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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: Igor Mammedov <imammedo@redhat.com>
Message-Id: <1469623198-177227-1-git-send-email-imammedo@redhat.com>
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Igor Mammedov 2016-07-27 14:39:58 +02:00 committed by Paolo Bonzini
parent 0b646f44d9
commit 71ae65e552
1 changed files with 7 additions and 3 deletions
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10
hw/i2c/core.c
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@ -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);