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Re: [Xen-devel] [v7][RFC][PATCH 06/13] hvmloader/ram: check if guest memory is out of reserved device memory maps

On 2014/11/3 20:34, Jan Beulich wrote:
On 03.11.14 at 12:58, <tiejun.chen@xxxxxxxxx> wrote:
Firstly we have a rule that we just allow all devices associated one
RMRR to be assign same VM, right? So I mean while we create VM, we
always call current hypercall but inside hypercall, Xen can know which
devices will be assigned to this VM.

I.e. the hypercall (at least optionally) becomes per-domain rather
than global. And you imply that device assignment happens
before memory getting populated (which likely can be arranged

I tried to find a clue about this point but unfortunately I can't trace when we assign device exactly. But in theory, based on your hint I prefer the device assignment should follow memory getting populated. Because when we add a device, we need to create iommu map so this means at this moment the guest should already finish populating memory, right?


for in the tool stack if that's not already the case, but which isn't
currently mandated by the hypervisor).


So Xen still lookup that RMRR list
but now Xen would check if these RMRR belongs to that device we want to
assign this domain. If yes, we just let that callback go through these
RMRR info from that list but exclude other unrelated RMRR. If not, we
don't go through any RMRR info so that 'nr_entries' is also zero.


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