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c268f204f7
Currently, when a nested MMU is repurposed for some other MMU context, KVM unmaps everything during vcpu_load() while holding the MMU lock for write. This is quite a performance bottleneck for large nested VMs, as all vCPU scheduling will spin until the unmap completes. Start punting the MMU cleanup to a vCPU request, where it is then possible to periodically release the MMU lock and CPU in the presence of contention. Ensure that no vCPU winds up using a stale MMU by tracking the pending unmap on the S2 MMU itself and requesting an unmap on every vCPU that finds it. Signed-off-by: Oliver Upton <oliver.upton@linux.dev> Link: https://lore.kernel.org/r/20241007233028.2236133-4-oliver.upton@linux.dev Signed-off-by: Marc Zyngier <maz@kernel.org>