Re: [RFC PATCH v1 22/25] hw/xen: Add emulated implementation of XenStore operations

[Paul Durrant <xadimgnik@xxxxxxxxx>]

On 02/03/2023 15:34, David Woodhouse wrote:
> From: David Woodhouse <dwmw@xxxxxxxxxxxx>
>
> Now that we have an internal implementation of XenStore, we can populate
> the xenstore_backend_ops to allow PV backends to talk to it.
>
> Watches can't be processed with immediate callbacks because that would
> call back into XenBus code recursively. Defer them to a QEMUBH to be run
> as appropriate from the main loop. We use a QEMUBH per XS handle, and it
> walks all the watches (there shouldn't be many per handle) to fire any
> which have pending events. We *could* have done it differently but this
> allows us to use the same struct watch_event as we have for the guest
> side, and keeps things relatively simple.
Yes, it's more consistent with watch events on real Xen this way.

> Signed-off-by: David Woodhouse <dwmw@xxxxxxxxxxxx>
> ---
>   hw/i386/kvm/xen_xenstore.c | 273 ++++++++++++++++++++++++++++++++++++-
>   1 file changed, 269 insertions(+), 4 deletions(-)
Reviewed-by: Paul Durrant <paul@xxxxxxx>