arm64: kvm: Unmask PMR before entering guest

Interrupts masked by ICC_PMR_EL1 will not be signaled to the CPU. This
means that hypervisor will not receive masked interrupts while running a
guest.

We need to make sure that all maskable interrupts are masked from the
time we call local_irq_disable() in the main run loop, and remain so
until we call local_irq_enable() after returning from the guest, and we
need to ensure that we see no interrupts at all (including pseudo-NMIs)
in the middle of the VM world-switch, while at the same time we need to
ensure we exit the guest when there are interrupts for the host.

We can accomplish this with pseudo-NMIs enabled by:
  (1) local_irq_disable: set the priority mask
  (2) enter guest: set PSTATE.I
  (3)              clear the priority mask
  (4) eret to guest
  (5) exit guest:  set the priotiy mask
                   clear PSTATE.I (and restore other host PSTATE bits)
  (6) local_irq_enable: clear the priority mask.

Signed-off-by: Julien Thierry <[email protected]>
Acked-by: Catalin Marinas <[email protected]>
Reviewed-by: Marc Zyngier <[email protected]>
Reviewed-by: Christoffer Dall <[email protected]>
Cc: Christoffer Dall <[email protected]>
Cc: Marc Zyngier <[email protected]>
Cc: Will Deacon <[email protected]>
Cc: [email protected]
Signed-off-by: Catalin Marinas <[email protected]>

0 files changed, 0 insertions, 0 deletions