From patchwork Thu Mar 5 04:30:09 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: David Gibson X-Patchwork-Id: 11421169 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 D4930138D for ; Thu, 5 Mar 2020 04:31:38 +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 A617A208CD for ; Thu, 5 Mar 2020 04:31:38 +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="iFd7Ow6S" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org A617A208CD 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]:43206 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1j9iAb-0006Cm-7a for patchwork-qemu-devel@patchwork.kernel.org; Wed, 04 Mar 2020 23:31:37 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]:41207) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1j9i9O-0004xZ-7h for qemu-devel@nongnu.org; Wed, 04 Mar 2020 23:30:23 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1j9i9M-0003gp-Ks for qemu-devel@nongnu.org; Wed, 04 Mar 2020 23:30:21 -0500 Received: from bilbo.ozlabs.org ([203.11.71.1]:41203 helo=ozlabs.org) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1j9i9L-0003dT-NF; Wed, 04 Mar 2020 23:30:20 -0500 Received: by ozlabs.org (Postfix, from userid 1007) id 48XyTb2z1Fz9sQx; Thu, 5 Mar 2020 15:30:11 +1100 (AEDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=gibson.dropbear.id.au; s=201602; t=1583382611; bh=T/rehY0EMWJvQInxawyP6AROrA+skyuozSpPmM2NzLg=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=iFd7Ow6S3ofudvQ7TqM6HeMPDKOw9EgsBEmrWjhpjenF1x5ly0zgxk1nMEri1UlO3 f+bbT0VvsVyNRCQdpHW6Q8p1PBVQFQcDexaYRp5558v/pdfroB4rw5R8bD1uSDKqwC im8lvJpVsM2VWwffYpTMNzhL2pYOXz7bm3nkDQjs= From: David Gibson To: groug@kaod.org, pair@us.ibm.com, qemu-devel@nongnu.org, clg@kaod.org Subject: [PATCH v3 2/2] spapr: Enable virtio iommu_platform=on by default Date: Thu, 5 Mar 2020 15:30:09 +1100 Message-Id: <20200305043009.611636-3-david@gibson.dropbear.id.au> X-Mailer: git-send-email 2.24.1 In-Reply-To: <20200305043009.611636-1-david@gibson.dropbear.id.au> References: <20200305043009.611636-1-david@gibson.dropbear.id.au> MIME-Version: 1.0 X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] [fuzzy] X-Received-From: 203.11.71.1 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, 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. This does mean the new machine type will no longer support guest kernels older than 4.8, unless they have support for the virtio IOMMU_PLATFORM flag backported (which some distro kernels like RHEL7 do). 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 3cfc98ac61..5ef099536e 100644 --- a/hw/ppc/spapr.c +++ b/hw/ppc/spapr.c @@ -4575,6 +4575,7 @@ static void spapr_machine_latest_class_options(MachineClass *mc) */ static GlobalProperty compat[] = { { TYPE_VIRTIO_PCI, "disable-legacy", "on", }, + { TYPE_VIRTIO_DEVICE, "iommu_platform", "on", }, }; mc->alias = "pseries"; @@ -4622,6 +4623,7 @@ 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);