From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: virtio-dev-return-6404-cohuck=redhat.com@lists.oasis-open.org Sender: List-Post: List-Help: List-Unsubscribe: List-Subscribe: Received: from lists.oasis-open.org (oasis-open.org [10.110.1.242]) by lists.oasis-open.org (Postfix) with ESMTP id 580AF985DB8 for ; Mon, 25 Nov 2019 17:53:20 +0000 (UTC) Date: Mon, 25 Nov 2019 18:53:16 +0100 From: Jean-Philippe Brucker Message-ID: <20191125175316.GC945122@lophozonia> References: <20191122105000.800410-1-jean-philippe@linaro.org> <20191122075438-mutt-send-email-mst@kernel.org> MIME-Version: 1.0 In-Reply-To: <20191122075438-mutt-send-email-mst@kernel.org> Subject: [virtio-dev] Re: [RFC 00/13] virtio-iommu on non-devicetree platforms Content-Type: text/plain; charset=WINDOWS-1252 Content-Transfer-Encoding: quoted-printable Content-Disposition: inline To: "Michael S. Tsirkin" Cc: linux-acpi@vger.kernel.org, linux-arm-kernel@lists.infradead.org, iommu@lists.linux-foundation.org, virtualization@lists.linux-foundation.org, linux-pci@vger.kernel.org, virtio-dev@lists.oasis-open.org, rjw@rjwysocki.net, lenb@kernel.org, lorenzo.pieralisi@arm.com, guohanjun@huawei.com, sudeep.holla@arm.com, gregkh@linuxfoundation.org, joro@8bytes.org, bhelgaas@google.com, jasowang@redhat.com, jacob.jun.pan@intel.com, eric.auger@redhat.com, sebastien.boeuf@intel.com, kevin.tian@intel.com List-ID: On Fri, Nov 22, 2019 at 08:00:46AM -0500, Michael S. Tsirkin wrote: > > (2) In addition, there are some concerns about having virtio depend on > > ACPI or DT. Some hypervisors (Firecracker, QEMU microvm, kvmtool x8= 6 > > [1]) >=20 > power? In kvmtool it boot with device tree. It also doesn't need virtio-iommu I think, since it has its own paravirtualized interface. > > don't currently implement those methods. > >=20 > > It was suggested to embed the topology description into the device. > > It can work, as demonstrated at the end of this RFC, with the > > following limitations: > >=20 > > - The topology description must be read before any endpoint managed > > by the IOMMU is probed, and even before the virtio module is > > loaded. This RFC uses a PCI quirk to manually parse the virtio > > configuration. It assumes that all endpoints managed by the IOMMU > > are under this same PCI host. > >=20 > > - I don't have a solution for the virtio-mmio transport at the > > moment, because I haven't had time to modify a host to test it. I > > think it could either use a notifier on the platform bus, or > > better, a new 'iommu' command-line argument to the virtio-mmio > > driver. >=20 > =09A notifier seems easier for users. What are the disadvantages of > =09that? For each device we have to check if it's virtio-mmio, then map the MMIO resource and check the device type. Having a dedicated command-line argument would be more efficient. Thanks, Jean --------------------------------------------------------------------- To unsubscribe, e-mail: virtio-dev-unsubscribe@lists.oasis-open.org For additional commands, e-mail: virtio-dev-help@lists.oasis-open.org