[PATCH v3 1/2] xen/arm: exclude xen,reg from direct-map domU extended regions

[Stewart Hildebrand <stewart.hildebrand@xxxxxxx>]

Similarly to fba1b0974dd8, when a device is passed through to a
direct-map dom0less domU, the xen,reg ranges may overlap with the
extended regions. Remove xen,reg from direct-map domU extended regions.

Introduce rangeset_count_ranges().

Take the opportunity to update the comment ahead of find_memory_holes().

Signed-off-by: Stewart Hildebrand <stewart.hildebrand@xxxxxxx>
---
v2->v3:
* new patch
---
 xen/arch/arm/domain_build.c | 57 +++++++++++++++++++++++++++++++++----
 xen/common/rangeset.c       | 14 +++++++++
 xen/include/xen/rangeset.h  |  2 ++
 3 files changed, 68 insertions(+), 5 deletions(-)

diff --git a/xen/arch/arm/domain_build.c b/xen/arch/arm/domain_build.c
index b189a7cfae9f..3cdf5839bc98 100644
--- a/xen/arch/arm/domain_build.c
+++ b/xen/arch/arm/domain_build.c
@@ -824,15 +824,17 @@ static int __init handle_pci_range(const struct 
dt_device_node *dev,
 }
 
 /*
- * Find the holes in the Host DT which can be exposed to Dom0 as extended
- * regions for the special memory mappings. In order to calculate regions
- * we exclude every addressable memory region described by "reg" and "ranges"
- * properties from the maximum possible addressable physical memory range:
+ * Find the holes in the Host DT which can be exposed to Dom0 or a direct-map
+ * domU as extended regions for the special memory mappings. In order to
+ * calculate regions we exclude every addressable memory region described by
+ * "reg" and "ranges" properties from the maximum possible addressable physical
+ * memory range:
  * - MMIO
  * - Host RAM
  * - PCI aperture
  * - Static shared memory regions, which are described by special property
  *   "xen,shared-mem"
+ * - xen,reg mappings
  */
 static int __init find_memory_holes(const struct kernel_info *kinfo,
                                     struct membanks *ext_regions)
@@ -914,6 +916,13 @@ static int __init find_memory_holes(const struct 
kernel_info *kinfo,
         }
     }
 
+    if ( kinfo->xen_reg_assigned )
+    {
+        res = rangeset_subtract(mem_holes, kinfo->xen_reg_assigned);
+        if ( res )
+            goto out;
+    }
+
     start = 0;
     end = (1ULL << p2m_ipa_bits) - 1;
     res = rangeset_report_ranges(mem_holes, PFN_DOWN(start), PFN_DOWN(end),
@@ -994,11 +1003,30 @@ static int __init find_domU_holes(const struct 
kernel_info *kinfo,
     return res;
 }
 
+static int __init rangeset_to_membank(unsigned long s_gfn, unsigned long e_gfn,
+                                      void *data)
+{
+    struct membanks *membank = data;
+    paddr_t s = pfn_to_paddr(s_gfn);
+    paddr_t e = pfn_to_paddr(e_gfn + 1) - 1;
+
+    if ( membank->nr_banks >= membank->max_banks )
+        return 0;
+
+    membank->bank[membank->nr_banks].start = s;
+    membank->bank[membank->nr_banks].size = e - s + 1;
+    membank->nr_banks++;
+
+    return 0;
+}
+
 static int __init find_host_extended_regions(const struct kernel_info *kinfo,
                                              struct membanks *ext_regions)
 {
     int res;
     struct membanks *gnttab = membanks_xzalloc(1, MEMORY);
+    struct membanks *xen_reg = membanks_xzalloc(
+        max(1, rangeset_count_ranges(kinfo->xen_reg_assigned)), MEMORY);
 
     /*
      * Exclude the following regions:
@@ -1006,6 +1034,7 @@ static int __init find_host_extended_regions(const struct 
kernel_info *kinfo,
      * 2) Remove reserved memory
      * 3) Grant table assigned to domain
      * 4) Remove static shared memory (when the feature is enabled)
+     * 5) Remove xen,reg
      */
     const struct membanks *mem_banks[] = {
         kernel_info_get_mem_const(kinfo),
@@ -1014,12 +1043,27 @@ static int __init find_host_extended_regions(const 
struct kernel_info *kinfo,
 #ifdef CONFIG_STATIC_SHM
         bootinfo_get_shmem(),
 #endif
+        xen_reg,
     };
 
     dt_dprintk("Find unallocated memory for extended regions\n");
 
     if ( !gnttab )
-        return -ENOMEM;
+    {
+        res = -ENOMEM;
+        goto out;
+    }
+
+    if ( !xen_reg )
+    {
+        res = -ENOMEM;
+        goto out;
+    }
+
+    if ( kinfo->xen_reg_assigned )
+        rangeset_report_ranges(kinfo->xen_reg_assigned, 0,
+                               PFN_DOWN((1ULL << p2m_ipa_bits) - 1),
+                               rangeset_to_membank, xen_reg);
 
     gnttab->nr_banks = 1;
     gnttab->bank[0].start = kinfo->gnttab_start;
@@ -1027,6 +1071,9 @@ static int __init find_host_extended_regions(const struct 
kernel_info *kinfo,
 
     res = find_unallocated_memory(kinfo, mem_banks, ARRAY_SIZE(mem_banks),
                                   ext_regions, add_ext_regions);
+
+ out:
+    xfree(xen_reg);
     xfree(gnttab);
 
     return res;
diff --git a/xen/common/rangeset.c b/xen/common/rangeset.c
index b9e8912fb1c3..77b37ad9b196 100644
--- a/xen/common/rangeset.c
+++ b/xen/common/rangeset.c
@@ -433,6 +433,20 @@ bool rangeset_is_empty(
     return ((r == NULL) || list_empty(&r->range_list));
 }
 
+int rangeset_count_ranges(const struct rangeset *r)
+{
+    int nr = 0;
+    struct list_head *list;
+
+    if ( r == NULL )
+        return 0;
+
+    list_for_each( list, &r->range_list )
+        nr++;
+
+    return nr;
+}
+
 struct rangeset *rangeset_new(
     struct domain *d, const char *name, unsigned int flags)
 {
diff --git a/xen/include/xen/rangeset.h b/xen/include/xen/rangeset.h
index 817505badf6f..96cc0b5d7930 100644
--- a/xen/include/xen/rangeset.h
+++ b/xen/include/xen/rangeset.h
@@ -56,6 +56,8 @@ void rangeset_limit(
 bool __must_check rangeset_is_empty(
     const struct rangeset *r);
 
+int __must_check rangeset_count_ranges(const struct rangeset *r);
+
 /* Add/claim/remove/query/purge a numeric range. */
 int __must_check rangeset_add_range(
     struct rangeset *r, unsigned long s, unsigned long e);
-- 
2.49.0