On Wed, Jun 13, 2012 at 04:01:24PM +0300, Gleb Natapov wrote:
> On Mon, Jun 11, 2012 at 02:19:22PM +0300, Michael S. Tsirkin wrote:
> > We do not want a potential broadcast to all VCPUs to run in
> > a host IRQ handler. Implement an API that sends an MSI
> > interrupt but only if it's safe from interrupt context,
> > that is if it is a unicast.
> >
> We will still iterate over all vcpus, we may as well deliver to them. Or
> you want to avoid a lot of vcpu kicks?
This is an intermediate stage (thus RFC) for adding a cache:
we can't cache if it's a broadcast.
> > Signed-off-by: Michael S. Tsirkin <mst@xxxxxxxxxx>
> > ---
> > include/linux/kvm_host.h | 2 ++
> > virt/kvm/irq_comm.c | 37 ++++++++++++++++++++++++++++++++-----
> > 2 files changed, 34 insertions(+), 5 deletions(-)
> >
> > diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
> > index c446435..ddb476a 100644
> > --- a/include/linux/kvm_host.h
> > +++ b/include/linux/kvm_host.h
> > @@ -618,6 +618,8 @@ void kvm_get_intr_delivery_bitmask(struct kvm_ioapic *ioapic,
> > int kvm_set_irq(struct kvm *kvm, int irq_source_id, u32 irq, int level);
> > int kvm_set_msi(struct kvm_kernel_irq_routing_entry *irq_entry, struct kvm *kvm,
> > int irq_source_id, int level);
> > +int kvm_set_msi_inatomic(struct kvm_kernel_irq_routing_entry *irq_entry,
> > + struct kvm *kvm);
> > void kvm_notify_acked_irq(struct kvm *kvm, unsigned irqchip, unsigned pin);
> > void kvm_register_irq_ack_notifier(struct kvm *kvm,
> > struct kvm_irq_ack_notifier *kian);
> > diff --git a/virt/kvm/irq_comm.c b/virt/kvm/irq_comm.c
> > index 5afb431..3395e03 100644
> > --- a/virt/kvm/irq_comm.c
> > +++ b/virt/kvm/irq_comm.c
> > @@ -114,13 +114,20 @@ int kvm_irq_delivery_to_apic(struct kvm *kvm, struct kvm_lapic *src,
> > return r;
> > }
> >
> > -int kvm_set_msi(struct kvm_kernel_irq_routing_entry *e,
> > - struct kvm *kvm, int irq_source_id, int level)
> > +static bool kvm_msi_is_multicast(unsigned dest, int dest_mode)
> > {
> > - struct kvm_lapic_irq irq;
> > + if (dest_mode == 0)
> > + /* Physical mode. */
> > + return dest == 0xff;
> > + else
> > + /* Logical mode. */
> > + return dest & (dest - 1);
> > +}
> >
> > - if (!level)
> > - return -1;
> > +static int __kvm_set_msi(struct kvm_kernel_irq_routing_entry *e,
> > + struct kvm *kvm, bool noblock)
> > +{
> > + struct kvm_lapic_irq irq;
> >
> > trace_kvm_msi_set_irq(e->msi.address_lo, e->msi.data);
> >
> > @@ -134,10 +141,30 @@ int kvm_set_msi(struct kvm_kernel_irq_routing_entry *e,
> > irq.level = 1;
> > irq.shorthand = 0;
> >
> > + /* Multicast MSI doesn't really block but might take a long time. */
> > + if (unlikely(noblock && kvm_msi_is_multicast(irq.dest_id,
> > + irq.delivery_mode)))
> delivery_mode? Should be dest_mode. But you probably need to check that
> delivery_mode is not ExtINT either.
>
> > + return -EWOULDBLOCK;
> > +
> > /* TODO Deal with RH bit of MSI message address */
> > return kvm_irq_delivery_to_apic(kvm, NULL, &irq);
> > }
> >
> > +int kvm_set_msi_inatomic(struct kvm_kernel_irq_routing_entry *e,
> > + struct kvm *kvm)
> > +{
> > + return __kvm_set_msi(e, kvm, true);
> > +}
> > +
> > +int kvm_set_msi(struct kvm_kernel_irq_routing_entry *e,
> > + struct kvm *kvm, int irq_source_id, int level)
> > +{
> > + if (unlikely(!level))
> > + return -1;
> > +
> > + return __kvm_set_msi(e, kvm, false);
> > +}
> > +
> > int kvm_send_userspace_msi(struct kvm *kvm, struct kvm_msi *msi)
> > {
> > struct kvm_kernel_irq_routing_entry route;
> > --
> > MST
> >
> > --
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>
> --
> Gleb.
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