Re: [Qemu-devel] [PATCH 1/1] xen-hvm.c: Add support for Xen access to vmport

[Alexander Graf <agraf@suse.de>]

On 29.09.14 14:21, Paolo Bonzini wrote:
> Il 29/09/2014 13:53, Alexander Graf ha scritto:
>>
>>   cpu_handle_ioreq()
>>   {
>>     ...
>>
>>     if (req->type == IOPORT_REGISTERS_SYNCHRONIZED) {
>>         cpu->xen_vcpu_dirty = true;
>>         synchronize_xen_to_env(xenptr, cpu);
>>     }
>>
>>     handle_ioreq();
>>
>>     if (req->type == IOPORT_REGISTERS_SYNCHRONIZED) {
>>         cpu->xen_vcpu_dirty = false;
>>         synchronize_env_to_xen(xenptr, cpu);
>>     }
>>
>>     ...
>>   }
>>
>>   void xen_cpu_synchronize_state(CPUState *cpu)
>>   {
>>     assert(cpu->xen_vcpu_dirty);
>>   }
>>
>> Then no changes to the vmport code would be necessary and this problems
>> where some code path wants to do direct access to registers
>> automatically tells us that things are broken.
> 
> Yeah, that would be possible.  You do not even need synchronize_state,
> it seems to me that it introduces more complication for little gain.

Well, it makes all accels behave the same and keep information always at
a single entity (the env struct). I don't think the vmport code should
have knowledge of a xen env struct.


Alex