[Qemu-devel] [PATCH RESEND V3 4/6] migration: add postcopy downtime into MigrationIncommingState

[Alexey Perevalov <a.perevalov@samsung.com>]

This patch add request to kernel space for UFFD_FEATURE_THREAD_ID,
in case when this feature is provided by kernel.

DowntimeContext is incapsulated inside migration.c.

Signed-off-by: Alexey Perevalov <a.perevalov@samsung.com>
---
 include/migration/migration.h | 12 ++++++++++++
 migration/migration.c         | 33 +++++++++++++++++++++++++++++++++
 migration/postcopy-ram.c      |  8 ++++++++
 3 files changed, 53 insertions(+)

diff --git a/include/migration/migration.h b/include/migration/migration.h
index ba1a16c..e8fb68f 100644
--- a/include/migration/migration.h
+++ b/include/migration/migration.h
@@ -83,6 +83,8 @@ typedef enum {
     POSTCOPY_INCOMING_END
 } PostcopyState;
 
+struct DowntimeContext;
+
 /* State for the incoming migration */
 struct MigrationIncomingState {
     QEMUFile *from_src_file;
@@ -123,10 +125,20 @@ struct MigrationIncomingState {
 
     /* See savevm.c */
     LoadStateEntry_Head loadvm_handlers;
+
+    /*
+     * DowntimeContext to keep information for postcopy
+     * live migration, to calculate downtime
+     * */
+    struct DowntimeContext *downtime_ctx;
 };
 
 MigrationIncomingState *migration_incoming_get_current(void);
 void migration_incoming_state_destroy(void);
+/*
+ * Functions to work with downtime context
+ */
+struct DowntimeContext *downtime_context_new(void);
 
 struct MigrationState
 {
diff --git a/migration/migration.c b/migration/migration.c
index 569a7f6..ec76e5c 100644
--- a/migration/migration.c
+++ b/migration/migration.c
@@ -77,6 +77,18 @@ static NotifierList migration_state_notifiers =
 
 static bool deferred_incoming;
 
+typedef struct DowntimeContext {
+    /* time when page fault initiated per vCPU */
+    int64_t *page_fault_vcpu_time;
+    /* page address per vCPU */
+    uint64_t *vcpu_addr;
+    int64_t total_downtime;
+    /* downtime per vCPU */
+    int64_t *vcpu_downtime;
+    /* point in time when last page fault was initiated */
+    int64_t last_begin;
+} DowntimeContext;
+
 /*
  * Current state of incoming postcopy; note this is not part of
  * MigrationIncomingState since it's state is used during cleanup
@@ -116,6 +128,23 @@ MigrationState *migrate_get_current(void)
     return &current_migration;
 }
 
+struct DowntimeContext *downtime_context_new(void)
+{
+    DowntimeContext *ctx = g_new0(DowntimeContext, 1);
+    ctx->page_fault_vcpu_time = g_new0(int64_t, smp_cpus);
+    ctx->vcpu_addr = g_new0(uint64_t, smp_cpus);
+    ctx->vcpu_downtime = g_new0(int64_t, smp_cpus);
+    return ctx;
+}
+
+static void destroy_downtime_context(struct DowntimeContext *ctx)
+{
+    g_free(ctx->page_fault_vcpu_time);
+    g_free(ctx->vcpu_addr);
+    g_free(ctx->vcpu_downtime);
+    g_free(ctx);
+}
+
 MigrationIncomingState *migration_incoming_get_current(void)
 {
     static bool once;
@@ -138,6 +167,10 @@ void migration_incoming_state_destroy(void)
 
     qemu_event_destroy(&mis->main_thread_load_event);
     loadvm_free_handlers(mis);
+    if (mis->downtime_ctx) {
+        destroy_downtime_context(mis->downtime_ctx);
+        mis->downtime_ctx = NULL;
+    }
 }
 
 
diff --git a/migration/postcopy-ram.c b/migration/postcopy-ram.c
index 21e7150..f3688f5 100644
--- a/migration/postcopy-ram.c
+++ b/migration/postcopy-ram.c
@@ -132,6 +132,14 @@ static bool ufd_version_check(int ufd, MigrationIncomingState *mis)
         return false;
     }
 
+#ifdef UFFD_FEATURE_THREAD_ID
+    if (mis && UFFD_FEATURE_THREAD_ID & supported_features) {
+        /* kernel supports that feature */
+        mis->downtime_ctx = downtime_context_new();
+        new_features |= UFFD_FEATURE_THREAD_ID;
+    }
+#endif
+
     /* request features */
     if (new_features && !request_ufd_features(ufd, new_features)) {
         error_report("ufd_version_check failed: features %" PRIu64,
-- 
1.9.1