Re: [Xen-devel] [PATCH v4 3/4] dom0/pvh: change the order of the MMCFG initialization

[Roger Pau Monné <roger.pau@xxxxxxxxxx>]

On Wed, Aug 08, 2018 at 06:35:47AM -0600, Jan Beulich wrote:
> >>> On 08.08.18 at 12:07, <roger.pau@xxxxxxxxxx> wrote:
> > So it's done before the iommu is initialized. This is required in
> > order to be able to fetch the MMCFG regions from the domain struct.
> 
> Is this a useful change to make? Regions not reported through the MCFG
> table will need punching holes anyway, so why not punch holes uniformly
> in all cases, allowing the hole punching code to be tested even on systems
> without non-boot-time-available regions?

I can add this hole-punching code to register_vpci_mmcfg_handler so I
can remove this reordering.

I'm however struggling to find a function that will set a p2m range to
p2m_invalid. All the functions that I find to deal with this assume
that you know the memory type you are trying to remove (for example
clear_identity_p2m_entry) and fail if the current type is different
than expected.

In this case it's quite likely that the MMCFG region is not mapped to
anything, should I introduce a new helper that sets a p2m range to
p2m_invalid regardless of the current type?

Thanks, Roger.

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