[Xen-devel] [PATCH v2 0/8] xen: arm: Use super pages in p2m

[Ian Campbell <Ian.Campbell@xxxxxxxxxx>]

The following series adds support for superpage mappings (1G and 2M) in
the p2m for dom0 and domU.

At the moment it is not possible to allocate 1G regions to guests,
because this is gated on multipage_allocation_permitted() which
currently (incorrectly) returns false for dom0 on ARM. This is fixed by
Arianna's "arch/arm: domain build: let dom0 access I/O memory of mapped
devices" (which initialises iomem_caps for dom0).

On a 32-bit platform this causes the overhead of kernbench vs. native to
drop from 8-9% to 1.5-3% (it's basically the same for both dom0 and
domU).

I couldn't get my 64-bit platform to boot natively for some reason but
in absolute terms kernbench improved by ~5% (domU) to ~15% (dom0).

Changes in v2:
 - Juliens review comments
 - Added "xen: arm: allocate more than one bank for 1:1 domain 0 if 
   needed" (not strictly related...)

Ian.


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