x86: improve reporting through XENMEM_machine_memory_map

Since Dom0 derives machine address ranges usable for assigning PCI
device resources from the output of this sub-hypercall, Xen should
make
sure it properly reports all ranges not suitable for this (as either
reserved or unusable):
- RAM regions excluded via command line option
- memory regions used by Xen itself (LAPIC, IOAPICs)

While the latter should generally already be excluded by the BIOS
provided E820 table, this apparently isn't always the case at least
for IOAPICs, and with Linux having got changed to account for this it
seems to make sense to also do so in Xen.

Generally the HPET range should also be excluded here, but since it
isn't being reflected in Dom0's iomem_caps (and can't be, as it's a
sub-page range) I wasn't sure whether adding explicit code for doing
so would be reasonable.

Signed-off-by: Jan Beulich <jbeulich@novell.com>

1 files changed, 3 insertions, 0 deletions

diff --git a/xen/include/xen/rangeset.h b/xen/include/xen/rangeset.h
index d4a8e00393..4219c079ef 100644
--- a/xen/include/xen/rangeset.h
+++ b/xen/include/xen/rangeset.h
@@ -53,6 +53,9 @@ int __must_check rangeset_remove_range(
     struct rangeset *r, unsigned long s, unsigned long e);
 int __must_check rangeset_contains_range(
     struct rangeset *r, unsigned long s, unsigned long e);
+int rangeset_report_ranges(
+    struct rangeset *r, unsigned long s, unsigned long e,
+    int (*cb)(unsigned long s, unsigned long e, void *), void *ctxt);
 
 /* Add/remove/query a single number. */
 int __must_check rangeset_add_singleton(