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[188.155.204.106]) by smtp.gmail.com with ESMTPSA id p1sm26490wmc.38.2019.11.25.09.53.17 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 25 Nov 2019 09:53:18 -0800 (PST) Date: Mon, 25 Nov 2019 18:53:16 +0100 From: Jean-Philippe Brucker To: "Michael S. Tsirkin" Subject: Re: [RFC 00/13] virtio-iommu on non-devicetree platforms Message-ID: <20191125175316.GC945122@lophozonia> References: <20191122105000.800410-1-jean-philippe@linaro.org> <20191122075438-mutt-send-email-mst@kernel.org> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20191122075438-mutt-send-email-mst@kernel.org> User-Agent: Mutt/1.12.2 (2019-09-21) Cc: virtio-dev@lists.oasis-open.org, kevin.tian@intel.com, gregkh@linuxfoundation.org, linux-pci@vger.kernel.org, sudeep.holla@arm.com, rjw@rjwysocki.net, virtualization@lists.linux-foundation.org, linux-acpi@vger.kernel.org, iommu@lists.linux-foundation.org, sebastien.boeuf@intel.com, jacob.jun.pan@intel.com, guohanjun@huawei.com, bhelgaas@google.com, jasowang@redhat.com, linux-arm-kernel@lists.infradead.org, lenb@kernel.org X-BeenThere: iommu@lists.linux-foundation.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: Development issues for Linux IOMMU support List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: iommu-bounces@lists.linux-foundation.org Sender: "iommu" 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 x86 > > [1]) > > 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. > > > > 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: > > > > - 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. > > > > - 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. > > A notifier seems easier for users. What are the disadvantages of > that? 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 _______________________________________________ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu