xen/arm: introduce new helper parse_static_mem_prop and acquire_static_memory_bank

Later, we will introduce assign_static_memory_11 for allocating static
memory for direct-map domains, and it will share a lot common codes with
the existing allocate_static_memory.

In order not to bring a lot of duplicate codes, and also to make the whole
code more readable, this commit extracts common codes into two new helpers
parse_static_mem_prop and acquire_static_memory_bank.

Signed-off-by: Penny Zheng <penny.zheng@arm.com>
Reviewed-by: Stefano Stabellini <sstabellini@kernel.org>
Tested-by: Stefano Stabellini <sstabellini@kernel.org>

xen/arch/arm/domain_build.c

@@ -509,12 +509,69 @@ static bool __init append_static_memory_to_bank(struct domain *d,
     return true;
 }
 
+static mfn_t __init acquire_static_memory_bank(struct domain *d,
+                                               const __be32 **cell,
+                                               u32 addr_cells, u32 size_cells,
+                                               paddr_t *pbase, paddr_t *psize)
+{
+    mfn_t smfn;
+    int res;
+
+    device_tree_get_reg(cell, addr_cells, size_cells, pbase, psize);
+    ASSERT(IS_ALIGNED(*pbase, PAGE_SIZE) && IS_ALIGNED(*psize, PAGE_SIZE));
+    if ( PFN_DOWN(*psize) > UINT_MAX )
+    {
+        printk(XENLOG_ERR "%pd: static memory size too large: %#"PRIpaddr,
+               d, *psize);
+        return INVALID_MFN;
+    }
+
+    smfn = maddr_to_mfn(*pbase);
+    res = acquire_domstatic_pages(d, smfn, PFN_DOWN(*psize), 0);
+    if ( res )
+    {
+        printk(XENLOG_ERR
+               "%pd: failed to acquire static memory: %d.\n", d, res);
+        return INVALID_MFN;
+    }
+
+    return smfn;
+}
+
+static int __init parse_static_mem_prop(const struct dt_device_node *node,
+                                        u32 *addr_cells, u32 *size_cells,
+                                        int *length, const __be32 **cell)
+{
+    const struct dt_property *prop;
+
+    prop = dt_find_property(node, "xen,static-mem", NULL);
+    if ( !dt_property_read_u32(node, "#xen,static-mem-address-cells",
+                               addr_cells) )
+    {
+        printk(XENLOG_ERR
+               "failed to read \"#xen,static-mem-address-cells\".\n");
+        return -EINVAL;
+    }
+
+    if ( !dt_property_read_u32(node, "#xen,static-mem-size-cells",
+                               size_cells) )
+    {
+        printk(XENLOG_ERR
+               "failed to read \"#xen,static-mem-size-cells\".\n");
+        return -EINVAL;
+    }
+
+    *cell = (const __be32 *)prop->value;
+    *length = prop->length;
+
+    return 0;
+}
+
 /* Allocate memory from static memory as RAM for one specific domain d. */
 static void __init allocate_static_memory(struct domain *d,
                                           struct kernel_info *kinfo,
                                           const struct dt_device_node *node)
 {
-    const struct dt_property *prop;
     u32 addr_cells, size_cells, reg_cells;
     unsigned int nr_banks, gbank, bank = 0;
     const uint64_t rambase[] = GUEST_RAM_BANK_BASES;
@@ -523,24 +580,10 @@ static void __init allocate_static_memory(struct domain *d,
     u64 tot_size = 0;
     paddr_t pbase, psize, gsize;
     mfn_t smfn;
-    int res;
+    int length;
 
-    prop = dt_find_property(node, "xen,static-mem", NULL);
-    if ( !dt_property_read_u32(node, "#xen,static-mem-address-cells",
-                               &addr_cells) )
-    {
-        printk(XENLOG_ERR
-               "%pd: failed to read \"#xen,static-mem-address-cells\".\n", d);
+    if ( parse_static_mem_prop(node, &addr_cells, &size_cells, &length, &cell) )
         goto fail;
-    }
-
-    if ( !dt_property_read_u32(node, "#xen,static-mem-size-cells",
-                               &size_cells) )
-    {
-        printk(XENLOG_ERR
-               "%pd: failed to read \"#xen,static-mem-size-cells\".\n", d);
-        goto fail;
-    }
     reg_cells = addr_cells + size_cells;
 
     /*
@@ -551,29 +594,14 @@ static void __init allocate_static_memory(struct domain *d,
     gbank = 0;
     gsize = ramsize[gbank];
     kinfo->mem.bank[gbank].start = rambase[gbank];
-
-    cell = (const __be32 *)prop->value;
-    nr_banks = (prop->length) / (reg_cells * sizeof (u32));
+    nr_banks = length / (reg_cells * sizeof (u32));
 
     for ( ; bank < nr_banks; bank++ )
     {
-        device_tree_get_reg(&cell, addr_cells, size_cells, &pbase, &psize);
-        ASSERT(IS_ALIGNED(pbase, PAGE_SIZE) && IS_ALIGNED(psize, PAGE_SIZE));
-
-        if ( PFN_DOWN(psize) > UINT_MAX )
-        {
-            printk(XENLOG_ERR "%pd: static memory size too large: %#"PRIpaddr,
-                   d, psize);
+        smfn = acquire_static_memory_bank(d, &cell, addr_cells, size_cells,
+                                          &pbase, &psize);
+        if ( mfn_eq(smfn, INVALID_MFN) )
             goto fail;
-        }
-        smfn = maddr_to_mfn(pbase);
-        res = acquire_domstatic_pages(d, smfn, PFN_DOWN(psize), 0);
-        if ( res )
-        {
-            printk(XENLOG_ERR
-                   "%pd: failed to acquire static memory: %d.\n", d, res);
-            goto fail;
-        }
 
         printk(XENLOG_INFO "%pd: STATIC BANK[%u] %#"PRIpaddr"-%#"PRIpaddr"\n",
                d, bank, pbase, pbase + psize);