On , Jul 22, 2020 at 02:44:14PM +0200, Alan wrote:
> On Wed, Jul 22, 2020 at 02:44:14PM +0200, Greg KH wrote:
> > On Wed, Jul 22, 2020 at 07:57:48PM +0800, WeitaoWangoc wrote:
> > > This bug is found in Zhaoxin platform, but it's a commom code bug.
> > > Fail sequence:
> > > step1: Unbind UHCI controller from native driver;
> > > step2: Bind UHCI controller to vfio-pci, which will put UHCI controller
> > > in one
> vfio
> > >group's device list and set UHCI's dev->driver_data to struct
> vfio-pci(for UHCI)
> >
> > Hah, that works? How do you do that properly? What code does that?
>
> Yeah, that can't possibly work. The USB core expects that any host
> controller device (or at least, any PCI host controller device) has its
> driver_data set to point to a struct usb_hcd. It doesn't expect a host
> controller to be bound to anything other than a host controller driver.
>
> Things could easily go very wrong here. For example, suppose at this
> point the ehci-hcd driver just happens to bind to the EHCI controller.
> When this happens, the EHCI controller hardware takes over all the USB
> connections that were routed to the UHCI controller. How will vfio-pci
> deal with that? Pretty ungracefully, I imagine.
>
> The only way to make this work at all is to unbind both uhci-hcd and
> ehci-hcd first. Then after both are finished you can safely bind
> vfio-pci to the EHCI controller and the UHCI controllers (in that
> order).
>
I'm agree with you, unbind both uhci-hcd and ehci-hcd first then bind to
vfio-pci is a more reasonable sequence. Our experiments prove that this
sequence is indeed good as expected.
However, I did not find a formal document to prescribe this order.
Unfortunately, some application software such as virt-manager/qemu assign
UHCI/EHCI to guest OS has the same bind/unbind sequence as test “by hand”.
Do we need to consider compatibility with this application scenario?
The following log is captured when starting then shutdown the
virtual machine.
/* starting virtual machine*/
[ 2785.250001] audit: type=1400 audit(1594375837.191:48): apparmor="STATUS"
operation="profile_load" profile="unconfined"
name="libvirt-fa674e73-67a2-4672-8524-e62dea8a3c6c" pid=2008
comm="apparmor_parser"
[ 2785.467510] uhci_hcd :00:10.0: remove, state 4
[ 2785.472426] usb usb1: USB disconnect, device number 1
/*bind :00:10.0 to vfio-pci*/
[ 2785.478798] uhci_hcd :00:10.0: USB bus 1 deregistered
[ 2785.568741] uhci_hcd :00:10.1: remove, state 1
[ 2785.573562] usb usb2: USB disconnect, device number 1
[ 2785.578793] usb 2-2: USB disconnect, device number 3
[ 2785.758016] uhci_hcd :00:10.1: USB bus 2 deregistered
/*bind :00:10.1 to vfio-pci*/
[ 2786.037448] ehci-pci :00:10.7: remove, state 4
[ 2786.042460] usb usb3: USB disconnect, device number 1
[ 2786.048700] ehci-pci :00:10.7: USB bus 3 deregistered
/*bind :00:10.7 to vfio-pci*/
[ 2787.518041] audit: type=1400 audit(1594375839.459:49): apparmor="STATUS"
operation="profile_replace" profile="unconfined"
name="libvirt-fa674e73-67a2-4672-8524-e62dea8a3c6c" pid=2034
comm="apparmor_parser"
[ 2788.290706] audit: type=1400 audit(1594375840.231:50): apparmor="STATUS"
operation="profile_replace" profile="unconfined"
name="libvirt-fa674e73-67a2-4672-8524-e62dea8a3c6c" pid=2037
comm="apparmor_parser"
[ 2788.960070] audit: type=1400 audit(1594375840.899:51): apparmor="STATUS"
operation="profile_replace" info="same as current profile, skipping"
profile="unconfined" name="libvirt-fa674e73-67a2-4672-8524-e62dea8a3c6c"
pid=2040 comm="apparmor_parser"
[ 2788.968821] virbr0: port 2(vnet0) entered blocking state
[ 2788.988159] virbr0: port 2(vnet0) entered disabled state
[ 2788.993711] device vnet0 entered promiscuous mode
[ 2788.999453] virbr0: port 2(vnet0) entered blocking state
[ 2789.005053] virbr0: port 2(vnet0) entered listening state
[ 2789.098717] systemd-journald[286]: Successfully sent stream file descriptor
to service manager.
[ 2789.564241] audit: type=1400 audit(1594375841.507:52): apparmor="STATUS"
operation="profile_replace" profile="unconfined"
name="libvirt-fa674e73-67a2-4672-8524-e62dea8a3c6c" pid=2065
comm="apparmor_parser"
[ 2791.028028] virbr0: port 2(vnet0) entered learning state
[ 2793.047999] virbr0: port 2(vnet0) entered forwarding state
[ 2793.053449] virbr0: topology change detected, propagating
[ 2793.433604] vfio_cap_init: :00:10.7 hiding cap 0xa
/* shutdown virtual machine*/
[ 3838.772058] systemd-journald[286]: Successfully sent stream file descriptor
to service manager.
[ 3838.815819] systemd-journald[286]: Successfully sent stream file descriptor
to service manager.
[ 3838.871002] systemd-journald[286]: Successfully sent stream file descriptor
to service manager.
[ 3838.884606] systemd-journald[286]: Successfully sent stream file descriptor
to service manager.
[ 3838.894514] systemd-journald[286]: Successfully sent stream file descriptor
to service manager.
[ 3838.896791] rfkill:
