Re: [PATCH 1/2] i386/cpu: Enable SMM cpu addressspace

[Xiaoyao Li <xiaoyao.li@intel.com>]

On 7/30/2025 11:20 PM, Zhao Liu wrote:
>>>> +        cpu_address_space_init(cpu, 1, "cpu-smm", &smram_as_root);
>>>
>>> It is worth mentioning in the commit message that directly sharing
>>> MemoryRegion in CPUAddressSpace is safe.
>>
>> It's unnecessary to me. It's common that different Address space share the
>> same (root) memory region. e.g., for address space 0 for the cpu, though
>> what passed in is cpu->memory, they all point to system_memory.
> 
> For cpu->memory, there's the "object_ref(OBJECT(cpu->memory))" in
> cpu_exec_initfn().
> 
> But this case doesn't need to increase ref count like cpu->memory, since
> memory_region_ref() provides protection and it's enough.
> 
> This is the difference.
> 
> So it sounds like now it's more necessary to clarify this, no?
> 

clarify why smram_as_root doesn't need to be object_ref()'ed explicitly 
like what cpu_exec_initfn() does for cpu->memory?

As you saide,

cpu_address_space_init()
   -> address_space_init()
      -> memory_region_ref()

it already ensures the ref count is increased.

Why cpu_exec_initfn() increases the refcount of cpu->memory, is totally 
unrelated to cpu_address_space_init().