[PATCH] biosmem: Narrow or widen e820 memory regions as appropriate

[Damien Zammit]

This is needed because the e820 memory regions are not necessarily page aligned.
This fixes ACPICA probing of root table mapping.

TESTED with experimental acpi.

---
 i386/i386at/biosmem.c | 38 +++++++++++++++++++++++++++++++-------
 1 file changed, 31 insertions(+), 7 deletions(-)

diff --git a/i386/i386at/biosmem.c b/i386/i386at/biosmem.c
index 4f0914ca..779e542b 100644
--- a/i386/i386at/biosmem.c
+++ b/i386/i386at/biosmem.c
@@ -73,14 +73,22 @@ static unsigned int biosmem_nr_boot_data __bootdata;
 #define BIOSMEM_MAX_MAP_SIZE 128

 /*
- * Memory range types.
+ * Memory range types (as bitmask)
  */
-#define BIOSMEM_TYPE_AVAILABLE  1
-#define BIOSMEM_TYPE_RESERVED   2
-#define BIOSMEM_TYPE_ACPI       3
-#define BIOSMEM_TYPE_NVS        4
-#define BIOSMEM_TYPE_UNUSABLE   5
-#define BIOSMEM_TYPE_DISABLED   6
+#define BIOSMEM_TYPE_AVAILABLE  (1u << 0)
+#define BIOSMEM_TYPE_RESERVED   (1u << 1)
+#define BIOSMEM_TYPE_ACPI       (1u << 2)
+#define BIOSMEM_TYPE_NVS        (1u << 3)
+#define BIOSMEM_TYPE_UNUSABLE   (1u << 4)
+#define BIOSMEM_TYPE_DISABLED   (1u << 5)
+
+/*
+ * Bitmask corresponding to memory ranges that require narrowing
+ * to page boundaries. Unset ranges in the mask require widening.
+ */
+#define BIOSMEM_MASK_NARROW    ((BIOSMEM_TYPE_AVAILABLE | \
+                                 BIOSMEM_TYPE_NVS | \
+                                 BIOSMEM_TYPE_DISABLED))

 /*
  * Memory map entry.
@@ -248,6 +256,18 @@ biosmem_unregister_boot_data(phys_addr_t start, 
phys_addr_t end)

 #ifndef MACH_HYP

+static void __boot
+biosmem_map_adjust_alignment(struct biosmem_map_entry *e)
+{
+    if (e->type & BIOSMEM_MASK_NARROW) {
+        e->base_addr = vm_page_round (e->base_addr);
+        e->length = vm_page_trunc (e->length);
+    } else {
+        e->base_addr = vm_page_trunc (e->base_addr);
+        e->length = vm_page_round (e->length);
+    }
+}
+
 static void __boot
 biosmem_map_build(const struct multiboot_raw_info *mbi)
 {
@@ -268,6 +288,8 @@ biosmem_map_build(const struct multiboot_raw_info *mbi)
         entry->type = mb_entry->type;

         mb_entry = (void *)mb_entry + sizeof(mb_entry->size) + mb_entry->size;
+
+        biosmem_map_adjust_alignment(entry);
         entry++;
     }

@@ -283,11 +305,13 @@ biosmem_map_build_simple(const struct multiboot_raw_info 
*mbi)
     entry->base_addr = 0;
     entry->length = mbi->mem_lower << 10;
     entry->type = BIOSMEM_TYPE_AVAILABLE;
+    biosmem_map_adjust_alignment(entry);

     entry++;
     entry->base_addr = BIOSMEM_END;
     entry->length = mbi->mem_upper << 10;
     entry->type = BIOSMEM_TYPE_AVAILABLE;
+    biosmem_map_adjust_alignment(entry);

     biosmem_map_size = 2;
 }
--
2.34.1