Re: [for-4.15][PATCH v2 1/5] xen/x86: p2m: Don't map the special pages in the IOMMU page-tables

[Jan Beulich <jbeulich@xxxxxxxx>]

On 10.02.2021 12:54, Roger Pau Monné wrote:
> On Wed, Feb 10, 2021 at 11:48:40AM +0000, Julien Grall wrote:
>> It feels wrong to me to setup a per-domain mapping when initializing the
>> first vCPU.
>>
>> But, I was under the impression that there is plan to remove
>> XEN_DOMCTL_max_vcpus. So it would only buy just a bit of time...
> 
> I was also under that impression. We could setup the lapic access page
> at vlapic_init for the BSP (which is part of XEN_DOMCTL_max_vcpus
> ATM).
> 
> But then I think there should be some kind of check to prevent
> populating either the CPU or the IOMMU page tables at domain creation
> hypercall, and so the logic to free CPU table tables on failure could
> be removed.

I can spot paging_final_teardown() on an error path there, but I
don't suppose that's what you mean? I guess I'm not looking in
the right place (there are quite a few after all) ...

Jan