Re: [Qemu-devel] [RFC qom-cpu v2 1/8] apic: remove apic_no from apic_init_common()

[chenfan <chen.fan.fnst@cn.fujitsu.com>]

On Tue, 2013-09-10 at 14:16 +0200, Andreas Färber wrote:
> Am 10.09.2013 14:09, schrieb Igor Mammedov:
> > On Tue, 10 Sep 2013 17:43:41 +0800
> > Chen Fan <chen.fan.fnst@cn.fujitsu.com> wrote:
> > 
> >> the 'apic_no' is increased by one when initialize/create a vCPU each time,
> >> which causes APICCommonState s->idx always is increased.
> >> but if we want to re-add a vCPU after removing a vCPU, we need to re-use the
> >> vacant s->idx which the corresponding vCPU had been removed. 
> >> so we could use the unique cpu apic_id instead of the progressive s->idx.
> >>
> >> Signed-off-by: Chen Fan <chen.fan.fnst@cn.fujitsu.com>
> >> ---
> >>  hw/intc/apic_common.c | 4 +---
> >>  target-i386/cpu.c     | 1 +
> >>  2 files changed, 2 insertions(+), 3 deletions(-)
> >>
> >> diff --git a/hw/intc/apic_common.c b/hw/intc/apic_common.c
> >> index a0beb10..5568621 100644
> >> --- a/hw/intc/apic_common.c
> >> +++ b/hw/intc/apic_common.c
> >> @@ -289,13 +289,11 @@ static int apic_init_common(ICCDevice *dev)
> >>      APICCommonState *s = APIC_COMMON(dev);
> >>      APICCommonClass *info;
> >>      static DeviceState *vapic;
> >> -    static int apic_no;
> >>      static bool mmio_registered;
> >>  
> >> -    if (apic_no >= MAX_APICS) {
> >> +    if (s->idx >= MAX_APICS) {
> >>          return -1;
> >>      }
> >> -    s->idx = apic_no++;
> >>  
> >>      info = APIC_COMMON_GET_CLASS(s);
> >>      info->init(s);
> >> diff --git a/target-i386/cpu.c b/target-i386/cpu.c
> >> index 42c5de0..2b99683 100644
> >> --- a/target-i386/cpu.c
> >> +++ b/target-i386/cpu.c
> >> @@ -2322,6 +2322,7 @@ static void x86_cpu_apic_create(X86CPU *cpu, Error **errp)
> >>      /* TODO: convert to link<> */
> >>      apic = APIC_COMMON(env->apic_state);
> >>      apic->cpu = cpu;
> >> +    apic->idx = env->cpuid_apic_id;
> > earlier here we set:
> >  qdev_prop_set_uint8(env->apic_state, "id", env->cpuid_apic_id);
> > so apic->idx = env->cpuid_apic_id is redundant.
> > 
> > it would be better to search by apic->id and preferably replace O(MAX_APIC) scans with
> > a faster approach since for TCG iqr delivery might be a hot path, dropping MAX_APIC
> > altogether and using dynamic present APICs list.
> 
> Independent of that, the recent removal of X86_CPU() cast from
> x86_env_get_cpu() should allow us to finally tackle the TODO above,
> moving apic_state field from CPUX86State to X86CPU.
> 
I will send V3 patches later including modification pointed out above. 

Thanks

> Andreas
> 
> > 
> >>  }
> >>  
> >>  static void x86_cpu_apic_realize(X86CPU *cpu, Error **errp)
> > 
> 
>