Re: [PATCH v3 2/4] xen/arm: Alloc XenStore page for Dom0less DomUs from hypervisor

[Jürgen Groß <jgross@xxxxxxxx>]

On 24.05.24 15:58, Julien Grall wrote:
> Hi Henry,
>
> + Juergen as the Xenstore maintainers. I'd like his opinion on the approach. The 
> documentation of the new logic is in:
> https://lore.kernel.org/xen-devel/20240517032156.1490515-5-xin.wang2@xxxxxxx/
>
> FWIW I am happy in principle with the logic (this is what we discussed on the 
> call last week). Some comments below.
I'm not against this logic, but I'm wondering why it needs to be so
complicated.

Can't the domU itself allocate the Xenstore page from its RAM pages,
write the PFN into the Xenstore grant tab entry, and then make it
public via setting HVM_PARAM_STORE_PFN?

The init-dom0less application could then check HVM_PARAM_STORE_PFN
being set and call XS_introduce_domain.

Note that at least C-xenstored does not need the PFN of the Xenstore
page, as it is just using GNTTAB_RESERVED_XENSTORE for mapping the
page.


Juergen