[Qemu-devel] Windows balloon driver PFN issue

[Peter Xu]

Hi, Michael and the list,

I observed this on windows 8 enterprise guests, when doing memory ballooning:

address@hidden:virtio_balloon_to_target balloon target: 0x80000000 num_pages: 
524288
address@hidden:virtio_balloon_get_config num_pages: 524288 actual: 0
address@hidden:virtio_balloon_handle_output section name: pc.ram gpa: 
0x174604000
address@hidden:virtio_balloon_handle_output section name: pc.ram gpa: 0x0
address@hidden:virtio_balloon_handle_output section name: pc.ram gpa: 
0x17460a000
address@hidden:virtio_balloon_handle_output section name: pc.ram gpa: 0x0
address@hidden:virtio_balloon_handle_output section name: pc.ram gpa: 
0x17460b000
address@hidden:virtio_balloon_handle_output section name: pc.ram gpa: 0x0
address@hidden:virtio_balloon_handle_output section name: pc.ram gpa: 
0x17460c000
address@hidden:virtio_balloon_handle_output section name: pc.ram gpa: 0x0
address@hidden:virtio_balloon_handle_output section name: pc.ram gpa: 
0x17460d000
address@hidden:virtio_balloon_handle_output section name: pc.ram gpa: 0x0
address@hidden:virtio_balloon_handle_output section name: pc.ram gpa: 
0x17460e000
address@hidden:virtio_balloon_handle_output section name: pc.ram gpa: 0x0
address@hidden:virtio_balloon_handle_output section name: pc.ram gpa: 
0x17460f000
address@hidden:virtio_balloon_handle_output section name: pc.ram gpa: 0x0
...

I think it's very possible that these zero addresses (please let me
know what the first 4K page is used for if anyone knows, since IIUC
that's what we throw away now) are half of the 64bit PFN.  Or say, not
sure whether this means a windows guest driver bug that is using
64bits for PFN rather than 32bits (and I suppose the protocol is using
32bit for PFNs).

Michael, do you know what to do with this?

Thanks,

-- 
Peter Xu