Re: [Qemu-devel] [PATCH] kvm: First step to push iothread lock out of inner run loop

[Avi Kivity]

On 06/24/2012 05:40 PM, Jan Kiszka wrote:
> On 2012-06-24 16:35, Avi Kivity wrote:
>> On 06/24/2012 05:08 PM, Jan Kiszka wrote:
>>> As a first step, I will post a series later that gets rid of
>>> kvm_flush_coalesced_mmio_buffer in the common vmexit path.
>> 
>> If you defer this, I can think of two places that need to flush:
>> - anything that accesses those memory areas (such as DMA to the
>> framebuffer, or updating the display)
> 
> - anything that accesses related areas (in case of VGA: PIO accesses to
> the control ports). I'm providing memory_region_set_flush_coalesced that
> allows to flush on non-coalesced region accesses as well. Some PIO
> accesses unfortunately still need open-coded
> qemu_flush_coalesced_mmio_buffer as they do not use memory regions yet.

Framebuffer access will bypass the MemoryRegionOps callbacks, did you
intend to hook those?

I'm not sure the problem is general enough to merit a check in our
generic mmio dispatch code (granted, now it has a check in the vcpu exit
path which is much worse).

-- 
error compiling committee.c: too many arguments to function