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

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 

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.


Julien Grall



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