Re: [PATCH 3/8] KVM: Handle device assignment to guests

Yang, Sheng
2008-07-17T02:27:53Z

On Thursday 17 July 2008 10:09:57 Han, Weidong wrote:
> Avi Kivity wrote:
> >> +static void kvm_pci_pt_work_fn(struct work_struct *work) +{
> >> + struct kvm_pci_pt_dev_list *match;
> >> + struct kvm_pci_pt_work *int_work;
> >> + int source;
> >> + unsigned long flags;
> >> + int guest_irq;
> >> + int host_irq;
> >> +
> >> + int_work = container_of(work, struct kvm_pci_pt_work, work); +
> >> + source = int_work->source ? KVM_PT_SOURCE_IRQ_ACK :
> >> KVM_PT_SOURCE_IRQ; + + /* This is taken to safely inject irq
>
> inside
>
> >> the guest. When + * the interrupt injection (or the ioapic
> >> code) uses a + * finer-grained lock, update this
> >> + */
> >> + mutex_lock(&int_work->kvm->lock);
> >> + read_lock_irqsave(&kvm_pci_pt_lock, flags);
> >> + match =
>
> kvm_find_pci_pt_dev(&int_work->kvm->arch.pci_pt_dev_head,
>
> >> NULL, + int_work->irq, source);
> >> + if (!match) {
> >> + printk(KERN_ERR "%s: no matching device assigned to
>
> guest "
>
> >> + "found for irq %d, source = %d!\n",
> >> + __func__, int_work->irq, int_work->source);
> >> + read_unlock_irqrestore(&kvm_pci_pt_lock, flags); +
>
> goto out;
>
> >> + }
> >> + guest_irq = match->pt_dev.guest.irq;
> >> + host_irq = match->pt_dev.host.irq;
> >> + read_unlock_irqrestore(&kvm_pci_pt_lock, flags);
> >> +
> >> + if (source == KVM_PT_SOURCE_IRQ)
> >> + kvm_set_irq(int_work->kvm, guest_irq, 1);
> >> + else {
> >> + kvm_set_irq(int_work->kvm, int_work->irq, 0);
> >> + enable_irq(host_irq);
> >> + }
> >> +out:
> >> + mutex_unlock(&int_work->kvm->lock);
> >> + kvm_put_kvm(int_work->kvm);
> >> +}
> >>
> >> +
> >> +/* FIXME: Implement the OR logic needed to make shared
> >> interrupts on + * this line behave properly + */
> >
> > Isn't this a showstopper? There is no easy way for a user to
> > avoid sharing, especially as we have only three pci irqs at
> > present.
>
> Currently it's not easy to avoid sharing. I think we can support
> MSI for assgined device to solve sharing problem.
>

I am working on the MSI support now.

--
regards
Yang, Sheng