arm/domain_build: Make find_unallocated_memory() more generic

At the moment, find_unallocated_memory() is only used to retrieve free
memory ranges for direct mapped domains in order to find extended
regions. It is not generic as it makes assumptions as for the place at
which it's being called (domain memory already allocated, gnttab region
already found) and hardcodes the memory banks to be excluded.

Make the function more generic, so that it can be used for other
purposes whenever there is a need to find free host memory regions (e.g.
upcoming LLC coloring series). Allow passing array with memory banks as a
parameter together with a callback to populate free regions structure,
as the logic may differ depending on the needs.

Add find_host_extended_regions() to be called from make_hypervisor_node()
to contain the logic to find extended regions for domains using host
memory layout that are not permitted to use IOMMU.

Signed-off-by: Michal Orzel <[email protected]>
Reviewed-by: Luca Fancellu <[email protected]>
Tested-by: Luca Fancellu <[email protected]>
Acked-by: Julien Grall <[email protected]>

xen/arch/arm/domain_build.c

@@ -901,31 +901,25 @@ int __init add_ext_regions(unsigned long s_gfn, unsigned long e_gfn,
 }
 
 /*
- * Find unused regions of Host address space which can be exposed to Dom0
- * as extended regions for the special memory mappings. In order to calculate
- * regions we exclude every region assigned to Dom0 from the Host RAM:
- * - domain RAM
- * - reserved-memory
- * - static shared memory
- * - grant table space
+ * Find unused regions of Host address space which can be exposed to domain
+ * using the host memory layout. In order to calculate regions we exclude every
+ * region passed in mem_banks from the Host RAM.
  */
 static int __init find_unallocated_memory(const struct kernel_info *kinfo,
-                                          struct membanks *ext_regions)
+                                          const struct membanks *mem_banks[],
+                                          unsigned int nr_mem_banks,
+                                          struct membanks *free_regions,
+                                          int (*cb)(unsigned long s_gfn,
+                                                    unsigned long e_gfn,
+                                                    void *data))
 {
     const struct membanks *mem = bootinfo_get_mem();
-    const struct membanks *mem_banks[] = {
-        kernel_info_get_mem_const(kinfo),
-        bootinfo_get_reserved_mem(),
-#ifdef CONFIG_STATIC_SHM
-        bootinfo_get_shmem(),
-#endif
-    };
     struct rangeset *unalloc_mem;
     paddr_t start, end;
     unsigned int i, j;
     int res;
 
-    dt_dprintk("Find unallocated memory for extended regions\n");
+    ASSERT(domain_use_host_layout(kinfo->d));
 
     unalloc_mem = rangeset_new(NULL, NULL, 0);
     if ( !unalloc_mem )
@@ -946,13 +940,8 @@ static int __init find_unallocated_memory(const struct kernel_info *kinfo,
         }
     }
 
-    /*
-     * Exclude the following regions:
-     * 1) Remove RAM assigned to Dom0
-     * 2) Remove reserved memory
-     * 3) Remove static shared memory (when the feature is enabled)
-     */
-    for ( i = 0; i < ARRAY_SIZE(mem_banks); i++ )
+    /* Remove all regions listed in mem_banks */
+    for ( i = 0; i < nr_mem_banks; i++ )
         for ( j = 0; j < mem_banks[i]->nr_banks; j++ )
         {
             start = mem_banks[i]->bank[j].start;
@@ -973,28 +962,13 @@ static int __init find_unallocated_memory(const struct kernel_info *kinfo,
             }
         }
 
-    /* Remove grant table region */
-    if ( kinfo->gnttab_size )
-    {
-        start = kinfo->gnttab_start;
-        end = kinfo->gnttab_start + kinfo->gnttab_size;
-        res = rangeset_remove_range(unalloc_mem, PFN_DOWN(start),
-                                    PFN_DOWN(end - 1));
-        if ( res )
-        {
-            printk(XENLOG_ERR "Failed to remove: %#"PRIpaddr"->%#"PRIpaddr"\n",
-                   start, end);
-            goto out;
-        }
-    }
-
     start = 0;
     end = (1ULL << p2m_ipa_bits) - 1;
     res = rangeset_report_ranges(unalloc_mem, PFN_DOWN(start), PFN_DOWN(end),
-                                 add_ext_regions, ext_regions);
+                                 cb, free_regions);
     if ( res )
-        ext_regions->nr_banks = 0;
-    else if ( !ext_regions->nr_banks )
+        free_regions->nr_banks = 0;
+    else if ( !free_regions->nr_banks )
         res = -ENOENT;
 
 out:
@@ -1170,6 +1144,44 @@ static int __init find_domU_holes(const struct kernel_info *kinfo,
     return remove_shm_holes_for_domU(kinfo, ext_regions);
 }
 
+static int __init find_host_extended_regions(const struct kernel_info *kinfo,
+                                             struct membanks *ext_regions)
+{
+    int res;
+    struct membanks *gnttab = xzalloc_flex_struct(struct membanks, bank, 1);
+
+    /*
+     * Exclude the following regions:
+     * 1) Remove RAM assigned to domain
+     * 2) Remove reserved memory
+     * 3) Grant table assigned to domain
+     * 4) Remove static shared memory (when the feature is enabled)
+     */
+    const struct membanks *mem_banks[] = {
+        kernel_info_get_mem_const(kinfo),
+        bootinfo_get_reserved_mem(),
+        gnttab,
+#ifdef CONFIG_STATIC_SHM
+        bootinfo_get_shmem(),
+#endif
+    };
+
+    dt_dprintk("Find unallocated memory for extended regions\n");
+
+    if ( !gnttab )
+        return -ENOMEM;
+
+    gnttab->nr_banks = 1;
+    gnttab->bank[0].start = kinfo->gnttab_start;
+    gnttab->bank[0].size = kinfo->gnttab_size;
+
+    res = find_unallocated_memory(kinfo, mem_banks, ARRAY_SIZE(mem_banks),
+                                  ext_regions, add_ext_regions);
+    xfree(gnttab);
+
+    return res;
+}
+
 int __init make_hypervisor_node(struct domain *d,
                                 const struct kernel_info *kinfo,
                                 int addrcells, int sizecells)
@@ -1226,7 +1238,7 @@ int __init make_hypervisor_node(struct domain *d,
         if ( is_domain_direct_mapped(d) )
         {
             if ( !is_iommu_enabled(d) )
-                res = find_unallocated_memory(kinfo, ext_regions);
+                res = find_host_extended_regions(kinfo, ext_regions);
             else
                 res = find_memory_holes(kinfo, ext_regions);
         }