Re: [PATCH 11/11] xen/arm: Process pending vPCI map/unmap operations

[Julien Grall <julien@xxxxxxx>]

Hi Oleksandr,

On 06/09/2021 11:06, Oleksandr Andrushchenko wrote:
> On 06.09.21 12:53, Julien Grall wrote:
> > > > > > However, looking at the rest of the code, we already have a check for vpci in 
> > > > > > the common IOREQ code.
> > > > > Which may not be enabled as it depends on CONFIG_IOREQ_SERVER.
> > > > Right. My point is when CONFIG_IOREQ_SERVER is set then you would end up to 
> > > > call twice vpci_process_pending(). This will have an impact how on long your 
> > > > vCPU is going to running because you are doubling the work.
> > > So, you suggest that we have in the common IOREQ code something call like
> > >
> > > arch_vpci_process_pending? In case of x86 it will have the code currently found 
> > > in the
> > >
> > > common IOREQ sources and for Arm it will be nop?
> > No I am suggesting to move the call of the IOREQ code to hvm_do_resume() (on 
> > x86) and check_for_vcpu_work() (on Arm).
> Ok, I can move vPCI code to hvm_do_resume, but vPCI is only used for x86 PVH 
> Dom0.
AFAIK, Roger is planning to use it for x86 PVH guest.

> Do you still think hvm_do_resume is the right place?
I think so. AFAICT, on x86, the only caller of 
vcpu_ioreq_handle_completion() is hvm_do_resume(). So it makes sense to 
push one layer up.
Cheers,

--
Julien Grall