[PATCH v2 5/6] xen/arm: unpopulate memory when domain is static

[Penny Zheng <Penny.Zheng@arm.com>]

Today when a domain unpopulates the memory on runtime, they will always
hand the memory back to the heap allocator. And it will be a problem if domain
is static.

Pages as guest RAM for static domain shall be reserved to only this domain
and not be used for any other purposes, so they shall never go back to heap
allocator.

This commit puts reserved pages on the new list resv_page_list only after
having taken them off the "normal" list, when the last ref dropped.

Signed-off-by: Penny Zheng <penny.zheng@arm.com>
---
v2 changes:
- put reserved pages on resv_page_list after having taken them off
the "normal" list
---
 xen/arch/arm/include/asm/mm.h | 17 +++++++++++++++++
 xen/common/domain.c           |  4 ++++
 xen/include/xen/sched.h       |  6 ++++++
 3 files changed, 27 insertions(+)

diff --git a/xen/arch/arm/include/asm/mm.h b/xen/arch/arm/include/asm/mm.h
index 424aaf2823..a2dde01cfa 100644
--- a/xen/arch/arm/include/asm/mm.h
+++ b/xen/arch/arm/include/asm/mm.h
@@ -358,6 +358,23 @@ void clear_and_clean_page(struct page_info *page);
 
 unsigned int arch_get_dma_bitsize(void);
 
+/*
+ * Put free pages on the resv page list after having taken them
+ * off the "normal" page list, when pages from static memory
+ */
+#ifdef CONFIG_STATIC_MEMORY
+#define arch_free_heap_page(d, pg) {                    \
+    if ( (pg)->count_info & PGC_reserved )              \
+    {                                                   \
+        page_list_del(pg, page_to_list(d, pg));         \
+        page_list_add_tail(pg, &(d)->resv_page_list);   \
+        (d)->resv_pages++;                              \
+    }                                                   \
+    else                                                \
+        page_list_del(pg, page_to_list(d, pg));         \
+}
+#endif
+
 #endif /*  __ARCH_ARM_MM__ */
 /*
  * Local variables:
diff --git a/xen/common/domain.c b/xen/common/domain.c
index 859cc13d3b..b499cf8d2c 100644
--- a/xen/common/domain.c
+++ b/xen/common/domain.c
@@ -605,6 +605,10 @@ struct domain *domain_create(domid_t domid,
     INIT_PAGE_LIST_HEAD(&d->page_list);
     INIT_PAGE_LIST_HEAD(&d->extra_page_list);
     INIT_PAGE_LIST_HEAD(&d->xenpage_list);
+#ifdef CONFIG_STATIC_MEMORY
+    INIT_PAGE_LIST_HEAD(&d->resv_page_list);
+#endif
+
 
     spin_lock_init(&d->node_affinity_lock);
     d->node_affinity = NODE_MASK_ALL;
diff --git a/xen/include/xen/sched.h b/xen/include/xen/sched.h
index 68eb08058e..85ef378752 100644
--- a/xen/include/xen/sched.h
+++ b/xen/include/xen/sched.h
@@ -376,6 +376,9 @@ struct domain
     struct page_list_head page_list;  /* linked list */
     struct page_list_head extra_page_list; /* linked list (size extra_pages) */
     struct page_list_head xenpage_list; /* linked list (size xenheap_pages) */
+#ifdef CONFIG_STATIC_MEMORY
+    struct page_list_head resv_page_list; /* linked list (size resv_pages) */
+#endif
 
     /*
      * This field should only be directly accessed by domain_adjust_tot_pages()
@@ -395,6 +398,9 @@ struct domain
 #ifdef CONFIG_MEM_PAGING
     atomic_t         paged_pages;       /* paged-out pages */
 #endif
+#ifdef CONFIG_STATIC_MEMORY
+    unsigned int     resv_pages;        /* reserved pages from static region. */
+#endif
 
     /* Scheduling. */
     void            *sched_priv;    /* scheduler-specific data */
-- 
2.25.1