Commit f9940416 authored Sep 27, 2023 by Marc Zyngier Committed by Oliver Upton Sep 30, 2023

KVM: arm64: Clarify the ordering requirements for vcpu/RD creation



It goes without saying, but it is probably better to spell it out:

If userspace tries to restore and VM, but creates vcpus and/or RDs
in a different order, the vcpu/RD mapping will be different. Yes,
our API is an ugly piece of crap and I can't believe that we missed
this.

If we want to relax the above, we'll need to define a new userspace
API that allows the mapping to be specified, rather than relying
on the kernel to perform the mapping on its own.

Reviewed-by: Zenghui Yu <yuzenghui@huawei.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20230927090911.3355209-12-maz@kernel.org


Signed-off-by: Oliver Upton <oliver.upton@linux.dev>

parent b5daffb1

Documentation/virt/kvm/devices/arm-vgic-v3.rst

+7 −0

Original line number	Diff line number	Diff line
		@@ -59,6 +59,13 @@ Groups:
		It is invalid to mix calls with KVM_VGIC_V3_ADDR_TYPE_REDIST and
		KVM_VGIC_V3_ADDR_TYPE_REDIST_REGION attributes.

		Note that to obtain reproducible results (the same VCPU being associated
		with the same redistributor across a save/restore operation), VCPU creation
		order, redistributor region creation order as well as the respective
		interleaves of VCPU and region creation MUST be preserved. Any change in
		either ordering may result in a different vcpu_id/redistributor association,
		resulting in a VM that will fail to run at restore time.

		Errors:

		======= =============================================================