We are exporting the format of the priority field as it's stored in the GICH_VMCR.VMPriMask field using the lower five bits when accessing register state using the GICC_PMR offset. This is unfortunate, but it's ABI already, so we simply have to make it clear.
Signed-off-by: Christoffer Dall <[email protected]> --- Documentation/virtual/kvm/devices/arm-vgic.txt | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/Documentation/virtual/kvm/devices/arm-vgic.txt b/Documentation/virtual/kvm/devices/arm-vgic.txt index 76e61c8..975a904 100644 --- a/Documentation/virtual/kvm/devices/arm-vgic.txt +++ b/Documentation/virtual/kvm/devices/arm-vgic.txt @@ -83,6 +83,12 @@ Groups: Bits for undefined preemption levels are RAZ/WI. + For historical reasons we 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. + Limitations: - Priorities are not implemented, and registers are RAZ/WI - Currently only implemented for KVM_DEV_TYPE_ARM_VGIC_V2. -- 2.9.0 _______________________________________________ kvmarm mailing list [email protected] https://lists.cs.columbia.edu/mailman/listinfo/kvmarm
