On 02.05.23 15:56, Matthew Rosato wrote:
On 5/2/23 9:50 AM, Jason Gunthorpe wrote:
On Tue, May 02, 2023 at 03:47:43PM +0200, David Hildenbrand wrote:
Eventually we want to implement a mechanism where we can dynamically pin in response to RPCIT.
Okay, so IIRC we'll fail starting the domain early, that's good. And if we
pin all guest memory (instead of small pieces dynamically), there is little
existing use for file-backed RAM in such zPCI configurations (because memory
cannot be reclaimed either way if it's all pinned), so likely there are no
real existing users.
Right, this is VFIO, the physical HW can't tolerate not having pinned
memory, so something somewhere is always pinning it.
I might have mis-explained above.
With iommufd nesting, we will pin everything upfront as a starting point.
The current usage of vfio type1 iommu for s390 does not pin the entirety of guest memory upfront, it happens as guest RPCITs occur / type1 mappings are made.
... so, after the domain started successfully on the libvirt/QEMU side ? :/
It would be great to confirm that. There might be a BUG in patch #2 (see
my reply to patch #2) that might not allow you to reproduce it right now.
--
Thanks,
David / dhildenb
