From 50f063769cf74d2d37adbc5b568b545d2562af65 Mon Sep 17 00:00:00 2001

From: Laurent Vivier <lvivier@redhat.com>

Date: Tue, 28 Nov 2017 10:30:08 +0100

Subject: [PATCH 15/21] migration/ram.c: do not set 'postcopy_running' in

 POSTCOPY_INCOMING_END

RH-Author: Laurent Vivier <lvivier@redhat.com>

Message-id: <20171128103008.1150-1-lvivier@redhat.com>

Patchwork-id: 77931

O-Subject: [RHV7.5 qemu-kvm-rhev PATCH] migration/ram.c: do not set 'postcopy_running' in POSTCOPY_INCOMING_END

Bugzilla: 1516956

RH-Acked-by: Peter Xu <peterx@redhat.com>

RH-Acked-by: Dr. David Alan Gilbert <dgilbert@redhat.com>

RH-Acked-by: Juan Quintela <quintela@redhat.com>

RH-Acked-by: David Gibson <dgibson@redhat.com>

From: Daniel Henrique Barboza <danielhb@linux.vnet.ibm.com>

When migrating a VM with 'migrate_set_capability postcopy-ram on'

a postcopy_state is set during the process, ending up with the

state POSTCOPY_INCOMING_END when the migration is over. This

postcopy_state is taken into account inside ram_load to check

how it will load the memory pages. This same ram_load is called when

in a loadvm command.

Inside ram_load, the logic to see if we're at postcopy_running state

is:

postcopy_running = postcopy_state_get() >= POSTCOPY_INCOMING_LISTENING

postcopy_state_get() returns this enum type:

typedef enum {

    POSTCOPY_INCOMING_NONE = 0,

    POSTCOPY_INCOMING_ADVISE,

    POSTCOPY_INCOMING_DISCARD,

    POSTCOPY_INCOMING_LISTENING,

    POSTCOPY_INCOMING_RUNNING,

    POSTCOPY_INCOMING_END

} PostcopyState;

In the case where ram_load is executed and postcopy_state is

POSTCOPY_INCOMING_END, postcopy_running will be set to 'true' and

ram_load will behave like a postcopy is in progress. This scenario isn't

achievable in a migration but it is reproducible when executing

savevm/loadvm after migrating with 'postcopy-ram on', causing loadvm

to fail with Error -22:

Source:

(qemu) migrate_set_capability postcopy-ram on

(qemu) migrate tcp:127.0.0.1:4444

Dest:

(qemu) migrate_set_capability postcopy-ram on

(qemu)

ubuntu1704-intel login:

Ubuntu 17.04 ubuntu1704-intel ttyS0

ubuntu1704-intel login: (qemu)

(qemu) savevm test1

(qemu) loadvm test1

Unknown combination of migration flags: 0x4 (postcopy mode)

error while loading state for instance 0x0 of device 'ram'

Error -22 while loading VM state

(qemu)

This patch fixes this problem by changing the existing logic for

postcopy_advised and postcopy_running in ram_load, making them

'false' if we're at POSTCOPY_INCOMING_END state.

Signed-off-by: Daniel Henrique Barboza <danielhb@linux.vnet.ibm.com>

CC: Juan Quintela <quintela@redhat.com>

CC: Dr. David Alan Gilbert <dgilbert@redhat.com>

Reviewed-by: Peter Xu <peterx@redhat.com>

Reviewed-by: Juan Quintela <quintela@redhat.com>

Reported-by: Balamuruhan S <bala24@linux.vnet.ibm.com>

Signed-off-by: Juan Quintela <quintela@redhat.com>

(cherry picked from commit acab30b85db0885ab161aff4c83c550628f6d8ca)

Signed-off-by: Laurent Vivier <lvivier@redhat.com>

Signed-off-by: Miroslav Rezanina <mrezanin@redhat.com>

---

 migration/ram.c | 16 ++++++++++++++--

 1 file changed, 14 insertions(+), 2 deletions(-)

diff --git a/migration/ram.c b/migration/ram.c

index e18b3e2..fef80fd 100644

--- a/migration/ram.c

+++ b/migration/ram.c

@@ -2484,6 +2484,18 @@ static int ram_load_postcopy(QEMUFile *f)

     return ret;

 }

+static bool postcopy_is_advised(void)

+{

+    PostcopyState ps = postcopy_state_get();

+    return ps >= POSTCOPY_INCOMING_ADVISE && ps < POSTCOPY_INCOMING_END;

+}

+

+static bool postcopy_is_running(void)

+{

+    PostcopyState ps = postcopy_state_get();

+    return ps >= POSTCOPY_INCOMING_LISTENING && ps < POSTCOPY_INCOMING_END;

+}

+

 static int ram_load(QEMUFile *f, void *opaque, int version_id)

 {

     int flags = 0, ret = 0, invalid_flags = 0;

@@ -2493,9 +2505,9 @@ static int ram_load(QEMUFile *f, void *opaque, int version_id)

      * If system is running in postcopy mode, page inserts to host memory must

      * be atomic

      */

-    bool postcopy_running = postcopy_state_get() >= POSTCOPY_INCOMING_LISTENING;

+    bool postcopy_running = postcopy_is_running();

     /* ADVISE is earlier, it shows the source has the postcopy capability on */

-    bool postcopy_advised = postcopy_state_get() >= POSTCOPY_INCOMING_ADVISE;

+    bool postcopy_advised = postcopy_is_advised();

     seq_iter++;

-- 

1.8.3.1