Re: [Xen-devel] Xen-unstable: pci-passthrough of device using MSI-X interrupts not working after commit x86/MSI: track host and guest masking separately

[linux@xxxxxxxxxxxxxx]

On 2015-06-26 17:22, Jan Beulich wrote:
> > > > On 26.06.15 at 17:04, <JBeulich@xxxxxxxx> wrote:
> > > > > On 26.06.15 at 15:38, <linux@xxxxxxxxxxxxxx> wrote:
> > > On 2015-06-26 14:41, Jan Beulich wrote:
> > > > > > > On 26.06.15 at 13:02, <linux@xxxxxxxxxxxxxx> wrote:
> > > > > Strange, i don't see *any* of your printk's being hit ... (xl dmesg
> > > > > attached).
> > > > So does the guest (in the working case) use MSI-X at all for the
> > > > device? I.e. it might be worth comparing the guest's 
> > > > /proc/interrupts
> > > > from both cases, as the lack of any of the debug messages clearly
> > > > suggests that such interrupts aren#t being set up.
> > > In the good case it uses one of them.
> > > (probably one per port and it has only one usb device connected at
> > > present)
> > >
> > > --
> > > Sander
> > >
> > >           CPU0       CPU1       CPU2       CPU3
> > >    0:         42          0          0          0   IO-APIC   2-edge
> > timer
> > > [...]
> > >   83:          8          0          0          0   xen-dyn-event     
> > > eth0-q3-rx
> > >   84:       2101          0          0          0  xen-pirq-msi-x    
> > > xhci_hcd
> > I think this explains it - you're running in PVHVM mode, which I
> > never tried with those patches. I'd even have to go dig to see how
> > they drive MSI-X in the first place in that case.
> I have an idea: In
>
> static unsigned int startup_msi_irq(struct irq_desc *desc)
> {
>     bool_t guest_masked = (desc->status & IRQ_GUEST) &&
>                           is_hvm_domain(desc->msi_desc->dev->domain);
>
>     if ( unlikely(!msi_set_mask_bit(desc, 0, guest_masked)) )
>         WARN();
>     return 0;
> }
>
> I think we need to also exclude the emuirq case (which is what I
> understand backs the pvhvm interrupt in the guest - Stefano,
> please confirm). For testing purposes, could you try simply passing
> zero instead of guest_masked here?
>
> Jan
I can confirm, with 0 it works !

--
Sander

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