Re: [Qemu-devel] [PATCH v4] virtio-blk: set correct config size for the host driver

[Stefan Hajnoczi <stefanha@gmail.com>]

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On Tue, Feb 12, 2019 at 09:05:11PM -0500, Michael S. Tsirkin wrote:
> On Wed, Feb 13, 2019 at 09:48:57AM +0800, Changpeng Liu wrote:
> > Commit caa1ee43 "vhost-user-blk: add discard/write zeroes features
> > support" added fields to struct virtio_blk_config. This changes
> > the size of the config space and breaks migration from QEMU 3.1
> > and older:
> > 
> > qemu-system-ppc64: get_pci_config_device: Bad config data: i=0x10 read: 41 device: 1 cmask: ff wmask: 80 w1cmask:0
> > qemu-system-ppc64: Failed to load PCIDevice:config
> > qemu-system-ppc64: Failed to load virtio-blk:virtio
> > qemu-system-ppc64: error while loading state for instance 0x0 of device 'pci@800000020000000:01.0/virtio-blk'
> > qemu-system-ppc64: load of migration failed: Invalid argument
> > 
> > Since virtio-blk doesn't support the "discard" and "write zeroes"
> > features, it shouldn't even expose the associated fields in the
> > config space actually. Just include all fields up to num_queues to
> > match QEMU 3.1 and older.
> > 
> > Signed-off-by: Changpeng Liu <changpeng.liu@intel.com>
> 
> 
> Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
> 
> Stefan, are you merging this?

Yes.

Stefan

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