[vfio-users] Trying to pass through USB controller.

[Andrew A.]

Thanks for taking the time!

On Wed, Sep 6, 2017 at 11:38 Samuel Holland <samuel at sholland.org> wrote:

> Hello,
>
> On 08/31/17 22:45, Andrew A. wrote:
> > I tried the following to no avail:
> > setpci -s 00:14.0 0xd4.L=0x00000000
> > setpci -s 00:14.0 0xdc.L=0x00000000
> >
> > This seems not to have taken hold upon readback:
> > setpci -s 00:14.0 0xd4.L
> > 00003fff
> > setpci -s 00:14.0 0xdc.L
> > 0000003f
>
> This is also what I get on my machine.
>
> > (And indeed, the same problem persists -- qemu changes the port
> > mappings as soon as I boot a guest, locking me out of my host machine
> > until I ssh in and run 'setpci .. d0' again)
> >
> > I took a look at what I believe is the R/WL property for these
> > settings, which is bit 31 of D20:F0:40h according to the datasheet,
> > so:
> > setpci -s 00:14.0 0x40.L
> > 803609fd
> > sudo setpci -s 00:14.0 0x40.L=0x003609fd
>
> Note that the ACCTRL bit is not documented in that register, further
> suggesting that it is a BIOS-only control bit. Likely it is a write-once
> bit, so once it has been set, it cannot be unset.
>
> > But this again didn't seem to have an effect:
> > setpci -s 00:14.0 0x40.L
> > 803609fd
>
> Note that other bits in the register can be changed (e.g. you can change
> the 6 to a 0 to turn off power management, and change it back to a 6).
> Just the top bit is write-protected.
>
> >> Another potential problem is that your BIOS on the host may
> >> write-protect the mask register. In that case, see the datasheet
> >> for how to unlock it, if possible.
> >
> > Right, and despite trying to remove the write protect I'm inclined
> > to think my unlocking commands are not working for some reason. Do
> > you see anything wrong with what I've tried here?
>
> No, other than that it doesn't work :) I guess we're just out of luck
> then, without doing something like patching your BIOS (so the bit never
> gets set).
>
> > Thanks.
>
> Regards,
> Samuel
>
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