On Wed, 2020-06-17 at 17:17 -0400, Laine Stump wrote: > Until recently, an <interface type='network'> would automatically be > assigned model "rtl8139" (the default on x86 machinetypes), which in > turn would lead to the device being assigned a PCI address on a > conventional PCI controller (i.e. a pcie-to-pci-bridge). If the > network was a typical Linux host bridge-based network that used an > emulated device, this would be appropriate, since the guest actually > would get an emulated rtl8139 NIC, and that device is a conventional > PCI device. > > However, if the network being used was a pool of hostdev devices, the > guest would get an actual PCIe network device assigned from the host > via VFIO; while the interface model in that case is irrelevant for the > QEMU commandline to assign the device, the PCI address would have > already been assigned prior to runtime, so the address assignment > would be done based on the model='rtl8139' - a conventional PCI > device. VFIO assignment of a PCIe device to a conventional PCI slot > works, but we would rather have these devices in a PCIe slot. > > Since commit bdb8f2e4186, if <interface type='network'> points to a > etwork that is a pool of hostdev devices, the interface model will be > _unset_ by default. This patch uses that information when deciding > what type of slot to assign to the device: since all hostdev network > interfaces are SR-IOV VFs, and *all* SR-IOV network cards are PCIe, it > is safe to assume that the VFs are PCIe and we should assign then to a > PCIe slot in the guest. > > Signed-off-by: Laine Stump <laine@xxxxxxxxxx> Reviewed-by: Andrea Bolognani <abologna@xxxxxxxxxx> -- Andrea Bolognani / Red Hat / Virtualization
