To: qemu-devel-bounces+patchwork-qemu-devel=patchwork.kernel.org@nongnu.org Sender: "Qemu-devel" Traditionally, virtio devices don't do DMA by the usual path on the guest platform. In particular they usually bypass any virtual IOMMU the guest has, using hypervisor magic to access untranslated guest physical addresses. There's now the optional iommu_platform flag which can tell virtio devices to use the platform's normal DMA path, including any IOMMUs. That flag was motiviated for the case of hardware virtio implementations, but there are other reasons to want it. Specifically, the fact that the virtio device doesn't use vIOMMU translation means that virtio devices are unsafe to pass to nested guests, or to use with VFIO userspace drivers inside the guest. This is particularly noticeable on the pseries platform which *always* has a guest-visible vIOMMU. Not using the normal DMA path also causes difficulties for the guest side driver when using the upcoming POWER Secure VMs (a.k.a. PEF). While it's theoretically possible to handle this on the guest side, it's really fiddly. Given the other problems with the non-translated virtio device, let's just enable vIOMMU translation for virtio devices by default in the pseries-5.0 (and later) machine types. Signed-off-by: David Gibson --- hw/ppc/spapr.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c index 216d3b34dc..78e031e80a 100644 --- a/hw/ppc/spapr.c +++ b/hw/ppc/spapr.c @@ -4518,6 +4518,7 @@ static void spapr_machine_5_0_class_options(MachineClass *mc) * default behaviour for virtio */ static GlobalProperty compat[] = { { TYPE_VIRTIO_PCI, "disable-legacy", "on", }, + { TYPE_VIRTIO_DEVICE, "iommu_platform", "on", }, }; compat_props_add(mc->compat_props, compat, G_N_ELEMENTS(compat)); @@ -4533,6 +4534,7 @@ static void spapr_machine_4_2_class_options(MachineClass *mc) SpaprMachineClass *smc = SPAPR_MACHINE_CLASS(mc); static GlobalProperty compat[] = { { TYPE_VIRTIO_PCI, "disable-legacy", "auto" }, + { TYPE_VIRTIO_DEVICE, "iommu_platform", "off", }, }; spapr_machine_5_0_class_options(mc);