[PATCH 05/10] xen/arm: introduce alloc_staticmem_pages

[Penny Zheng <penny.zheng@xxxxxxx>]

alloc_staticmem_pages is designated to allocate nr_pfns contiguous
pages of static memory. And it is the equivalent of alloc_heap_pages
for static memory.
This commit only covers allocating at specified starting address.

For each page, it shall check if the page is reserved
(PGC_reserved) and free. It shall also do a set of necessary
initialization, which are mostly the same ones in alloc_heap_pages,
like, following the same cache-coherency policy and turning page
status into PGC_state_used, etc.

Signed-off-by: Penny Zheng <penny.zheng@xxxxxxx>
---
 xen/common/page_alloc.c | 64 +++++++++++++++++++++++++++++++++++++++++
 1 file changed, 64 insertions(+)

diff --git a/xen/common/page_alloc.c b/xen/common/page_alloc.c
index 58b53c6ac2..adf2889e76 100644
--- a/xen/common/page_alloc.c
+++ b/xen/common/page_alloc.c
@@ -1068,6 +1068,70 @@ static struct page_info *alloc_heap_pages(
     return pg;
 }
 
+/*
+ * Allocate nr_pfns contiguous pages, starting at #start, of static memory.
+ * It is the equivalent of alloc_heap_pages for static memory
+ */
+static struct page_info *alloc_staticmem_pages(unsigned long nr_pfns,
+                                                paddr_t start,
+                                                unsigned int memflags)
+{
+    bool need_tlbflush = false;
+    uint32_t tlbflush_timestamp = 0;
+    unsigned int i;
+    struct page_info *pg;
+    mfn_t s_mfn;
+
+    /* For now, it only supports allocating at specified address. */
+    s_mfn = maddr_to_mfn(start);
+    pg = mfn_to_page(s_mfn);
+    if ( !pg )
+        return NULL;
+
+    for ( i = 0; i < nr_pfns; i++)
+    {
+        /*
+         * Reference count must continuously be zero for free pages
+         * of static memory(PGC_reserved).
+         */
+        ASSERT(pg[i].count_info & PGC_reserved);
+        if ( (pg[i].count_info & ~PGC_reserved) != PGC_state_free )
+        {
+            printk(XENLOG_ERR
+                    "Reference count must continuously be zero for free pages"
+                    "pg[%u] MFN %"PRI_mfn" c=%#lx t=%#x\n",
+                    i, mfn_x(page_to_mfn(pg + i)),
+                    pg[i].count_info, pg[i].tlbflush_timestamp);
+            BUG();
+        }
+
+        if ( !(memflags & MEMF_no_tlbflush) )
+            accumulate_tlbflush(&need_tlbflush, &pg[i],
+                                &tlbflush_timestamp);
+
+        /*
+         * Reserve flag PGC_reserved and change page state
+         * to PGC_state_inuse.
+         */
+        pg[i].count_info = (pg[i].count_info & PGC_reserved) | PGC_state_inuse;
+        /* Initialise fields which have other uses for free pages. */
+        pg[i].u.inuse.type_info = 0;
+        page_set_owner(&pg[i], NULL);
+
+        /*
+         * Ensure cache and RAM are consistent for platforms where the
+         * guest can control its own visibility of/through the cache.
+         */
+        flush_page_to_ram(mfn_x(page_to_mfn(&pg[i])),
+                            !(memflags & MEMF_no_icache_flush));
+    }
+
+    if ( need_tlbflush )
+        filtered_flush_tlb_mask(tlbflush_timestamp);
+
+    return pg;
+}
+
 /* Remove any offlined page in the buddy pointed to by head. */
 static int reserve_offlined_page(struct page_info *head)
 {
-- 
2.25.1