Re: [RFC v2 19/24] target/arm: move aarch64_sync_32_to_64 (and vv) to cpu code

[Claudio Fontana]

On 3/2/21 7:23 AM, Richard Henderson wrote:
> On 3/1/21 8:49 AM, Claudio Fontana wrote:
>> and arm_phys_excp_target_el since it is tied up inside the
>> same #ifdef block.
>>
>> aarch64_sync_32_to_64 and aarch64_sync_64_to_32 are
>> mixed in with the tcg helpers, but they shouldn't, as they
>> are needed for kvm too, in the sysemu case.
> 
> Really?  Now that *is* surprising.  Again, please document.  Because I surely 
> cannot believe this to be used by kvm.
> 
> 
> r~
> 

Ok, will add comment here as well, they are needed by kvm64.c

There is lots that surprised me too on how kvm is bolted on top of tcg code 
currently;

partly related to this, if it can help understand this,

in kvm.c notice the kvm_arm_init_cpreg_list():

it basically undoes all TCG initializations in the cpreg_indexes, cpreg_values 
etc, and 
rebuilds the cpreg list based on the list read from the kernel.

Then, in kvm64.c:
kvm_arch_get_registers()
{
    ...
    if (!is_a64(env)) {
        aarch64_sync_64_to_32(env);
    }
    ...
    write_kvmstate_to_list(cpu);
    ...
    write_list_to_cpustate(cpu);
    ...
}

kvm_arch_put_registers()
{
    ...
    if (!is_a64(env)) {
        aarch64_sync_32_to_64(env);
    }
    ...
    write_cpustate_to_list(cpu, true);
    ...
    write_list_to_kvmstate(cpu, level)
    ...
}

Thanks,

Claudio