On 2022-02-01 16:51, Russell King (Oracle) wrote:

On Fri, Jan 28, 2022 at 12:18:23PM +0000, Marc Zyngier wrote:

quoted

HCR_EL2.E2H is nasty, as a flip of this bit completely changes the way
we deal with a lot of the state. So when the guest flips this bit
(sysregs are live), do the put/load dance so that we have a consistent
state.

Yes, this is slow. Don't do it.

I'd hope this is very unlikely!

A guest OS would probably do it once per CPU bring-up. So I'm
not too bothered about the speed. But that's only one of the
many cases where we need to do this put/load game.

At this stage, we don't care too much. But the last two patches
give you a glimpse of what sort of fine-grained optimisation
we will eventually want to do for this not to suck too much.

But again, this is NV, and it gives a whole new sense to "being
slow".

quoted

Suggested-by: Alexandru Elisei <redacted>
Signed-off-by: Marc Zyngier <maz@kernel.org>

Reviewed-by: Russell King (Oracle) <redacted>

Thanks,

         M.
-- 
Jazz is not dead. It just smells funny...

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