KVM: arm/arm64: vgic: Fix GICC_PMR uaccess on GICv3 and clarify ABI
As an oversight, for GICv2, we accidentally export the GICC_PMR register
in the format of the GICH_VMCR.VMPriMask field in the lower 5 bits of a
word, meaning that userspace must always use the lower 5 bits to
communicate with the KVM device and must shift the value left by 3
places to obtain the actual priority mask level.
Since GICv3 supports the full 8 bits of priority masking in the ICH_VMCR,
we have to fix the value we export when emulating a GICv2 on top of a
hardware GICv3 and exporting the emulated GICv2 state to userspace.
Take the chance to clarify this aspect of the ABI.
Reviewed-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Christoffer Dall <cdall@linaro.org>
diff --git a/include/linux/irqchip/arm-gic.h b/include/linux/irqchip/arm-gic.h
index eafc965..dc30f3d 100644
--- a/include/linux/irqchip/arm-gic.h
+++ b/include/linux/irqchip/arm-gic.h
@@ -96,6 +96,9 @@
#define GICH_MISR_EOI (1 << 0)
#define GICH_MISR_U (1 << 1)
+#define GICV_PMR_PRIORITY_SHIFT 3
+#define GICV_PMR_PRIORITY_MASK (0x1f << GICV_PMR_PRIORITY_SHIFT)
+
#ifndef __ASSEMBLY__
#include <linux/irqdomain.h>