xen/arm: Add memory overlap check for bootinfo.reserved_mem

As we are having more and more types of static region, and all of
these static regions are defined in bootinfo.reserved_mem, it is
necessary to add the overlap check of reserved memory regions in Xen,
because such check will help user to identify the misconfiguration in
the device tree at the early stage of boot time.

Currently we have 3 types of static region, namely
(1) static memory
(2) static heap
(3) static shared memory

(1) and (2) are parsed by the function `device_tree_get_meminfo()` and
(3) is parsed using its own logic. All of parsed information of these
types will be stored in `struct meminfo`.

Therefore, to unify the overlap checking logic for all of these types,
this commit firstly introduces a helper `meminfo_overlap_check()` and
a function `check_reserved_regions_overlap()` to check if an input
physical address range is overlapping with the existing memory regions
defined in bootinfo. After that, use `check_reserved_regions_overlap()`
in `device_tree_get_meminfo()` to do the overlap check of (1) and (2)
and replace the original overlap check of (3) with
`check_reserved_regions_overlap()`.

Signed-off-by: Henry Wang <Henry.Wang@arm.com>
Reviewed-by: Stefano Stabellini <sstabellini@kernel.org>

xen/arch/arm/bootfdt.c

@@ -88,6 +88,9 @@ static int __init device_tree_get_meminfo(const void *fdt, int node,
     for ( i = 0; i < banks && mem->nr_banks < NR_MEM_BANKS; i++ )
     {
         device_tree_get_reg(&cell, address_cells, size_cells, &start, &size);
+        if ( mem == &bootinfo.reserved_mem &&
+             check_reserved_regions_overlap(start, size) )
+            return -EINVAL;
         /* Some DT may describe empty bank, ignore them */
         if ( !size )
             continue;
@@ -482,7 +485,9 @@ static int __init process_shm_node(const void *fdt, int node,
                 return -EINVAL;
             }
 
-            if ( (end <= mem->bank[i].start) || (paddr >= bank_end) )
+            if ( check_reserved_regions_overlap(paddr, size) )
+                return -EINVAL;
+            else
             {
                 if ( strcmp(shm_id, mem->bank[i].shm_id) != 0 )
                     continue;
@@ -493,12 +498,6 @@ static int __init process_shm_node(const void *fdt, int node,
                     return -EINVAL;
                 }
             }
-            else
-            {
-                printk("fdt: shared memory region overlap with an existing entry %#"PRIpaddr" - %#"PRIpaddr"\n",
-                        mem->bank[i].start, bank_end);
-                return -EINVAL;
-            }
         }
     }
 

xen/arch/arm/include/asm/setup.h

@@ -143,6 +143,8 @@ void fw_unreserved_regions(paddr_t s, paddr_t e,
 size_t boot_fdt_info(const void *fdt, paddr_t paddr);
 const char *boot_fdt_cmdline(const void *fdt);
 
+bool check_reserved_regions_overlap(paddr_t region_start, paddr_t region_size);
+
 struct bootmodule *add_boot_module(bootmodule_kind kind,
                                    paddr_t start, paddr_t size, bool domU);
 struct bootmodule *boot_module_find_by_kind(bootmodule_kind kind);

xen/arch/arm/setup.c

@@ -261,6 +261,36 @@ static void __init dt_unreserved_regions(paddr_t s, paddr_t e,
     cb(s, e);
 }
 
+/*
+ * TODO: '*_end' could be 0 if the bank/region is at the end of the physical
+ * address space. This is for now not handled as it requires more rework.
+ */
+static bool __init meminfo_overlap_check(struct meminfo *meminfo,
+                                         paddr_t region_start,
+                                         paddr_t region_size)
+{
+    paddr_t bank_start = INVALID_PADDR, bank_end = 0;
+    paddr_t region_end = region_start + region_size;
+    unsigned int i, bank_num = meminfo->nr_banks;
+
+    for ( i = 0; i < bank_num; i++ )
+    {
+        bank_start = meminfo->bank[i].start;
+        bank_end = bank_start + meminfo->bank[i].size;
+
+        if ( region_end <= bank_start || region_start >= bank_end )
+            continue;
+        else
+        {
+            printk("Region: [%#"PRIpaddr", %#"PRIpaddr") overlapping with bank[%u]: [%#"PRIpaddr", %#"PRIpaddr")\n",
+                   region_start, region_end, i, bank_start, bank_end);
+            return true;
+        }
+    }
+
+    return false;
+}
+
 void __init fw_unreserved_regions(paddr_t s, paddr_t e,
                                   void (*cb)(paddr_t, paddr_t),
                                   unsigned int first)
@@ -271,7 +301,22 @@ void __init fw_unreserved_regions(paddr_t s, paddr_t e,
         cb(s, e);
 }
 
+/*
+ * Given an input physical address range, check if this range is overlapping
+ * with the existing reserved memory regions defined in bootinfo.
+ * Return true if the input physical address range is overlapping with any
+ * existing reserved memory regions, otherwise false.
+ */
+bool __init check_reserved_regions_overlap(paddr_t region_start,
+                                           paddr_t region_size)
+{
+    /* Check if input region is overlapping with bootinfo.reserved_mem banks */
+    if ( meminfo_overlap_check(&bootinfo.reserved_mem,
+                               region_start, region_size) )
+        return true;
 
+    return false;
+}
 
 struct bootmodule __init *add_boot_module(bootmodule_kind kind,
                                           paddr_t start, paddr_t size,