On Sat, 21 Jan 2017 04:16:25 +0100 fassl <superfa...@gmail.com> 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