tree 4bdefb73667c09dec5cccd26c97cf59f37f2cd92
parent 839d90357b7ce6b129045d28ac22bd3a247e2350
author Marc Zyngier <maz@kernel.org> 1692706690 +0100
committer Marc Zyngier <maz@kernel.org> 1697126121 +0100

KVM: arm64: timers: Correctly handle TGE flip with CNTPOFF_EL2

Contrary to common belief, HCR_EL2.TGE has a direct and immediate
effect on the way the EL0 physical counter is offset. Flipping
TGE from 1 to 0 while at EL2 immediately changes the way the counter
compared to the CVAL limit.

This means that we cannot directly save/restore the guest's view of
CVAL, but that we instead must treat it as if CNTPOFF didn't exist.
Only in the world switch, once we figure out that we do have CNTPOFF,
can we must the offset back and forth depending on the polarity of
TGE.

Fixes: 2b4825a86940 ("KVM: arm64: timers: Use CNTPOFF_EL2 to offset the physical timer")
Reported-by: Ganapatrao Kulkarni <gankulkarni@os.amperecomputing.com>
Tested-by: Ganapatrao Kulkarni <gankulkarni@os.amperecomputing.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>