path: root/include
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authorRoger Pau Monne <roger.pau@citrix.com>2020-09-01 10:33:26 +0200
committerJuergen Gross <jgross@suse.com>2020-09-04 10:00:01 +0200
commit9e2369c06c8a181478039258a4598c1ddd2cadfa (patch)
tree4a5834c69de9fb3864acd24e078dd765fb69b21c /include
parentmemremap: rename MEMORY_DEVICE_DEVDAX to MEMORY_DEVICE_GENERIC (diff)
xen: add helpers to allocate unpopulated memory
To be used in order to create foreign mappings. This is based on the ZONE_DEVICE facility which is used by persistent memory devices in order to create struct pages and kernel virtual mappings for the IOMEM areas of such devices. Note that on kernels without support for ZONE_DEVICE Xen will fallback to use ballooned pages in order to create foreign mappings. The newly added helpers use the same parameters as the existing {alloc/free}_xenballooned_pages functions, which allows for in-place replacement of the callers. Once a memory region has been added to be used as scratch mapping space it will no longer be released, and pages returned are kept in a linked list. This allows to have a buffer of pages and prevents resorting to frequent additions and removals of regions. If enabled (because ZONE_DEVICE is supported) the usage of the new functionality untangles Xen balloon and RAM hotplug from the usage of unpopulated physical memory ranges to map foreign pages, which is the correct thing to do in order to avoid mappings of foreign pages depend on memory hotplug. Note the driver is currently not enabled on Arm platforms because it would interfere with the identity mapping required on some platforms. Signed-off-by: Roger Pau Monné <roger.pau@citrix.com> Reviewed-by: Juergen Gross <jgross@suse.com> Link: https://lore.kernel.org/r/20200901083326.21264-4-roger.pau@citrix.com Signed-off-by: Juergen Gross <jgross@suse.com>
Diffstat (limited to 'include')
1 files changed, 9 insertions, 0 deletions
diff --git a/include/xen/xen.h b/include/xen/xen.h
index 19a72f591e2b..43efba045acc 100644
--- a/include/xen/xen.h
+++ b/include/xen/xen.h
@@ -52,4 +52,13 @@ bool xen_biovec_phys_mergeable(const struct bio_vec *vec1,
extern u64 xen_saved_max_mem_size;
+int xen_alloc_unpopulated_pages(unsigned int nr_pages, struct page **pages);
+void xen_free_unpopulated_pages(unsigned int nr_pages, struct page **pages);
+#define xen_alloc_unpopulated_pages alloc_xenballooned_pages
+#define xen_free_unpopulated_pages free_xenballooned_pages
+#include <xen/balloon.h>
#endif /* _XEN_XEN_H */