Hi all, Thanks for the reply Bjorn! Got a Mail Delivery system message back on this e-mail because it contained HTML. Gawd dammit gmail! Sorry to all of you that are getting this 2 times. Also; Alex' comment got in between here. So I'll answer that one here too (at the bottom). Yes, you understand correctly. The issue here is that I have a PCI XHCI controller that I want to bind to the vfio-pci instead of the xhci_hcd. The reason is that I want to be able to pass through this device to a virtual machine. I'm not sure if I understand your question 'Have you added "0x1b73 0x1100" to vfio-pci/new_id previously', but I'll try to answer; no, I don't add it during the 5.11 (and newer kernels) boot process or anything like that, I only add it manually like the commands in the bugzilla bug report when starting the virtual machine. And I also do it only once. If someone is interested in the source on why I'm doing it like this, check out https://www.heiko-sieger.info/running-windows-10-on-linux-using-kvm-with-vga-passthrough/#Part_14_-_Passing_more_PCI_devices_to_guest Unfortunately the workaround don't seem to be working: [root@silje ~]# echo '0000:06:00.0' > /sys/bus/pci/drivers/virtio-pci/bind -bash: echo: write error: No such device Alex; Yes, the patch works as expected for (errorusly) double adding to new_id, the problem here is that this is the first time echoing to new_id. -Idar On Fri, Aug 13, 2021 at 7:32 PM Alex Williamson <alex.williamson@xxxxxxxxxx> wrote: > > On Fri, 13 Aug 2021 11:53:07 -0500 > Bjorn Helgaas <helgaas@xxxxxxxxxx> wrote: > > > [+cc Alex, kvm, linux-pci] > > > > On Fri, Aug 13, 2021 at 09:43:39AM +0200, Idar Lund wrote: > > > Hi, > > > > > > I've been struggling with an error in linux since 5.11. Please find my bug > > > report here: > > > https://bugzilla.redhat.com/show_bug.cgi?id=1945565 > > > > > > Then I stumbled upon this mail thread: > > > https://www.spinics.net/lists/linux-pci/msg102243.html which seems related. > > > > > > Is there another way to do this in 5.11+ or is this an unintentionally bug > > > that got introduced in 5.11? > > > > Hi Idar, sorry for the trouble and thanks for the report! I cc'd some > > VFIO experts who know more than I do about this. > > > > If I understand correctly, you have a PCI XHCI controller: > > > > pci 0000:06:00.0: [1b73:1100] type 00 class 0x0c0330 > > xhci_hcd 0000:06:00.0: xHCI Host Controller > > > > and you want to unbind the xhci_hcd driver and bind vfio-pci instead: > > > > # echo '0000:06:00.0' > /sys/bus/pci/devices/0000\:06\:00.0/driver/unbind > > # echo 0x1b73 0x1100 > /sys/bus/pci/drivers/vfio-pci/new_id > > > > In v5.10 (5.10.17-200.fc33.x86_64) this worked fine, but in v5.11 > > (5.11.9-200.fc33.x86_64) the "new_id" write returns -EEXIST and > > binding to vfio-pci fails. > > > > The patch you pointed out appeared in v5.11 as 3853f9123c18 ("PCI: > > Avoid duplicate IDs in driver dynamic IDs list") [1], and I agree it > > looks suspicious. There haven't been any significant changes to > > pci-driver.c since then. > > > > Have you added "0x1b73 0x1100" to vfio-pci/new_id previously? I think > > in v5.10, that would silently work (possibly adding duplicate entries > > to the dynamic ID list) and every write to vfio-pci/new_id would make > > vfio-pci try to bind to the device. > > > > In v5.11, if you write a duplicate ID to vfio-pci/new_id, you would > > get -EEXIST and no attempt to bind. As far as I know, the dynamic ID > > list is not visible in sysfs, so it might be hard to avoid writing a > > duplicate. > > > > But if the vfio-pci dynamic ID list already contains "0x1b73 0x1100", > > you should be able to ask vfio-pci to bind to the device like this: > > > > # echo 0000:06:00.0 > /sys/bus/pci/drivers/virtio-pci/bind > > > > I don't know if that's a solution, but would be useful to know whether > > it's a workaround. > > [root@x1 vfio-pci]# echo 0x1b73 0x1100 > new_id > [root@x1 vfio-pci]# echo 0x1b73 0x1100 > new_id > bash: echo: write error: File exists > [root@x1 vfio-pci]# uname -r > 5.12.15-200.fc33.x86_64 > > Seems like it behaves as expected now. The new_id interface has some > inherit issues, essentially all vfio-pci dynamic binding cases should > instead be using the driver_override interface. The driverctl utility > already makes use of this and will make your life a tiny bit easier. > Thanks, > > Alex >
