[Qemu-devel] [RFC PATCH v1: 05/12] migration: support custom page loading

[mrhines]

From: "Michael R. Hines" <address@hidden>

Just as RDMA has custom routines for saving memory,
this provides us with custom routines for loading memory.

Micro-checkpointing needs this support in order to be able
to handle loading of the latest checkpoint into memory
as they are received from the network.

Signed-off-by: Michael R. Hines <address@hidden>
---
 arch_init.c                   | 17 ++++++++++++-----
 include/migration/migration.h | 12 ++++++++++--
 include/migration/qemu-file.h | 16 ++++++++++++++--
 savevm.c                      | 27 ++++++++++++++++++++++++---
 4 files changed, 60 insertions(+), 12 deletions(-)

diff --git a/arch_init.c b/arch_init.c
index b139512..9cf7d18 100644
--- a/arch_init.c
+++ b/arch_init.c
@@ -684,7 +684,7 @@ static int ram_save_block(QEMUFile *f, bool last_stage)
             /* In doubt sent page as normal */
             bytes_sent = -1;
             ret = ram_control_save_page(f, block->offset,
-                               offset, TARGET_PAGE_SIZE, &bytes_sent);
+                       block->host, offset, TARGET_PAGE_SIZE, &bytes_sent);
 
             if (ret != RAM_SAVE_CONTROL_NOT_SUPP) {
                 if (ret != RAM_SAVE_CONTROL_DELAYED) {
@@ -712,9 +712,11 @@ static int ram_save_block(QEMUFile *f, bool last_stage)
             /* XBZRLE overflow or normal page */
             if (bytes_sent == -1) {
                 bytes_sent = save_block_hdr(f, block, offset, cont, 
RAM_SAVE_FLAG_PAGE);
-                qemu_put_buffer_async(f, p, TARGET_PAGE_SIZE);
-                bytes_sent += TARGET_PAGE_SIZE;
-                acct_info.norm_pages++;
+                if (ret != RAM_SAVE_CONTROL_DELAYED) {
+                    qemu_put_buffer_async(f, p, TARGET_PAGE_SIZE);
+                    bytes_sent += TARGET_PAGE_SIZE;
+                    acct_info.norm_pages++;
+                }
             }
 
             /* if page is unmodified, continue to the next */
@@ -1133,13 +1135,18 @@ static int ram_load(QEMUFile *f, void *opaque, int 
version_id)
             ram_handle_compressed(host, ch, TARGET_PAGE_SIZE);
         } else if (flags & RAM_SAVE_FLAG_PAGE) {
             void *host;
+            int r;
 
             host = host_from_stream_offset(f, addr, flags);
             if (!host) {
                 return -EINVAL;
             }
 
-            qemu_get_buffer(f, host, TARGET_PAGE_SIZE);
+            r = ram_control_load_page(f, host, TARGET_PAGE_SIZE);
+
+            if (r == RAM_LOAD_CONTROL_NOT_SUPP) {
+                qemu_get_buffer(f, host, TARGET_PAGE_SIZE);
+            }
         } else if (flags & RAM_SAVE_FLAG_XBZRLE) {
             void *host = host_from_stream_offset(f, addr, flags);
             if (!host) {
diff --git a/include/migration/migration.h b/include/migration/migration.h
index 3ad06c5..ac1b438 100644
--- a/include/migration/migration.h
+++ b/include/migration/migration.h
@@ -169,9 +169,17 @@ void ram_control_load_hook(QEMUFile *f, uint64_t flags);
 
 #define RAM_SAVE_CONTROL_NOT_SUPP -1000
 #define RAM_SAVE_CONTROL_DELAYED  -2000
+#define RAM_LOAD_CONTROL_NOT_SUPP -3000
+#define RAM_LOAD_CONTROL_DELAYED  -4000
 
-size_t ram_control_save_page(QEMUFile *f, ram_addr_t block_offset,
-                             ram_addr_t offset, size_t size,
+#define RDMA_CONTROL_VERSION_CURRENT 1
+
+int ram_control_save_page(QEMUFile *f, ram_addr_t block_offset,
+                             uint8_t *host_addr,
+                             ram_addr_t offset, long size,
                              int *bytes_sent);
 
