David Gibson <da...@gibson.dropbear.id.au> writes: > qemu currently implements the hypercalls H_LOGICAL_CI_LOAD and > H_LOGICAL_CI_STORE as PAPR extensions. These are used by the SLOF firmware > for IO, because performing cache inhibited MMIO accesses with the MMU off > (real mode) is very awkward on POWER. > > This approach breaks when SLOF needs to access IO devices implemented > within KVM instead of in qemu. The simplest example would be virtio-blk > using an iothread, because the iothread / dataplane mechanism relies on > an in-kernel implementation of the virtio queue notification MMIO. > > To fix this, an in-kernel implementation of these hypercalls has been made, > however, the hypercalls still need to be enabled from qemu. This performs > the necessary calls to do so. > > Signed-off-by: David Gibson <da...@gibson.dropbear.id.au>
Reviewed-by: Nikunj A Dadhania <nik...@linux.vnet.ibm.com>
