[Qemu-devel] [PULL 2/2] migration/ram.c: do not set 'postcopy_running' in POSTCOPY_INCOMING_END
From: Daniel Henrique BarbozaWhen 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: 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 CC: Juan Quintela CC: Dr. David Alan Gilbert Reviewed-by: Peter Xu Reviewed-by: Juan Quintela Reported-by: Balamuruhan S Signed-off-by: Juan Quintela --- migration/ram.c | 16 ++-- 1 file changed, 14 insertions(+), 2 deletions(-) diff --git a/migration/ram.c b/migration/ram.c index 8620aa400a..021d583b9b 100644 --- a/migration/ram.c +++ b/migration/ram.c @@ -2798,6 +2798,18 @@ 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; @@ -2807,9 +2819,9 @@ 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++; -- 2.13.6
[Qemu-devel] [PULL 2/2] migration/ram.c: do not set 'postcopy_running' in POSTCOPY_INCOMING_END
From: Daniel Henrique BarbozaWhen 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: 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 a bit the semantics of postcopy_running inside ram_load, verifying first if we're not in the POSTCOPY_INCOMING_END state. In this case, postcopy_running is set to 'false'. Signed-off-by: Daniel Henrique Barboza Reviewed-by: Juan Quintela Signed-off-by: Juan Quintela --- migration/ram.c | 22 +++--- 1 file changed, 15 insertions(+), 7 deletions(-) diff --git a/migration/ram.c b/migration/ram.c index 8620aa400a..43ed719668 100644 --- a/migration/ram.c +++ b/migration/ram.c @@ -2803,13 +2803,21 @@ static int ram_load(QEMUFile *f, void *opaque, int version_id) int flags = 0, ret = 0, invalid_flags = 0; static uint64_t seq_iter; int len = 0; -/* - * If system is running in postcopy mode, page inserts to host memory must - * be atomic - */ -bool postcopy_running = postcopy_state_get() >= POSTCOPY_INCOMING_LISTENING; -/* ADVISE is earlier, it shows the source has the postcopy capability on */ -bool postcopy_advised = postcopy_state_get() >= POSTCOPY_INCOMING_ADVISE; +bool postcopy_advised = false, postcopy_running = false; +uint8_t postcopy_state = postcopy_state_get(); + +if (postcopy_state != POSTCOPY_INCOMING_END) { +/* + * If system is running in postcopy mode, page inserts to host memory + * must be atomic + */ +postcopy_running = postcopy_state >= POSTCOPY_INCOMING_LISTENING; + +/* ADVISE is earlier, it shows the source has the postcopy + * capability on + */ +postcopy_advised = postcopy_state >= POSTCOPY_INCOMING_ADVISE; +} seq_iter++; -- 2.13.6