Re: [PATCH] xen/pvhvm: add soft reset on kexec/kdump support

[Boris Ostrovsky]

On 09/25/2015 09:59 AM, Konrad Rzeszutek Wilk wrote:
> On Fri, Sep 25, 2015 at 11:59:52AM +0200, Vitaly Kuznetsov wrote:
> > Currently there is a number of issues preventing PVHVM Xen guests from
> > doing successful kexec/kdump:
> > - Bound event channels.
> > - Registered vcpu_info.
> > - PIRQ/emuirq mappings.
> > - shared_info frame after XENMAPSPACE_shared_info operation.
> > - Active grant mappings.
> > Basically, newly booted kernel stumbles upon already set up Xen interfaces
> > and there is no way to reestablish them. In Xen-4.7 a new feature called
> > 'soft reset' is coming. A guest performing kexec/kdump operation is
> > supposed to call SCHEDOP_shutdown hypercall with SHUTDOWN_soft_reset reason
> > before jumping to new kernel. Hypervisor (with some help from toolstack)
> > will do full domain cleanup (but keeping its memory and vCPU contexts
> > intact) returning the guest to the state it had when it was first booted
> > and thus allowing it to start over.
> >
> > Doing SHUTDOWN_soft_reset on Xen hypervisors which don't support it is
> > probably OK as by default all unknown shutdown reasons cause domain destroy
> > with a message in toolstack log:
> > 'Unknown shutdown reason code 5. Destroying domain.'
> > which gives a clue to what the problem is and eliminates false
> > expectations.
> >
> > Signed-off-by: Vitaly Kuznetsov <vkuznets@xxxxxxxxxx>
> Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
>
> with s/pvhvm/hvm/
>
> to match with the rest of the file.
>
> Thanks.
> >   
> > +#ifdef CONFIG_KEXEC_CORE
> > +static void xen_pvhvm_kexec_shutdown(void)
> > +{
> > +	native_machine_shutdown();
> > +	if (kexec_in_progress)
> > +		xen_reboot(SHUTDOWN_soft_reset);
> > +}

This routine is not kexec-specific so "kexec_" should be dropped from 
the name.

Also, I am not sure I see how this new op will be used in the hypervisor 
--- currently AFAICS it is only processed under is_hardware_domain(). 
Are there other patches that will support HVM guests?


-boris

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