Re: [Xen-devel] [PATCH] libxl: fix migrate for HVM guests

[Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>]

On Mon, 14 Feb 2011, Ian Campbell wrote:
> # HG changeset patch
> # User Ian Campbell <ian.campbell@xxxxxxxxxx>
> # Date 1297679825 0
> # Node ID 7648e0e731992c7d5d8b7e0d1c8615cc37a978e4
> # Parent  cfb1ab79e11d24ed3703b490a81d24c570cd2d91
> libxl: fix migrate for HVM guests
> 
> Prior to 22909:6868f7f3ab3f libxl would loop waiting simultaneously
> for the domain the acknowledge a PV suspend request (by clearing the
> XenStore node) and for the domain to actually suspend. For HVM guests
> without PV drivers this same loop was simply waiting for the domain to
> suspend.
> 
> In 22909:6868f7f3ab3f the original loop was split into two loops
> (first waiting for the acknowledgement and then for the actual
> suspend). This caused libxl to incorrectly wait for an HVM guest
> without PV drivers to acknowledge the XenStore request, which is not
> something it would ever do.
> 
> Fix this by only waiting for an acknowledgement from a guest which
> contains PV drivers.
> 
> Previously we were also making the request regardless of whether the
> guest had PV drivers, change that to only make the request if the
> guest has PV drivers.
> 
> Lastly there is no need to sample HVM_PARAM_ACPI_S_STATE twice and not
> doing so simplifies the test for PVHVM vs. normal HVM guests.
> 
> Tested with:
>       Windows with GPL PV drivers (event channel suspend mode)
>       Windows without PV drivers (xc_domain_shutdown mode)
>       Linux PV (PV with XenBus control node mode)
>       Linux HVM (PVHVM with XenBus control node mode (*))
>       Linux HVM (xc_domain_shutdown mode)
> 
> (*) In this case the kernel didn't actually suspend, due to:
>       PM: Device input1 failed to suspend: error -22
>       xen suspend: dpm_suspend_start -22
>     which may be a misconfiguration in my setup or may be a kernel
>     bug, but the libxl side dealt with this as gracefully as it could.
> 
> Signed-off-by: Ian Campbell <ian.campbell@xxxxxxxxxx>


Acked-by: Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>


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