Re: [Xen-devel] [PATCH v2 02/21] xen/arm: make allocate_memory work for non 1:1 mapped guests

[Stefano Stabellini <sstabellini@xxxxxxxxxx>]

On Mon, 23 Jul 2018, Andrii Anisov wrote:
> Hello Stefano,
> 
> 
> On 07.07.18 02:11, Stefano Stabellini wrote:
> > Extend allocate_memory to work for non 1:1 mapped domUs. Specifically,
> > memory allocated for domU will be mapped into the domU pseudo-physical
> > address space at the appropriate addresses according to the guest memory
> > map: GUEST_RAM0_BASE and GUEST_RAM1_BASE.
> I would speculate about GUEST_RAMx_BASE and GUEST_RAMx_SIZE macros. Those
> values might not fit the real SoC memory map. And it becomes a problem once we
> decided to assign some peripheral directly to the guest because a RAM space
> specified to VM would overlap with IO range of the assigned device.
> In my practice, we always align those macros with the SoC memory map. This
> becomes more convenient and practical than IO remapping.
> 
> It might be the moment to get those values configurable for the guests. At
> least for those, which are configured from the device tree. Here naturally fit
> making `memory` property similar to `reg` - the list of <base, size> values.

Yes, you are right. Those value should be made configurable. It is
already on my roadmap. But I would keep it separate from this series: it
is not just about the position of RAM in the guest address space, also
the GIC and timer addresses need to be configurable. I usually refer to
this (future) feature as arbitrary guest memory map.

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