tree c9a13a5e7fb97a4cb63ae6264779a15b07969781
parent eb7081409f94a9a8608593d0fb63a1aa3d6f95d8
author Marc Zyngier <maz@kernel.org> 1670163742 +0000
committer Marc Zyngier <maz@kernel.org> 1670163742 +0000

KVM: arm64: Return MIDR_EL1 to userspace as seen on the vcpu thread

When booting, KVM sample the MIDR of the CPU it initialises on,
and keep this as the value that will forever be exposed to userspace.

However, this has nothing to do with the value that the guest will
see. On an asymetric system, this can result in userspace observing
weird things, specially if it has pinned the vcpus on a *different*
set of CPUs.

Instead, return the MIDR value for the vpcu we're currently on and
that the vcpu will observe if it has been pinned onto that CPU.

For symmetric systems, this changes nothing. For asymmetric machines,
they will observe the correct MIDR value at the point of the call.

Reported-by: Akihiko Odaki <akihiko.odaki@gmail.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>