Re: [Qemu-devel] [PULL 2/5] apic: map APIC's MMIO region at each CPU's address space

[Paolo Bonzini <pbonzini@redhat.com>]

On 29/05/2015 20:04, Eduardo Habkost wrote:
>      static int apic_no;
> -    static bool mmio_registered;
> +    CPUState *cpu = CPU(s->cpu);
> +    MemoryRegion *root;
>  
>      if (apic_no >= MAX_APICS) {
>          error_setg(errp, "%s initialization failed.",
> @@ -307,11 +308,12 @@ static void apic_common_realize(DeviceState *dev, Error **errp)
>  
>      info = APIC_COMMON_GET_CLASS(s);
>      info->realize(dev, errp);
> -    if (!mmio_registered) {
> -        ICCBus *b = ICC_BUS(qdev_get_parent_bus(dev));
> -        memory_region_add_subregion(b->apic_address_space, 0, &s->io_memory);
> -        mmio_registered = true;
> -    }
> +
> +    root = address_space_root_memory_region(cpu->as);

I think just using cpu->as->root is okay.

> +    memory_region_add_subregion_overlap(root,
> +                                        s->apicbase & MSR_IA32_APICBASE_BASE,
> +                                        &s->io_memory,
> +                                        0x1000);

I think this patch is incorrect, because you do not install a separate
address space for each CPU.  Also, the CPU address space is only used
with TCG so it should be guarded by "if (tcg_enabled())".

Paolo

>      /* Note: We need at least 1M to map the VAPIC option ROM */
>      if (!vapic && s->vapic_control & VAPIC_ENABLE_MASK &&
> diff --git a/include/exec/memory.h b/include/exec/memory.h
> index b61c84f..a16650f 100644
> --- a/include/exec/memory.h
> +++ b/include/exec/memory.h
> @@ -1295,6 +1295,11 @@ void *address_space_map(AddressSpace *as, hwaddr addr,
>  void address_space_unmap(AddressSpace *as, void *buffer, hwaddr len,
>                           int is_write, hwaddr access_len);
>  
> +/* address_space_root_memory_region: get root memory region
> + *
> + * @as: #AddressSpace to be accessed
> + */
> +MemoryRegion *address_space_root_memory_region(AddressSpace *as);
>  
>  #endif
>  
> diff --git a/target-i386/cpu.c b/target-i386/cpu.c
> index 3305e09..f83e526 100644
> --- a/target-i386/cpu.c
> +++ b/target-i386/cpu.c
> @@ -2740,6 +2740,8 @@ static void x86_cpu_apic_create(X86CPU *cpu, Error **errp)
>      /* TODO: convert to link<> */
>      apic = APIC_COMMON(cpu->apic_state);
>      apic->cpu = cpu;
> +    cpu_set_apic_base(cpu->apic_state,
> +                      APIC_DEFAULT_ADDRESS | MSR_IA32_APICBASE_ENABLE);
>  }
>