Hiya,
QEMU (ab)uses the kvm encoding of system register ids in the migration stream. As we
implement support for FEAT_D128, it would be good to agree on an encoding for the 128-bit
registers so that we can avoid complications with migration later.
I don't think this is terribly complicated. Simply adjust the value in the
KVM_REG_SIZE_MASK field from U64 to U128. E.g.
PAR_EL1 (64-bit) (__ARM64_SYS_REG(3, 0, 7, 4, 0) | KVM_REG_SIZE_U64)
PAR_EL1 (128-bit) (__ARM64_SYS_REG(3, 0, 7, 4, 0) | KVM_REG_SIZE_U128)
This will currently be cleanly rejected by index_to_params, resulting in ENOENT for the
ioctl. When KVM grows support for D128 guests, kvm_sys_reg_{get,set}_user can select the
read/write code path based on reg->id & KVM_REG_SIZE_MASK.
Comments?
r~
