Re: [Xen-devel] [PATCH 00/25 v6] SBSA UART emulation support in Xen

[Julien Grall <julien.grall@xxxxxxx>]

On 20/07/17 10:40, Bhupinder Thakur wrote:
> Hi Julien,
Hi Bhupinder,

> The issue seems to be that domain_vpl011_deinit() is not getting
> called when we destroy the domain. On further debugging, i found that
> domain_relinquish_resources was failing in domain_kill() function.
>
> I believe that issue could be that arch_domain_destroy() (from where
> domain_vpl011_deinit() is called) is called later and because
> domain_kill() fails, it is not getting called. Once I moved the
> domain_vpl011_deinit() inside domain_kill(), the domain is getting
> cleaned up properly.
What do you mean by domain_kill fails? The function may take time to 
execute so it may return -ERESTART for preemption and be restarted later on.
The problem here is until domain_vpl011_deinit is called, there is still 
a reference taken on the guest memory and therefore on the domain. So 
the domain will not get fully destroyed (domain_destroy is called when 
the last reference on the domain is dropped).
Because domain_vpl011_deinit is called from domain_destroy, there will 
always be a reference on the guest memory and domain. So no destruction.
> Is it ok to call domain_vpl011_deinit() inside domain_kill?
domain_kill is a arch agnostic function. You want to call 
domain_vpl011_init from domain_relinquish_resources. I would do in the 
case RELMEM_not_started after iommu_release_dt_devices is called.
Cheers,

--
Julien Grall

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