Commit 71ae65e5 authored by Igor Mammedov's avatar Igor Mammedov Committed by Paolo Bonzini
Browse files

i2c: fix migration regression introduced by broadcast support 



QEMU fails migration with following error:

qemu-system-x86_64: Missing section footer for i2c_bus
qemu-system-x86_64: load of migration failed: Invalid argument

when migrating from:
  qemu-system-x86_64-v2.6.0 -m 256M rhel72.img -M pc-i440fx-2.6
to
  qemu-system-x86_64-v2.7.0-rc0 -m 256M rhel72.img -M pc-i440fx-2.6

Regression is added by commit 2293c27f (i2c: implement broadcast write)

Fix it by dropping 'broadcast' VMState introduced by 2293c27f and
reuse broadcast 0x00 address as broadcast flag in bus->saved_address.
Then if there were ongoing broadcast at migration time, set
bus->saved_address to it and at i2c_slave_post_load() time check
for it instead of transfering and using 'broadcast' VMState.

As result of reusing existing saved_address VMState, no compat
glue will be needed to keep forward/backward compatiblity. which
makes fix much less intrusive.

Signed-off-by: default avatarIgor Mammedov <imammedo@redhat.com>
Message-Id: <1469623198-177227-1-git-send-email-imammedo@redhat.com>
Reviewed-by: default avatarDr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent 0b646f44

hw/i2c/core.c

+7 −3
Original line number Diff line number Diff line
@@ -17,6 +17,8 @@ struct I2CNode { 
    QLIST_ENTRY(I2CNode) next;

};



#define I2C_BROADCAST 0x00



struct I2CBus

{

    BusState qbus;
@@ -47,6 +49,8 @@ static void i2c_bus_pre_save(void *opaque) 
    if (!QLIST_EMPTY(&bus->current_devs)) {

        if (!bus->broadcast) {

            bus->saved_address = QLIST_FIRST(&bus->current_devs)->elt->address;

        } else {

            bus->saved_address = I2C_BROADCAST;

        }

    }

}
@@ -58,7 +62,6 @@ static const VMStateDescription vmstate_i2c_bus = { 
    .pre_save = i2c_bus_pre_save,

    .fields = (VMStateField[]) {

        VMSTATE_UINT8(saved_address, I2CBus),

        VMSTATE_BOOL(broadcast, I2CBus),

        VMSTATE_END_OF_LIST()

    }

};
@@ -93,7 +96,7 @@ int i2c_start_transfer(I2CBus *bus, uint8_t address, int recv) 
    I2CSlaveClass *sc;

    I2CNode *node;



    if (address == 0x00) {

    if (address == I2C_BROADCAST) {

        /*

         * This is a broadcast, the current_devs will be all the devices of the

         * bus.
@@ -221,7 +224,8 @@ static int i2c_slave_post_load(void *opaque, int version_id) 
    I2CNode *node;



    bus = I2C_BUS(qdev_get_parent_bus(DEVICE(dev)));

    if ((bus->saved_address == dev->address) || (bus->broadcast)) {

    if ((bus->saved_address == dev->address) ||

        (bus->saved_address == I2C_BROADCAST)) {

        node = g_malloc(sizeof(struct I2CNode));

        node->elt = dev;

        QLIST_INSERT_HEAD(&bus->current_devs, node, next);