[RFC,v2,19/44] hw/i386/e820: introduce a helper function to change type of e820

Commit Message

Isaku Yamahata July 8, 2021, 12:54 a.m. UTC

From: Isaku Yamahata <[e-mail]>

Introduce a helper function, e820_change_type(), that change
the type of subregion of e820 entry.
The following patch uses it.

Signed-off-by: Isaku Yamahata <[e-mail]>
---
 hw/i386/e820_memory_layout.c | 72 ++++++++++++++++++++++++++++++++++++
 hw/i386/e820_memory_layout.h |  1 +
 2 files changed, 73 insertions(+)

Comments

Gerd Hoffmann Aug. 26, 2021, 11:22 a.m. UTC | #1

On Wed, Jul 07, 2021 at 05:54:49PM -0700, [e-mail] wrote:
> From: Isaku Yamahata <[e-mail]>
> 
> Introduce a helper function, e820_change_type(), that change
> the type of subregion of e820 entry.

The entry is splited into multiple if needed.

> The following patch uses it.

Used to mark ram regions used for firmware as reserved.

More verbose commit messages please, it makes review easier if I don't
have to read the details out of the code changes.

thanks,
  Gerd

Patch

diff --git a/hw/i386/e820_memory_layout.c b/hw/i386/e820_memory_layout.c
index d9bb11c02a..109c4f715a 100644
--- a/hw/i386/e820_memory_layout.c
+++ b/hw/i386/e820_memory_layout.c
@@ -57,6 +57,78 @@  int e820_add_entry(uint64_t address, uint64_t length, uint32_t type)
     return e820_entries;
 }
 
+int e820_change_type(uint64_t address, uint64_t length, uint32_t type)
+{
+    size_t i;
+
+    if (type != E820_RAM) {
+        int ret = e820_append_reserve(address, length, type);
+        if (ret) {
+            return ret;
+        }
+    }
+
+    /* new "etc/e820" file -- include ram too */
+    for (i = 0; i < e820_entries; i++) {
+        struct e820_entry *e = &e820_table[i];
+        struct e820_entry tmp = {
+            .address = le64_to_cpu(e->address),
+            .length = le64_to_cpu(e->length),
+            .type = le32_to_cpu(e->type),
+        };
+        /* overlap? */
+        if (address + length < tmp.address ||
+            tmp.address + tmp.length < address) {
+            continue;
+        }
+        /*
+         * partial-overlap is not allowed.
+         * It is assumed that the region is completely contained within
+         * other region.
+         */
+        if (address < tmp.address ||
+            tmp.address + tmp.length < address + length) {
+            return -EINVAL;
+        }
+        /* only real type change is allowed. */
+        if (tmp.type == type) {
+            return -EINVAL;
+        }
+
+        if (tmp.address == address &&
+            tmp.address + tmp.length == address + length) {
+            e->type = cpu_to_le32(type);
+            return e820_entries;
+        } else if (tmp.address == address) {
+            e820_table = g_renew(struct e820_entry,
+                                 e820_table, e820_entries + 1);
+            e = &e820_table[i];
+            e->address = cpu_to_le64(tmp.address + length);
+            e820_append_entry(address, length, type);
+            return e820_entries;
+        } else if (tmp.address + tmp.length == address + length) {
+            e820_table = g_renew(struct e820_entry,
+                                 e820_table, e820_entries + 1);
+            e = &e820_table[i];
+            e->length = cpu_to_le64(tmp.length - length);
+            e820_append_entry(address, length, type);
+            return e820_entries;
+        } else {
+            e820_table = g_renew(struct e820_entry,
+                                 e820_table, e820_entries + 2);
+            e = &e820_table[i];
+            e->length = cpu_to_le64(address - tmp.address);
+            e820_append_entry(address, length, type);
+            e820_append_entry(address + length,
+                              tmp.address + tmp.length - (address + length),
+                              tmp.type);
+            return e820_entries;
+        }
+    }
+
+    return -EINVAL;
+}
+
 int e820_get_num_entries(void)
 {
     return e820_entries;
diff --git a/hw/i386/e820_memory_layout.h b/hw/i386/e820_memory_layout.h
index 2a0ceb8b9c..5f27cee476 100644
--- a/hw/i386/e820_memory_layout.h
+++ b/hw/i386/e820_memory_layout.h
@@ -33,6 +33,7 @@  extern struct e820_table e820_reserve;
 extern struct e820_entry *e820_table;
 
 int e820_add_entry(uint64_t address, uint64_t length, uint32_t type);
+int e820_change_type(uint64_t address, uint64_t length, uint32_t type);
 int e820_get_num_entries(void);
 bool e820_get_entry(int index, uint32_t type,
                     uint64_t *address, uint64_t *length);