Yes, to support this the vfio driver would need to be able to exclude ranges of guest GPA space. Recent kernels already expose an IOVA list via the vfio API. Clearly, excluding GPA ranges has implications for hotplug. On x86 the ranges are pretty consistent, but IIRC differ between Intel and AMD. The vfio IOVA list was originally developed for an ARM use case though, and I imagine there's little or no consistency there.
Re: pci=nomsi, the reserved range exists regardless of whether MSI is actually used. -- 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
