From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:43462) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1cUrFQ-00047X-Kk for qemu-devel@nongnu.org; Sat, 21 Jan 2017 03:42:09 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1cUrFM-0001Zt-LU for qemu-devel@nongnu.org; Sat, 21 Jan 2017 03:42:08 -0500 Received: from mx1.redhat.com ([209.132.183.28]:45916) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1cUrFM-0001YT-FC for qemu-devel@nongnu.org; Sat, 21 Jan 2017 03:42:04 -0500 Date: Sat, 21 Jan 2017 01:41:59 -0700 From: Alex Williamson Message-ID: <20170121014159.064030ee@t450s.home> In-Reply-To: <1484968585.26205.2.camel@gmail.com> References: <1484968585.26205.2.camel@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] Nested PCI passthrough List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: fassl Cc: qemu-devel@nongnu.org On Sat, 21 Jan 2017 04:16:25 +0100 fassl wrote: > Hello, > > i am trying to pass through a graphic card to a guest within a guest. > So far i can see a text console within the target vm which says > "radeon: ring 0 test failed", so it times out in radeon_vce_ring_test > function. I am using qemu 2.8.50 at revision > 0f6bcf68a99efdc531b209551f2b760b0bdcc554. > > The relevant lowermost host arguments are: > -machine pc-q35-2.8,accel=kvm,kernel-irqchip=split > -device intel-iommu,intremap=on,eim=on > > If i dont set the x-vga flag for the passed through device in the > lowermost host the VM within the VM does not reset(?) the device during > shutdown and the screen freezes. If i do, the screen goes black and no > signal is going to the screen anymore and i can restart the target VM > without the whole machine freezing. (one has to set > CONFIG_VFIO_PCI_VGA=y in the kernel of the first VM, or call > pci_register_vga to get this) > > Also with irqchip=split the first vm cannot shutdown gracefully and > crashes during shutdown. > > I also can see some IRTE vector and trigger mode inconsistencies, can > they cause this? > > Or are there some quirks to be done to get this going? > > If anybody could lead me into the right direction or if there is work > going on in this field i would be more than glad to help testing. > > Thank you in advance This shouldn't even be possible right now, vfio-pci should generate an abort when used with intel-iommu. There is work in progress to make some form of vfio-pci work with intel-iommu, but devices that don't support function level reset (such as graphics cards) are going to have a more difficult time than most being supported in this configuration. What is your use case that you're even attempting this (or consider it a sane thing to do)? Thanks, Alex