From patchwork Thu May 21 03:43:04 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: David Gibson X-Patchwork-Id: 11562175 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 4F6F290 for ; Thu, 21 May 2020 03:43:29 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 2F9272078B for ; Thu, 21 May 2020 03:43:29 +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="hKD3NL+M" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728265AbgEUDn2 (ORCPT ); Wed, 20 May 2020 23:43:28 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:39194 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728267AbgEUDnV (ORCPT ); Wed, 20 May 2020 23:43:21 -0400 Received: from ozlabs.org (ozlabs.org [IPv6:2401:3900:2:1::2]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id B2880C061A0E for ; Wed, 20 May 2020 20:43:21 -0700 (PDT) Received: by ozlabs.org (Postfix, from userid 1007) id 49SFnt6QqDz9sVG; Thu, 21 May 2020 13:43:14 +1000 (AEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=gibson.dropbear.id.au; s=201602; t=1590032594; bh=FeXJqAbqicMbULwoyafKv73wne8M05KzRx96/hIBYS8=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=hKD3NL+MimoyWtFhDKs3K9p+VZwC6KMyzmpIeq1qoV1LFv5JdiDY1wejmyv0RUKjk ONF9bpuW5w2G8jCr8Hb7sCO79YxbenlKa4w6Cfmz8+F2wEdgzdDCl7Dh1Ft2cdt6z9 mNxWLF8UT0kuEbn9hhCJ+pZsYJMSpsqAJM855Xjs= From: David Gibson To: qemu-devel@nongnu.org, brijesh.singh@amd.com, frankja@linux.ibm.com, dgilbert@redhat.com, pair@us.ibm.com Cc: qemu-ppc@nongnu.org, kvm@vger.kernel.org, David Gibson , mdroth@linux.vnet.ibm.com, cohuck@redhat.com, Marcel Apfelbaum , Paolo Bonzini , "Michael S. Tsirkin" , Richard Henderson , Eduardo Habkost Subject: [RFC v2 18/18] guest memory protection: Alter virtio default properties for protected guests Date: Thu, 21 May 2020 13:43:04 +1000 Message-Id: <20200521034304.340040-19-david@gibson.dropbear.id.au> X-Mailer: git-send-email 2.26.2 In-Reply-To: <20200521034304.340040-1-david@gibson.dropbear.id.au> References: <20200521034304.340040-1-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 guest memory protection 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 88d699bceb..cb6580954e 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/guest-memory-protection.h" +#include "hw/virtio/virtio.h" +#include "hw/virtio/virtio-pci.h" GlobalProperty hw_compat_5_0[] = {}; const size_t hw_compat_5_0_len = G_N_ELEMENTS(hw_compat_5_0); @@ -1159,6 +1161,15 @@ 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);