biosmem: Narrow e820 regions as required

Message-Id: <20220215064133.68593-1-damien@zamaudio.com>

1 files changed, 28 insertions, 0 deletions

diff --git a/i386/i386at/biosmem.c b/i386/i386at/biosmem.c
index 4f0914ca..78e7bb21 100644
--- a/i386/i386at/biosmem.c
+++ b/i386/i386at/biosmem.c
@@ -83,6 +83,19 @@ static unsigned int biosmem_nr_boot_data __bootdata;
 #define BIOSMEM_TYPE_DISABLED   6
 
 /*
+ * Bitmask corresponding to memory ranges that require narrowing
+ * to page boundaries.
+ */
+#define BIOSMEM_MASK_NARROW    (((1u << BIOSMEM_TYPE_AVAILABLE) | \
+                                 (1u << BIOSMEM_TYPE_NVS) | \
+                                 (1u << BIOSMEM_TYPE_DISABLED)))
+
+/*
+ * Helper macro to test if range type needs narrowing.
+ */
+#define BIOSMEM_NEEDS_NARROW(t)	((1u << t) & BIOSMEM_MASK_NARROW)
+
+/*
  * Memory map entry.
  */
 struct biosmem_map_entry {
@@ -249,6 +262,17 @@ 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)
+{
+    uint64_t end = e->base_addr + e->length;
+
+    if (BIOSMEM_NEEDS_NARROW(e->type)) {
+        e->base_addr = vm_page_round (e->base_addr);
+        e->length = vm_page_trunc (end) - e->base_addr;
+    }
+}
+
+static void __boot
 biosmem_map_build(const struct multiboot_raw_info *mbi)
 {
     struct multiboot_raw_mmap_entry *mb_entry, *mb_end;
@@ -268,6 +292,8 @@ 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 +309,13 @@ 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;
 }