RE: [Xen-devel] [PATCH 0/4] HVM Virtual S3

["Ian Pratt" <Ian.Pratt@xxxxxxxxxxxxx>]

> The main idea is:
> - emulate ACPI PM1A control resiger in QEMU to capture guest S3
request
> - when QEMU capture guest S3 request, it call hypercall to trap to Xen
> - Xen will suspend HVM by reseting all vcpus
> - on resume, "xm resume" will call hypercall to trap to Xen
> - Xen will resume HVM by setting HVM vcpu EIP to 0xfff0, cs base to
> 0xf0000,
>   and also set other related registers/msr to the correct
> value/attributes
>   in realmode environment which will start from rombios post Entry
code
>   in realmode directly when resuming.
> - rombios post code will start s3 resume by jumping to wakeup vector
> set
>   by guest OS.

Have you checked save/restore works when the guest is in S3 state? This
is essential for some of the server (as opposed to client) use cases for
guest S3.

[One thing to watch out for is that if the guest is in S3 it should be
possible to skip the usual synchronization with PV drivers as they will
already be shutdown.]


Further, do we actually need the s3 resume hypercall? Couldn't we just
put the VCPUs and xen-emulated devices into the right state for resume
at the end of s3 sleep and just leave the domain paused (i.e.
unscheduled)?


Also, do you have plans to implement an "xm send-power-event" type thing
that enables us to inform the guest of actions such as lid switch
open/close, power cable in/out, power button pressed etc ?

Many Thanks,
Ian




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