(+ Stefano, Wei and Ian)
Hello,
Apologies for the late answer.
First of all, please avoid sending e-mail using HTML encoding. E-mail on
mailing should only be plain text.
On 3/20/19 9:28 AM, rambl...@sina.com wrote:
> On 18/03/2019 06:50, rambl...@sina.com wrote:
> > Hello,
> Hello,
> > I'm researching xen for automotive use case and I see a
presentation called:
> > "Design and Implementation of Automotive Virtualization Based on
Xen - Sung-Min
> > Lee, Samsung Electronics"
> > on Xen Developer and Design Summit 2018.
> >
> > I'm interesting in the modification of fault recovery scenario on
P9~P11, it
> > introduced a new hypercall called XEN_DOMCTL_samsung_reset.
> If I recall correctly the talk, XEN_DOMCTL_samsung_reset is doing
exactly the
> same as XEN_DOMCTL_soft_reset. The later is not yet implemented on
Arm, I can
> provide guidelines if you are interested to implement it.
Thank you for your reply!
It will be very useful if there is some guide for implement the soft_reset.
(See below).
And are there any plan for official implementation of this function on ARM?
I am not aware of anyone working on the implementation for Arm. I would
be happy to review any patch series sent.
> Where can I find some code or tutorial for this modification? Has the
code been
> released?
> Your best bet would be to contact the speaker.
> Best regards,
> --
> Julien Grall
I check the code in xl, in function libxl_domain_soft_reset there is a
check that
if (info->type != LIBXL_DOMAIN_TYPE_HVM) return ERROR_INVAL;
So the ARM use PVH type can't use this function.
AFAICT, this is HVM only because the softreset code relies on the
presence of a device-model. PVH guest does not have a device model, the
code at the end of the function do_domain_soft_reset would need to be
adapted to remove any reference on the device model.
Are there any guide or sample code for implementation of this feature?
I haven't fully though about the soft reset on Arm.
From my understanding, for a first implementation, replacing the domain
shared info page with a new page (see the implementation in the x86
version of arch_domain_create) should be sufficient. You should be able
to soft_reset your domain afterwards.
For a more robust implementation, I think we need to warn if foreign
mappings are still present because they are mapping to another guest.
There might be interesting thing happening if they are still present.
You would need to go through the P2M and check if there are a foreign
mappings in place.
There might be other mappings to take care of (i.e grant-table...) but I
didn't have time to look whether it is strictly necessary yet.
I have CCed some person that should be able to give feedback on libxl
and complete if I miss anything.
Cheers,
--
Julien Grall
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