Currently the default PCI host bridge for the 'pseries' machine type is
constructed with its IO windows in the 1TiB..(1TiB + 64GiB) range in
guest memory space. This means that if > 1TiB of guest RAM is specified,
the RAM will collide with the PCI IO windows, causing serious problems.
Problems won't be obvious until guest RAM goes a bit beyond 1TiB, because
there's a little unused space at the bottom of the area reserved for PCI,
but essentially this means that > 1TiB of RAM has never worked with the
pseries machine type.
This patch fixes this by altering the placement of PHBs on large-RAM VMs.
Instead of always placing the first PHB at 1TiB, it is placed at the next
1 TiB boundary after the maximum RAM address.
Technically, this changes behaviour in a migration-breaking way for
existing machines with > 1TiB maximum memory, but since having > 1 TiB
memory was broken anyway, this seems like a reasonable trade-off.
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Reviewed-by: Laurent Vivier <lvivier@redhat.com>
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