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pcie: drop version_id field for live migration 

While testing q35 live migration, I found that the migration would abort with
the following error: "Unknown savevm section type 76".

The error is due to this check failing in 'vmstate_load_state()':

    while(field->name) {
        if ((field->field_exists &&
             field->field_exists(opaque, version_id)) ||
            (!field->field_exists &&
             field->version_id <= version_id)) {

The VMSTATE_PCIE_DEVICE() currently has a 'version_id' set to 2. However,
'version_id' in the above check is 1. And thus we fail to load the pcie device
field. Further the code returns to 'qemu_loadvm_state()' which produces the
error that I saw.

I'm proposing to fix this by simply dropping the 'version_id' field from
VMSTATE_PCIE_DEVICE(). VMSTATE_PCI_DEVICE() defines no such field and further
the vmstate_pcie_device that VMSTATE_PCI_DEVICE() refers to is already
versioned. Thus, any versioning issues could be detected at the vmsd level.

Taking a step back, I think that the 'field->version_id' should be compared
against a saved version number for the field not the 'version_id'. Futhermore,
once vmstate_load_state() is called recursively on another vmsd, the check of:

    if (version_id > vmsd->version_id) {
        return -EINVAL;
    }

Will never fail since version_id is always equal to vmsd->version_id. So I'm
wondering why we aren't storing the vmsd version id of the source in the
migration stream?

This patch also renames the 'name' field of vmstate_pcie_device from:
PCIDevice -> PCIEDevice to differentiate it from vmstate_pci_device.

Signed-off-by: Jason Baron <jbaron@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
(cherry picked from commit 1de5345927)

Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>
This commit is contained in:
Jason Baron 2012-08-08 14:29:12 -04:00 committed by Michael Roth
parent 3aec24d195
commit 6ac46e3216
2 changed files with 1 additions and 2 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
hw/pci.c
View File

@ -439,7 +439,7 @@ const VMStateDescription vmstate_pci_device = {
};
const VMStateDescription vmstate_pcie_device = {
.name = "PCIDevice",
.name = "PCIEDevice",
.version_id = 2,
.minimum_version_id = 1,
.minimum_version_id_old = 1,

1
hw/pcie.h
View File

@ -133,7 +133,6 @@ extern const VMStateDescription vmstate_pcie_device;
#define VMSTATE_PCIE_DEVICE(_field, _state) { \
.name = (stringify(_field)), \
.version_id = 2, \
.size = sizeof(PCIDevice), \
.vmsd = &vmstate_pcie_device, \
.flags = VMS_STRUCT, \