On 10/26/21 18:06, David Hildenbrand wrote:
> memory_region_is_mapped() currently does not return "true" when a memory
> region is mapped via an alias.
>
> Assuming we have:
> alias (A0) -> alias (A1) -> region (R0)
> Mapping A0 would currently only make memory_region_is_mapped() succeed
> on A0, but not on A1 and R0.
>
> Let's fix that by adding a "mapped_via_alias" counter to memory regions and
> updating it accordingly when an alias gets (un)mapped.
>
> I am not aware of actual issues, this is rather a cleanup to make it
> consistent.
>
> Signed-off-by: David Hildenbrand <da...@redhat.com>
> ---
> include/exec/memory.h | 1 +
> softmmu/memory.c | 12 +++++++++++-
> 2 files changed, 12 insertions(+), 1 deletion(-)
>
> diff --git a/include/exec/memory.h b/include/exec/memory.h
> index a185b6dcb8..35382d9870 100644
> --- a/include/exec/memory.h
> +++ b/include/exec/memory.h
> @@ -707,6 +707,7 @@ struct MemoryRegion {
> const MemoryRegionOps *ops;
> void *opaque;
> MemoryRegion *container;
> + int mapped_via_alias; /* Mapped via an alias, container might be NULL */
> Int128 size;
> hwaddr addr;
> void (*destructor)(MemoryRegion *mr);
> diff --git a/softmmu/memory.c b/softmmu/memory.c
> index e5826faa0c..17ca896c38 100644
> --- a/softmmu/memory.c
> +++ b/softmmu/memory.c
> @@ -2524,8 +2524,13 @@ static void
> memory_region_add_subregion_common(MemoryRegion *mr,
> hwaddr offset,
> MemoryRegion *subregion)
> {
> + MemoryRegion *alias;
> +
> assert(!subregion->container);
> subregion->container = mr;
> + for (alias = subregion->alias; alias; alias = alias->alias) {
> + alias->mapped_via_alias++;
> + }
> subregion->addr = offset;
> memory_region_update_container_subregions(subregion);
> }
> @@ -2550,9 +2555,14 @@ void memory_region_add_subregion_overlap(MemoryRegion
> *mr,
> void memory_region_del_subregion(MemoryRegion *mr,
> MemoryRegion *subregion)
> {
> + MemoryRegion *alias;
> +
> memory_region_transaction_begin();
> assert(subregion->container == mr);
> subregion->container = NULL;
> + for (alias = subregion->alias; alias; alias = alias->alias) {
> + alias->mapped_via_alias--;
assert(alias->mapped_via_alias >= 0);
> + }
> QTAILQ_REMOVE(&mr->subregions, subregion, subregions_link);
> memory_region_unref(subregion);
> memory_region_update_pending |= mr->enabled && subregion->enabled;
> @@ -2649,7 +2659,7 @@ static FlatRange *flatview_lookup(FlatView *view,
> AddrRange addr)
>
> bool memory_region_is_mapped(MemoryRegion *mr)
> {
> - return mr->container ? true : false;
> + return !!mr->container || mr->mapped_via_alias;
> }
>
> /* Same as memory_region_find, but it does not add a reference to the
>
Reviewed-by: Philippe Mathieu-Daudé <phi...@redhat.com>
