tree d6ac56a798b25c3537e2df96422b18020bb20823
parent e324c4dc4a5991d5b1171f434884a4026345e4b4
author Marc Zyngier <marc.zyngier@arm.com> 1440604842 +0100
committer Thomas Gleixner <tglx@linutronix.de> 1440688429 +0200

irqchip/GICv3: Convert to EOImode == 1

So far, GICv3 has been used in with EOImode == 0. The effect of this
mode is to perform the priority drop and the deactivation of the
interrupt at the same time.

While this works perfectly for Linux (we only have a single priority),
it causes issues when an interrupt is forwarded to a guest, and when
we want the guest to perform the EOI itself.

For this case, the GIC architecture provides EOImode == 1, where:
- A write to ICC_EOIR1_EL1 drops the priority of the interrupt and
  leaves it active. Other interrupts at the same priority level can
  now be taken, but the active interrupt cannot be taken again
- A write to ICC_DIR_EL1 marks the interrupt as inactive, meaning
  it can now be taken again.

This patch converts the driver to be able to use this new mode,
depending on whether or not the kernel can behave as a hypervisor.
No feature change.

Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Reviewed-and-tested-by: Eric Auger <eric.auger@linaro.org>
Cc: Christoffer Dall <christoffer.dall@linaro.org>
Cc: Jiang Liu <jiang.liu@linux.intel.com>
Cc: <linux-arm-kernel@lists.infradead.org>
Cc: kvmarm@lists.cs.columbia.edu
Cc: Jason Cooper <jason@lakedaemon.net>
Link: http://lkml.kernel.org/r/1440604845-28229-2-git-send-email-marc.zyngier@arm.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>