My (limited) understanding of PCI was that the board and the PCI controller emulation define what the windows are where PCI BARs can live, and that PCI cards go there. (This certainly works for emulated PCI cards.) It's not clear to me why the host system imposes restrictions on the memory layout of the VM...
-- You received this bug notification because you are a member of qemu- devel-ml, which is subscribed to QEMU. https://bugs.launchpad.net/bugs/1869006 Title: PCIe cards passthrough to TCG guest works on 2GB of guest memory but fails on 4GB (vfio_dma_map invalid arg) Status in QEMU: New Bug description: During one meeting coworker asked "did someone tried to passthrough PCIe card to other arch guest?" and I decided to check it. Plugged SATA and USB3 controllers into spare slots on mainboard and started playing. On 1GB VM instance it worked (both cold- and hot- plugged). On 4GB one it did not: Błąd podczas uruchamiania domeny: internal error: process exited while connecting to monitor: 2020-03-25T13:43:39.107524Z qemu-system-aarch64: -device vfio-pci,host=0000:29:00.0,id=hostdev0,bus=pci.3,addr=0x0: VFIO_MAP_DMA: -22 2020-03-25T13:43:39.107560Z qemu-system-aarch64: -device vfio-pci,host=0000:29:00.0,id=hostdev0,bus=pci.3,addr=0x0: vfio 0000:29:00.0: failed to setup container for group 28: memory listener initialization failed: Region mach-virt.ram: vfio_dma_map(0x563169753c80, 0x40000000, 0x100000000, 0x7fb2a3e00000) = -22 (Invalid argument) Traceback (most recent call last): File "/usr/share/virt-manager/virtManager/asyncjob.py", line 75, in cb_wrapper callback(asyncjob, *args, **kwargs) File "/usr/share/virt-manager/virtManager/asyncjob.py", line 111, in tmpcb callback(*args, **kwargs) File "/usr/share/virt-manager/virtManager/object/libvirtobject.py", line 66, in newfn ret = fn(self, *args, **kwargs) File "/usr/share/virt-manager/virtManager/object/domain.py", line 1279, in startup self._backend.create() File "/usr/lib64/python3.8/site-packages/libvirt.py", line 1234, in create if ret == -1: raise libvirtError ('virDomainCreate() failed', dom=self) libvirt.libvirtError: internal error: process exited while connecting to monitor: 2020-03-25T13:43:39.107524Z qemu-system-aarch64: -device vfio-pci,host=0000:29:00.0,id=hostdev0,bus=pci.3,addr=0x0: VFIO_MAP_DMA: -22 2020-03-25T13:43:39.107560Z qemu-system-aarch64: -device vfio-pci,host=0000:29:00.0,id=hostdev0,bus=pci.3,addr=0x0: vfio 0000:29:00.0: failed to setup container for group 28: memory listener initialization failed: Region mach-virt.ram: vfio_dma_map(0x563169753c80, 0x40000000, 0x100000000, 0x7fb2a3e00000) = -22 (Invalid argument) I played with memory and 3054 MB is maximum value possible to boot VM with coldplugged host PCIe cards. To manage notifications about this bug go to: https://bugs.launchpad.net/qemu/+bug/1869006/+subscriptions
