Re: [Qemu-devel] [PATCH 1.1 0/4] Xen: Fix PV-on-HVM

[Michael S. Tsirkin]

On Tue, May 15, 2012 at 04:26:35PM +0100, Anthony PERARD wrote:
> In the context of PV-on-HVM under Xen, the emulated nics are supposed to be
> unplug before the guest drivers are initialized.

Guest drivers for which device?

> This mean that there must be unplug without the consent of the guest.
> Without this patch series, the guest end up with two nics with the
> same MAC, the emulated nic and the PV nic.

Shouldn't be a problem if one of them has link down state.
So maybe just be careful not to bring PV link up until after emulated
nic goes away?

> I tried few other path before to submite these patches:
>   - delayed the hot unplug in QEMU until the guest initialize the hotplug.
>     => the guest unplug the nic only after the driver initialized it. That's a
>       bit late.
>   - delayed the call to unplug the emulated device until pci_acpi_init is 
> called
>     => this is worse, the pv disc does not show up and the guest does not 
> boot.
> 
> In order to achive this fix, these patches introduce a new hotplug state only
> used in acpi_piix4, and a new qdev callback force_unplug.
> 
> Would it be possible to have this fix in the next release?
> 
> Thanks,
> 
> 
> Anthony PERARD (4):
>   Introduce a new hotplug state: Force eject.
>   qdev: Introduce qdev_force_unplug.
>   pci: Add force_unplug callback.
>   xen: Fix PV-on-HVM
> 
>  hw/acpi_piix4.c   |    5 +++++
>  hw/pci.c          |   15 +++++++++++++--
>  hw/pci.h          |    1 +
>  hw/qdev.c         |   23 ++++++++++++++++++++---
>  hw/qdev.h         |    3 +++
>  hw/xen_platform.c |    2 +-
>  6 files changed, 43 insertions(+), 6 deletions(-)
> 
> -- 
> Anthony PERARD