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memory: Make memory_region_is_mapped() succeed when mapped via an alias

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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.

Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Reviewed-by: Peter Xu <peterx@redhat.com>
Signed-off-by: David Hildenbrand <david@redhat.com>
Message-Id: <20211102164317.45658-3-david@redhat.com>
Signed-off-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
This commit is contained in:
David Hildenbrand 2021-11-02 17:43:16 +01:00 committed by Philippe Mathieu-Daudé
parent eef3a7abff
commit 5ead62185d
2 changed files with 13 additions and 1 deletions
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1
include/exec/memory.h
View File

@ -738,6 +738,7 @@ 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);

13
softmmu/memory.c
View File

@ -2545,8 +2545,13 @@ 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);
}
@ -2571,9 +2576,15 @@ 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;
@ -2670,7 +2681,7 @@ 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