From patchwork Fri Jun 19 02:06:02 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: David Gibson X-Patchwork-Id: 11613113 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 035A314E3 for ; Fri, 19 Jun 2020 02:06:20 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id D506120888 for ; Fri, 19 Jun 2020 02:06:19 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=gibson.dropbear.id.au header.i=@gibson.dropbear.id.au header.b="Vb47zuH8" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729386AbgFSCGP (ORCPT ); Thu, 18 Jun 2020 22:06:15 -0400 Received: from bilbo.ozlabs.org ([203.11.71.1]:46503 "EHLO ozlabs.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729211AbgFSCGO (ORCPT ); Thu, 18 Jun 2020 22:06:14 -0400 Received: by ozlabs.org (Postfix, from userid 1007) id 49p2GT4QHRz9sT9; Fri, 19 Jun 2020 12:06:09 +1000 (AEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=gibson.dropbear.id.au; s=201602; t=1592532369; bh=mtzkVC37cD70gZZRJwitgnHn1rAt12wP3H2B7h801OA=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=Vb47zuH8AeY0Rt1D1epCfmen+R/9FWcG0PkfOkDWsRDehfFaIxDcwBec2zAstER0V /0Apuld5o9ZDSaPq1QqKcZbGISKS9FbMqq0/+k/lQLY+pNvSmSzjBGjQ64shXj9yHz +gVGN2ZqMpWC9V1jeUFXD56PQwZf68UyPuEhsKHE= From: David Gibson To: qemu-devel@nongnu.org, brijesh.singh@amd.com, pair@us.ibm.com, pbonzini@redhat.com, dgilbert@redhat.com, frankja@linux.ibm.com Cc: Marcel Apfelbaum , kvm@vger.kernel.org, qemu-ppc@nongnu.org, mst@redhat.com, mdroth@linux.vnet.ibm.com, Richard Henderson , cohuck@redhat.com, pasic@linux.ibm.com, Eduardo Habkost , David Gibson , qemu-s390x@nongnu.org, david@redhat.com Subject: [PATCH v3 9/9] host trust limitation: Alter virtio default properties for protected guests Date: Fri, 19 Jun 2020 12:06:02 +1000 Message-Id: <20200619020602.118306-10-david@gibson.dropbear.id.au> X-Mailer: git-send-email 2.26.2 In-Reply-To: <20200619020602.118306-1-david@gibson.dropbear.id.au> References: <20200619020602.118306-1-david@gibson.dropbear.id.au> MIME-Version: 1.0 Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org The default behaviour for virtio devices is not to use the platforms normal DMA paths, but instead to use the fact that it's running in a hypervisor to directly access guest memory. That doesn't work if the guest's memory is protected from hypervisor access, such as with AMD's SEV or POWER's PEF. So, if a host trust limitation mechanism is enabled, then apply the iommu_platform=on option so it will go through normal DMA mechanisms. Those will presumably have some way of marking memory as shared with the hypervisor or hardware so that DMA will work. Signed-off-by: David Gibson --- hw/core/machine.c | 11 +++++++++++ 1 file changed, 11 insertions(+) diff --git a/hw/core/machine.c b/hw/core/machine.c index a71792bc16..8dfc1bb3f8 100644 --- a/hw/core/machine.c +++ b/hw/core/machine.c @@ -28,6 +28,8 @@ #include "hw/mem/nvdimm.h" #include "migration/vmstate.h" #include "exec/host-trust-limitation.h" +#include "hw/virtio/virtio.h" +#include "hw/virtio/virtio-pci.h" GlobalProperty hw_compat_5_0[] = { { "virtio-balloon-device", "page-poison", "false" }, @@ -1165,6 +1167,15 @@ void machine_run_board_init(MachineState *machine) * areas. */ machine_set_mem_merge(OBJECT(machine), false, &error_abort); + + /* + * Virtio devices can't count on directly accessing guest + * memory, so they need iommu_platform=on to use normal DMA + * mechanisms. That requires disabling legacy virtio support + * for virtio pci devices + */ + object_register_sugar_prop(TYPE_VIRTIO_PCI, "disable-legacy", "on"); + object_register_sugar_prop(TYPE_VIRTIO_DEVICE, "iommu_platform", "on"); } machine_class->init(machine);