On 2022-02-01 16:51, Russell King (Oracle) wrote:
On Fri, Jan 28, 2022 at 12:18:23PM +0000, Marc Zyngier wrote:
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".
Suggested-by: Alexandru Elisei <alexandru.elisei@xxxxxxx>
Signed-off-by: Marc Zyngier <maz@xxxxxxxxxx>
Reviewed-by: Russell King (Oracle) <rmk+kernel@xxxxxxxxxxxxxxx>
Thanks,
M.
--
Jazz is not dead. It just smells funny...
