Re: [Qemu-devel] [PATCH v4 09/16] apic: drop APICCommonState.idx and use APIC ID as index in local_apics[]

["Radim Krčmář" <rkrcmar@redhat.com>]

2016-07-14 18:54+0200, Igor Mammedov:
> local_apics[] is sized to contain all APIC ID supported in xAPIC mode,
> so use APIC ID as index in it instead of constantly increasing counter idx.
> 
> Fixes error "apic initialization failed" when a CPU hotplugged and
> unplugged more times than there are free slots in local_apics[].
> 
> Signed-off-by: Igor Mammedov <imammedo@redhat.com>
> ---

The new method handles dynamic APIC ID changes made by the guest and id
is set to the initial apic_id when realize is called, so it's even
better than the previous one as we have higher chance of hitting the
correct apic in local_apics[].

Reviewed-by: Radim Krčmář <rkrcmar@redhat.com>

> CC: Radim Krčmář <rkrcmar@redhat.com>
> CC: pbonzini@redhat.com
> ---
>  include/hw/i386/apic_internal.h |  1 -
>  hw/intc/apic.c                  | 16 +++++++---------
>  2 files changed, 7 insertions(+), 10 deletions(-)
> 
> diff --git a/include/hw/i386/apic_internal.h b/include/hw/i386/apic_internal.h
> index 67348e9..8330592 100644
> --- a/include/hw/i386/apic_internal.h
> +++ b/include/hw/i386/apic_internal.h
> @@ -174,7 +174,6 @@ struct APICCommonState {
>      uint32_t initial_count;
>      int64_t initial_count_load_time;
>      int64_t next_time;
> -    int idx; /* not actually common, used only by 'apic' derived class */
>      QEMUTimer *timer;
>      int64_t timer_expiry;
>      int sipi_vector;
> diff --git a/hw/intc/apic.c b/hw/intc/apic.c
> index b0d237b..f473572 100644
> --- a/hw/intc/apic.c
> +++ b/hw/intc/apic.c
> @@ -421,7 +421,7 @@ static int apic_find_dest(uint8_t dest)
>      int i;
>  
>      if (apic && apic->id == dest)
> -        return dest;  /* shortcut in case apic->id == apic->idx */
> +        return dest;  /* shortcut in case apic->id == local_apics[dest]->id */
>  
>      for (i = 0; i < MAX_APICS; i++) {
>          apic = local_apics[i];

(We could also update local_apics[] when APIC ID changes and drop the
 loop, but it's safer this way.)

> @@ -504,14 +504,14 @@ static void apic_deliver(DeviceState *dev, uint8_t dest, uint8_t dest_mode,
>          break;
>      case 1:
>          memset(deliver_bitmask, 0x00, sizeof(deliver_bitmask));
> -        apic_set_bit(deliver_bitmask, s->idx);
> +        apic_set_bit(deliver_bitmask, s->id);
>          break;
>      case 2:
>          memset(deliver_bitmask, 0xff, sizeof(deliver_bitmask));
>          break;
>      case 3:
>          memset(deliver_bitmask, 0xff, sizeof(deliver_bitmask));
> -        apic_reset_bit(deliver_bitmask, s->idx);
> +        apic_reset_bit(deliver_bitmask, s->id);
>          break;
>      }
>  
> @@ -871,20 +871,18 @@ static const MemoryRegionOps apic_io_ops = {
>  static void apic_realize(DeviceState *dev, Error **errp)
>  {
>      APICCommonState *s = APIC_COMMON(dev);
> -    static int apic_no;
>  
> -    if (apic_no >= MAX_APICS) {
> -        error_setg(errp, "%s initialization failed.",
> -                   object_get_typename(OBJECT(dev)));
> +    if (s->id >= MAX_APICS) {
> +        error_setg(errp, "%s initialization failed. APIC ID %d is invalid",
> +                   object_get_typename(OBJECT(dev)), s->id);
>          return;
>      }
> -    s->idx = apic_no++;
>  
>      memory_region_init_io(&s->io_memory, OBJECT(s), &apic_io_ops, s, "apic-msi",
>                            APIC_SPACE_SIZE);
>  
>      s->timer = timer_new_ns(QEMU_CLOCK_VIRTUAL, apic_timer, s);
> -    local_apics[s->idx] = s;
> +    local_apics[s->id] = s;
>  
>      msi_nonbroken = true;
>  }
> -- 
> 2.7.4
>