https://bugzilla.kernel.org/show_bug.cgi?id=82761 --- Comment #8 from Ansa89 <ansalonistefano@xxxxxxxxx> --- (In reply to Alex Williamson from comment #6) > Are these 3 separate NICs plugged into PCI slots on the motherboard or is > this a single triple-port card with embedded PCIe-to-PCI bridge? They are 3 separate NICs plugged into 3 separate PCI slots. > You might be able to run the IOMMU in passthrough mode with iommu=pt > r8169.use_dac=1, but note the warning in modinfo "use_dac:Enable PCI DAC. > Unsafe on 32 bit PCI slot." Unfortunately if you don't enable use_dac, then > intel_iommu will ignore the passthrough option for these devices. I tried using "intel_iommu=pt", but it didn't work (resulted in vt-d disabled). However with "intel_iommu=on iommu=pt" the errors remain (probably because I didn't add "r8169.use_dac=1"). I'm on a 64 bit system, but I think it has nothing to with "32 bit PCI slot". > Also note that this problem has nothing to do with Virtualization/KVM. > Drivers/Network or perhaps Drivers/PCI would be a more appropriate > classification. I searched for "IOMMU" section but it doesn't exist. I will probably change classification to "Drivers/PCI". (In reply to Alex Williamson from comment #7) > I'm guessing this might be the motherboard here: MSI ZH77A-G43 Yes, that is my motherboard. > Since you're apparently trying to use VT-d on this system for KVM and > therefore presumably device assignment, I'll note that you will never be > able to successfully assign the conventional PCI devices separately between > guests or between host and guests. The IOMMU does not have the granularity > to create separate IOMMU domains per PCI slot in this topology. Also, some > (all?) Realtek NICs have some strange backdoors to PCI configuration space > that make them poor targets for PCI device assignment: Yes, I'm trying to do device assignment, but not with those NICs: I want to pass only the nVidia PCIe VGA card to guest; while all NICs (and the integrated VGA card) will remain available to host. It would be nice if there would be a way to prevent IOMMU on these NICs (or something like that). SIDE NOTE: in the qemu commit they talk about RTL8168, but I have real RTL8169 devices (the only RTL8168 device is the integrated NIC and for that device I'm using r8168 driver from realtek compiled by hand). -- You are receiving this mail because: You are watching the assignee of the bug. -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