+int ram_control_load_page(QEMUFile *f,
+                             void *host_addr,
+                             long size);
 #endif
diff --git a/include/migration/qemu-file.h b/include/migration/qemu-file.h
index 0f757fb..d396b40 100644
--- a/include/migration/qemu-file.h
+++ b/include/migration/qemu-file.h
@@ -76,12 +76,22 @@ typedef int (QEMURamHookFunc)(QEMUFile *f, void *opaque, 
uint64_t flags);
  * This function allows override of where the RAM page
  * is saved (such as RDMA, for example.)
  */
-typedef size_t (QEMURamSaveFunc)(QEMUFile *f, void *opaque,
+typedef int (QEMURamSaveFunc)(QEMUFile *f, void *opaque,
                                ram_addr_t block_offset,
+                               uint8_t *host_addr,
                                ram_addr_t offset,
-                               size_t size,
+                               long size,
                                int *bytes_sent);
 
+/*
+ * This function allows override of where the RAM page
+ * is saved (such as RDMA, for example.)
+ */
+typedef int (QEMURamLoadFunc)(QEMUFile *f,
+                               void *opaque,
+                               void *host_addr,
+                               long size);
+
 typedef struct QEMUFileOps {
     QEMUFilePutBufferFunc *put_buffer;
     QEMUFileGetBufferFunc *get_buffer;
@@ -92,12 +102,14 @@ typedef struct QEMUFileOps {
     QEMURamHookFunc *after_ram_iterate;
     QEMURamHookFunc *hook_ram_load;
     QEMURamSaveFunc *save_page;
+    QEMURamLoadFunc *load_page;
 } QEMUFileOps;
 
 QEMUFile *qemu_fopen_ops(void *opaque, const QEMUFileOps *ops);
 QEMUFile *qemu_fopen(const char *filename, const char *mode);
 QEMUFile *qemu_fdopen(int fd, const char *mode);
 QEMUFile *qemu_fopen_socket(int fd, const char *mode);
+QEMUFile *qemu_fopen_mc(void *opaque, const char *mode);
 QEMUFile *qemu_popen_cmd(const char *command, const char *mode);
 int qemu_get_fd(QEMUFile *f);
 int qemu_fclose(QEMUFile *f);
diff --git a/savevm.c b/savevm.c
index 2f631d4..05f8a05 100644
--- a/savevm.c
+++ b/savevm.c
@@ -661,14 +661,17 @@ void ram_control_load_hook(QEMUFile *f, uint64_t flags)
     }
 }
 
-size_t ram_control_save_page(QEMUFile *f, ram_addr_t block_offset,
-                         ram_addr_t offset, size_t size, int *bytes_sent)
+int ram_control_save_page(QEMUFile *f, ram_addr_t block_offset,
+                         uint8_t *host_addr,
+                         ram_addr_t offset, long size, int *bytes_sent)
 {
     if (f->ops->save_page) {
         int ret = f->ops->save_page(f, f->opaque, block_offset,
+                                    host_addr,
                                     offset, size, bytes_sent);
 
-        if (ret != RAM_SAVE_CONTROL_DELAYED) {
+        if (ret != RAM_SAVE_CONTROL_DELAYED 
+                && ret != RAM_SAVE_CONTROL_NOT_SUPP) {
             if (bytes_sent && *bytes_sent > 0) {
                 qemu_update_position(f, *bytes_sent);
             } else if (ret < 0) {
@@ -682,6 +685,24 @@ size_t ram_control_save_page(QEMUFile *f, ram_addr_t 
block_offset,
     return RAM_SAVE_CONTROL_NOT_SUPP;
 }
 
+int ram_control_load_page(QEMUFile *f, void *host_addr, long size)
+{
+    if (f->ops->load_page) {
+        int ret = f->ops->load_page(f, f->opaque, host_addr, size);
+
+        if (ret != RAM_LOAD_CONTROL_DELAYED 
+                && ret != RAM_LOAD_CONTROL_NOT_SUPP) {
+            if (ret < 0) {
+                qemu_file_set_error(f, ret);
+            }
+        }
+
+        return ret;
+    }
+
+    return RAM_LOAD_CONTROL_NOT_SUPP;
+}
+
 static void qemu_fill_buffer(QEMUFile *f)
 {
     int len;
-- 
1.8.1.2