Re: [PATCH 1/5] xen: Fix event channel callback via INTX/GSI

[boris.ostrovsky@xxxxxxxxxx]

On 12/24/20 6:53 AM, David Woodhouse wrote:
> From: David Woodhouse <dwmw@xxxxxxxxxxxx>
>
> For a while, event channel notification via the PCI platform device
> has been broken, because we attempt to communicate with xenstore before
> we even have notifications working, with the xs_reset_watches() call
> in xs_init().
>
> We tend to get away with this on Xen versions below 4.0 because we avoid
> calling xs_reset_watches() anyway, because xenstore might not cope with
> reading a non-existent key. And newer Xen *does* have the vector
> callback support, so we rarely fall back to INTX/GSI delivery.
>
> To fix it, clean up a bit of the mess of xs_init() and xenbus_probe()
> startup. Call xs_init() directly from xenbus_init() only in the !XS_HVM
> case, deferring it to be called from xenbus_probe() in the XS_HVM case
> instead.
>
> Then fix up the invocation of xenbus_probe() to happen either from its
> device_initcall if the callback is available early enough, or when the
> callback is finally set up. This means that the hack of calling
> xenbus_probe() from a workqueue after the first interrupt, or directly
> from the PCI platform device setup, is no longer needed.
>
> Signed-off-by: David Woodhouse <dwmw@xxxxxxxxxxxx>


Reviewed-by: Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx>