1 files changed, 35 insertions, 1 deletions
diff --git a/migration/migration.h b/migration/migration.h
index 8130b703eb..42c7395094 100644
--- a/migration/migration.h
+++ b/migration/migration.h
@@ -45,6 +45,24 @@ struct PostcopyBlocktimeContext;
  */
 #define CLEAR_BITMAP_SHIFT_MAX            31
 
+/* This is an abstraction of a "temp huge page" for postcopy's purpose */
+typedef struct {
+    /*
+     * This points to a temporary huge page as a buffer for UFFDIO_COPY.  It's
+     * mmap()ed and needs to be freed when cleanup.
+     */
+    void *tmp_huge_page;
+    /*
+     * This points to the host page we're going to install for this temp page.
+     * It tells us after we've received the whole page, where we should put it.
+     */
+    void *host_addr;
+    /* Number of small pages copied (in size of TARGET_PAGE_SIZE) */
+    unsigned int target_pages;
+    /* Whether this page contains all zeros */
+    bool all_zero;
+} PostcopyTmpPage;
+
 /* State for the incoming migration */
 struct MigrationIncomingState {
     QEMUFile *from_src_file;
@@ -81,7 +99,22 @@ struct MigrationIncomingState {
     QemuMutex rp_mutex;    /* We send replies from multiple threads */
     /* RAMBlock of last request sent to source */
     RAMBlock *last_rb;
-    void     *postcopy_tmp_page;
+    /*
+     * Number of postcopy channels including the default precopy channel, so
+     * vanilla postcopy will only contain one channel which contain both
+     * precopy and postcopy streams.
+     *
+     * This is calculated when the src requests to enable postcopy but before
+     * it starts.  Its value can depend on e.g. whether postcopy preemption is
+     * enabled.
+     */
+    unsigned int postcopy_channels;
+    /*
+     * An array of temp host huge pages to be used, one for each postcopy
+     * channel.
+     */
+    PostcopyTmpPage *postcopy_tmp_pages;
+    /* This is shared for all postcopy channels */
     void     *postcopy_tmp_zero_page;
     /* PostCopyFD's for external userfaultfds & handlers of shared memory */
     GArray   *postcopy_remote_fds;
@@ -391,5 +424,6 @@ bool migration_rate_limit(void);
 void migration_cancel(const Error *error);
 
 void populate_vfio_info(MigrationInfo *info);
+void postcopy_temp_page_reset(PostcopyTmpPage *tmp_page);
 
 #endif