[PATCH v2] xen/arm: don't assign domU static-mem to dom0 as reserved-memory

[Stefano Stabellini <sstabellini@xxxxxxxxxx>]

From: Stefano Stabellini <stefano.stabellini@xxxxxxxxxx>

DomUs static-mem ranges are added to the reserved_mem array for
accounting, but they shouldn't be assigned to dom0 as the other regular
reserved-memory ranges in device tree.

In make_memory_nodes, fix the error by skipping banks with xen_domain
set to true in the reserved-memory array. Also make sure to use the
first valid (!xen_domain) start address for the memory node name.

Fixes: 41c031ff437b ("xen/arm: introduce domain on Static Allocation")
Signed-off-by: Stefano Stabellini <stefano.stabellini@xxxxxxxxxx>
Release-Acked-by: Ian Jackson <iwj@xxxxxxxxxxxxxx>

---
Changes in v2:
- improve commit message
- improve in-code comment
- update nr_cells appropriately
---
 xen/arch/arm/domain_build.c | 23 +++++++++++++++++------
 1 file changed, 17 insertions(+), 6 deletions(-)

diff --git a/xen/arch/arm/domain_build.c b/xen/arch/arm/domain_build.c
index 9e92b640cd..c81a2bdfef 100644
--- a/xen/arch/arm/domain_build.c
+++ b/xen/arch/arm/domain_build.c
@@ -862,21 +862,25 @@ static int __init make_memory_node(const struct domain *d,
 {
     int res, i;
     int reg_size = addrcells + sizecells;
-    int nr_cells = reg_size * mem->nr_banks;
+    int nr_cells = 0;
     /* Placeholder for memory@ + a 64-bit number + \0 */
     char buf[24];
     __be32 reg[NR_MEM_BANKS * 4 /* Worst case addrcells + sizecells */];
     __be32 *cells;
 
-    BUG_ON(nr_cells >= ARRAY_SIZE(reg));
     if ( mem->nr_banks == 0 )
         return -ENOENT;
 
-    dt_dprintk("Create memory node (reg size %d, nr cells %d)\n",
-               reg_size, nr_cells);
+    /* find first memory range not bound to a Xen domain */
+    for ( i = 0; i < mem->nr_banks && mem->bank[i].xen_domain; i++ )
+        ;
+    if ( i == mem->nr_banks )
+        return 0;
+
+    dt_dprintk("Create memory node\n");
 
     /* ePAPR 3.4 */
-    snprintf(buf, sizeof(buf), "memory@%"PRIx64, mem->bank[0].start);
+    snprintf(buf, sizeof(buf), "memory@%"PRIx64, mem->bank[i].start);
     res = fdt_begin_node(fdt, buf);
     if ( res )
         return res;
@@ -886,17 +890,24 @@ static int __init make_memory_node(const struct domain *d,
         return res;
 
     cells = &reg[0];
-    for ( i = 0 ; i < mem->nr_banks; i++ )
+    for ( ; i < mem->nr_banks; i++ )
     {
         u64 start = mem->bank[i].start;
         u64 size = mem->bank[i].size;
 
+        if ( mem->bank[i].xen_domain )
+            continue;
+
         dt_dprintk("  Bank %d: %#"PRIx64"->%#"PRIx64"\n",
                    i, start, start + size);
 
+        nr_cells += reg_size;
         dt_child_set_range(&cells, addrcells, sizecells, start, size);
     }
 
+    dt_dprintk("(reg size %d, nr cells %d)\n", reg_size, nr_cells);
+    BUG_ON(nr_cells >= ARRAY_SIZE(reg));
+
     res = fdt_property(fdt, "reg", reg, nr_cells * sizeof(*reg));
     if ( res )
         return res;
-- 
2.25.1