[RFC PATCH v2 11/58] KVM: arm64: pkvm: Add pkvm_udelay()

[Quentin Perret]

On Thursday 12 Dec 2024 at 18:03:35 (+0000), Mostafa Saleh wrote:
> From: Jean-Philippe Brucker <jean-philippe at linaro.org>
> 
> Add a simple delay loop for drivers.
> 
> This could use more work. It should be possible to insert a wfe and save
> power, but I haven't studied whether it is safe to do so with the host
> in control of the event stream. The SMMU driver will use wfe anyway for
> frequent waits (provided the implementation can send command queue
> events).

Mooh, I'm thoroughly hating that we need this -- pKVM is non preemptible
so we better not wait for too long.

I can surely figure it out from the following patches, but could you
please expand on the use-case?

On a side note I'm not too worried about the power impact of not having
a wfe in there, again we better not be spinning for long enough that
power starts to be noticeable.