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-rw-r--r--balloon.c11
-rw-r--r--hw/virtio/virtio-balloon.c4
-rw-r--r--include/sysemu/balloon.h2
-rw-r--r--migration/postcopy-ram.c9
4 files changed, 25 insertions, 1 deletions
diff --git a/balloon.c b/balloon.c
index 5d69e8a00b..0f45d1b5c4 100644
--- a/balloon.c
+++ b/balloon.c
@@ -36,6 +36,17 @@
 static QEMUBalloonEvent *balloon_event_fn;
 static QEMUBalloonStatus *balloon_stat_fn;
 static void *balloon_opaque;
+static bool balloon_inhibited;
+
+bool qemu_balloon_is_inhibited(void)
+{
+    return balloon_inhibited;
+}
+
+void qemu_balloon_inhibit(bool state)
+{
+    balloon_inhibited = state;
+}
 
 static bool have_balloon(Error **errp)
 {
diff --git a/hw/virtio/virtio-balloon.c b/hw/virtio/virtio-balloon.c
index c419b17143..9671635e63 100644
--- a/hw/virtio/virtio-balloon.c
+++ b/hw/virtio/virtio-balloon.c
@@ -37,9 +37,11 @@
 static void balloon_page(void *addr, int deflate)
 {
 #if defined(__linux__)
-    if (!kvm_enabled() || kvm_has_sync_mmu())
+    if (!qemu_balloon_is_inhibited() && (!kvm_enabled() ||
+                                         kvm_has_sync_mmu())) {
         qemu_madvise(addr, TARGET_PAGE_SIZE,
                 deflate ? QEMU_MADV_WILLNEED : QEMU_MADV_DONTNEED);
+    }
 #endif
 }
 
diff --git a/include/sysemu/balloon.h b/include/sysemu/balloon.h
index 17fe30070d..3f976b49e7 100644
--- a/include/sysemu/balloon.h
+++ b/include/sysemu/balloon.h
@@ -22,5 +22,7 @@ typedef void (QEMUBalloonStatus)(void *opaque, BalloonInfo *info);
 int qemu_add_balloon_handler(QEMUBalloonEvent *event_func,
 			     QEMUBalloonStatus *stat_func, void *opaque);
 void qemu_remove_balloon_handler(void *opaque);
+bool qemu_balloon_is_inhibited(void);
+void qemu_balloon_inhibit(bool state);
 
 #endif
diff --git a/migration/postcopy-ram.c b/migration/postcopy-ram.c
index 1a24b0937e..22d6b18e63 100644
--- a/migration/postcopy-ram.c
+++ b/migration/postcopy-ram.c
@@ -24,6 +24,7 @@
 #include "migration/migration.h"
 #include "migration/postcopy-ram.h"
 #include "sysemu/sysemu.h"
+#include "sysemu/balloon.h"
 #include "qemu/error-report.h"
 #include "trace.h"
 
@@ -308,6 +309,8 @@ int postcopy_ram_incoming_cleanup(MigrationIncomingState *mis)
         mis->have_fault_thread = false;
     }
 
+    qemu_balloon_inhibit(false);
+
     if (enable_mlock) {
         if (os_mlock() < 0) {
             error_report("mlock: %s", strerror(errno));
@@ -533,6 +536,12 @@ int postcopy_ram_enable_notify(MigrationIncomingState *mis)
         return -1;
     }
 
+    /*
+     * Ballooning can mark pages as absent while we're postcopying
+     * that would cause false userfaults.
+     */
+    qemu_balloon_inhibit(true);
+
     trace_postcopy_ram_enable_notify();
 
     return 0;