Re: [Xen-devel] [PATCH 1/2] xen/arm: remove workaround to inject evtchn_irq on irq enable

[Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>]

On Wed, 2 Jul 2014, Julien Grall wrote:
> On 07/02/2014 04:38 PM, Ian Campbell wrote:
> > On Wed, 2014-06-25 at 16:03 +0100, Julien Grall wrote:
> >> Hi Stefano,
> >>
> >> On 06/24/2014 07:11 PM, Stefano Stabellini wrote:
> >>> evtchn_upcall_pending is already set by common code at vcpu creation,
> >>> therefore on ARM we also need to call vgic_vcpu_inject_irq for it.
> >>> Currently we do that from vgic_enable_irqs as a workaround.
> >>>
> >>> Do this properly by calling vgic_vcpu_inject_irq in the appropriate
> >>> places at vcpu creation time, making sure to call it after the vcpu is
> >>> up (_VPF_down has been cleared).
> >>
> >> While it's works perfectly on common case, as the toolstack is always
> >> setting VGCF_online.
> >>
> >> It would be possible to call the hypercall DOMCTL_vcpusetcontext without
> >> this flags enable. If so, the new VCPU will never receive event channel
> >> interrupt.
> > 
> > I think the only other way to clear _VPF_down is the psci code, so I
> > suppose it needs a kick too.
> 
> The function PSCI on will call arch_set_info_guest directly with
> VGCF_online.
> 
> > The other option is VCPUOP_up whch we do not support (or wire up) on
> > ARM.
> 
> Hmmm... right I was looking directly to do_vcpu_op, but we have an extra
> layer on ARM (do_arm_vcpu_op).
> 
> In this case, I would return an error if VGCF_online is not set. I will
> allow us to catch easily an error later if we decide to implement VCPUOP_up.

I could print a message and return an error, seems reasonable.

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