[Qemu-devel] Re: [PATCH] APIC/IOAPIC EOI callback

[Alex Williamson <alex.williamson@redhat.com>]

On Fri, 2010-10-29 at 14:19 -0500, Anthony Liguori wrote:
> On 10/29/2010 12:56 PM, Alex Williamson wrote:
> > For device assignment, we need to know when the VM writes an end
> > of interrupt to the APIC, which allows us to re-enable interrupts
> > on the physical device.  Add a new wrapper for ioapic generated
> > interrupts with a callback on eoi and create an interface for
> > drivers to be notified on eoi.
> >
> > Signed-off-by: Alex Williamson<alex.williamson@redhat.com>
> > ---
> >
> > Note that the notifier and notifier_enabled eoi_client fields aren't
> > used here yet.  I'll send an RFC patch showing how we make use of
> > these with the proposed KVM_EOI_EVENTFD patches.
> >
> >   hw/apic.c   |   18 ++++++++++++++++--
> >   hw/apic.h   |    4 ++++
> >   hw/ioapic.c |   38 ++++++++++++++++++++++++++++++++++++--
> >   hw/pc.h     |   16 +++++++++++++++-
> >   4 files changed, 71 insertions(+), 5 deletions(-)
> >
> > diff --git a/hw/apic.c b/hw/apic.c
> > index 63d62c7..a24117b 100644
> > --- a/hw/apic.c
> > +++ b/hw/apic.c
> > @@ -22,6 +22,7 @@
> >   #include "host-utils.h"
> >   #include "sysbus.h"
> >   #include "trace.h"
> > +#include "pc.h"
> >
> >   /* APIC Local Vector Table */
> >   #define APIC_LVT_TIMER   0
> > @@ -103,6 +104,7 @@ struct APICState {
> >       int wait_for_sipi;
> >   };
> >
> > +static uint8_t vector_to_gsi_map[256] = { 0xff };
> >   static APICState *local_apics[MAX_APICS + 1];
> >   static int apic_irq_delivered;
> >
> > @@ -292,6 +294,15 @@ void apic_deliver_irq(uint8_t dest, uint8_t dest_mode,
> >                        trigger_mode);
> >   }
> >
> > +void apic_deliver_ioapic_irq(uint8_t dest, uint8_t dest_mode,
> > +                             uint8_t delivery_mode, uint8_t vector_num,
> > +                             uint8_t polarity, uint8_t trigger_mode, int gsi)
> > +{
> > +    vector_to_gsi_map[vector_num] = gsi;
> > +    apic_deliver_irq(dest, dest_mode, delivery_mode,
> > +                     vector_num, polarity, trigger_mode);
> > +}
> > +
> >   void cpu_set_apic_base(DeviceState *d, uint64_t val)
> >   {
> >       APICState *s = DO_UPCAST(APICState, busdev.qdev, d);
> > @@ -420,8 +431,11 @@ static void apic_eoi(APICState *s)
> >       if (isrv<  0)
> >           return;
> >       reset_bit(s->isr, isrv);
> > -    /* XXX: send the EOI packet to the APIC bus to allow the I/O APIC to
> > -            set the remote IRR bit for level triggered interrupts. */
> > +
> > +    if (vector_to_gsi_map[isrv] != 0xff) {
> > +        ioapic_eoi(vector_to_gsi_map[isrv]);
> > +        vector_to_gsi_map[isrv] = 0xff;
> > +    }
> >       apic_update_irq(s);
> >   }
> >
> > diff --git a/hw/apic.h b/hw/apic.h
> > index 8a0c9d0..59d0e37 100644
> > --- a/hw/apic.h
> > +++ b/hw/apic.h
> > @@ -8,6 +8,10 @@ void apic_deliver_irq(uint8_t dest, uint8_t dest_mode,
> >                                uint8_t delivery_mode,
> >                                uint8_t vector_num, uint8_t polarity,
> >                                uint8_t trigger_mode);
> > +void apic_deliver_ioapic_irq(uint8_t dest, uint8_t dest_mode,
> > +                             uint8_t delivery_mode,
> > +                             uint8_t vector_num, uint8_t polarity,
> > +                             uint8_t trigger_mode, int gsi);
> >   int apic_accept_pic_intr(DeviceState *s);
> >   void apic_deliver_pic_intr(DeviceState *s, int level);
> >   int apic_get_interrupt(DeviceState *s);
> > diff --git a/hw/ioapic.c b/hw/ioapic.c
> > index 5ae21e9..ffd1c92 100644
> > --- a/hw/ioapic.c
> > +++ b/hw/ioapic.c
> > @@ -26,6 +26,7 @@
> >   #include "qemu-timer.h"
> >   #include "host-utils.h"
> >   #include "sysbus.h"
> > +#include "qlist.h"
> >
> >   //#define DEBUG_IOAPIC
> >
> > @@ -61,6 +62,39 @@ struct IOAPICState {
> >       uint64_t ioredtbl[IOAPIC_NUM_PINS];
> >   };
> >
> > +static QLIST_HEAD(ioapic_eoi_client_list,
> > +                  ioapic_eoi_client) ioapic_eoi_client_list =
> > +                  QLIST_HEAD_INITIALIZER(ioapic_eoi_client_list);
> > +
> > +int ioapic_register_eoi_client(ioapic_eoi_client *client)
> > +{
> > +    QLIST_INSERT_HEAD(&ioapic_eoi_client_list, client, list);
> > +    return 0;
> > +}
> > +
> > +void ioapic_unregister_eoi_client(ioapic_eoi_client *client)
> > +{
> > +    QLIST_REMOVE(client, list);
> > +}
> > +
> > +int ioapic_eoi_client_get_fd(ioapic_eoi_client *client)
> > +{
> > +    if (!client->notifier_enabled) {
> > +        return -ENODEV;
> > +    }
> > +    return event_notifier_get_fd(&client->notifier);
> > +}
> > +
> > +void ioapic_eoi(int gsi)
> > +{
> > +    ioapic_eoi_client *client;
> > +    QLIST_FOREACH(client,&ioapic_eoi_client_list, list) {
> > +        if (client->irq == gsi) {
> > +            client->eoi(client);
> > +        }
> > +    }
> > +}
> >    
> 
> I think this all goes away with a NotifierList.

Are you thinking of an array of 256 NotifierLists, one per irq?  I'm not
sure how else I could keep track of which Notifier is associated with
which irq.  That seems a little excessive unless we start getting a lot
more users of this callback.  Thanks,

Alex