On 09/05/2016 18:18, Paul Durrant wrote:
> Since Xen will correctly handle accesses to unimplemented I/O ports (by
> returning all 1's for reads and ignoring writes) there is no need for
> QEMU to register backgroud I/O sections.
>
> This patch therefore adds checks to xen_io_add/del so that sections with
> memory-region ops pointing at 'unassigned_io_ops' are ignored.
>
> Signed-off-by: Paul Durrant <paul.durr...@citrix.com>
> Cc: Stefano Stabellini <sstabell...@kernel.org>
> Cc: Anthony Perard <anthony.per...@citrix.com>
> Cc: Paolo Bonzini <pbonz...@redhat.com>
> ---
> xen-hvm.c | 12 ++++++++++--
> 1 file changed, 10 insertions(+), 2 deletions(-)
>
> diff --git a/xen-hvm.c b/xen-hvm.c
> index 039680a..8ab44f0 100644
> --- a/xen-hvm.c
> +++ b/xen-hvm.c
> @@ -510,8 +510,12 @@ static void xen_io_add(MemoryListener *listener,
> MemoryRegionSection *section)
> {
> XenIOState *state = container_of(listener, XenIOState, io_listener);
> + MemoryRegion *mr = section->mr;
>
> - memory_region_ref(section->mr);
> + if (mr->ops == &unassigned_io_ops)
> + return;
Missing braces, same in xen_io_del. Otherwise looks ok.
Paolo
> + memory_region_ref(mr);
>
> xen_map_io_section(xen_xc, xen_domid, state->ioservid, section);
> }
> @@ -520,10 +524,14 @@ static void xen_io_del(MemoryListener *listener,
> MemoryRegionSection *section)
> {
> XenIOState *state = container_of(listener, XenIOState, io_listener);
> + MemoryRegion *mr = section->mr;
> +
> + if (mr->ops == &unassigned_io_ops)
> + return;
>
> xen_unmap_io_section(xen_xc, xen_domid, state->ioservid, section);
>
> - memory_region_unref(section->mr);
> + memory_region_unref(mr);
> }
>
> static void xen_device_realize(DeviceListener *listener,
>
