Re: [Qemu-devel] [PATCH v4 7/7] hw/i386/pc_q35: advertise broadcast SMI if VCPU hotplug is turned off

[Eduardo Habkost]

On Thu, Dec 01, 2016 at 06:06:24PM +0100, Laszlo Ersek wrote:
> For the time being, we cannot handle SMIs in OVMF if VCPUs can show up
> after boot. Otherwise, advertise ICH9_LPC_SMI_F_BROADCAST.
> 
> Implement this generally, by introducing a new PCMachineClass method,
> namely get_smi_host_features(), and implement the above logic for
> pc-q35-2.9 and later. The idea is that future machine types might want to
> calculate (the same or different) SMI host features from different
> information, and that shouldn't affect earlier machine types.
> 
> In turn, validating guest feature requests (inter-feature dependencies)
> should be possible purely based on the available host feature set. For
> example, in the future we might enforce that the guest select
> ICH9_LPC_SMI_F_VCPU_PARKING as a prerequisite for
> ICH9_LPC_SMI_F_BROADCAST, but only if the machine type itself advertises
> ICH9_LPC_SMI_F_VCPU_PARKING.
> 
> Cc: "Michael S. Tsirkin" <address@hidden>
> Cc: Eduardo Habkost <address@hidden>
> Cc: Gerd Hoffmann <address@hidden>
> Cc: Igor Mammedov <address@hidden>
> Cc: Paolo Bonzini <address@hidden>
> Signed-off-by: Laszlo Ersek <address@hidden>
> ---
>  include/hw/i386/pc.h |  1 +
>  hw/i386/pc_q35.c     | 24 +++++++++++++++++++++++-
>  2 files changed, 24 insertions(+), 1 deletion(-)
> 
> diff --git a/include/hw/i386/pc.h b/include/hw/i386/pc.h
> index 430735e501dd..e164947116b6 100644
> --- a/include/hw/i386/pc.h
> +++ b/include/hw/i386/pc.h
> @@ -116,10 +116,11 @@ struct PCMachineClass {
>      /*< public >*/
>  
>      /* Methods: */
>      HotplugHandler *(*get_hotplug_handler)(MachineState *machine,
>                                             DeviceState *dev);
> +    uint64_t (*get_smi_host_features)(void);

I'd prefer to encode the differences between machine-types as
data, instead of code, to make introspection easier in the
future. Is it possible to encode this in a simple PCMachineClass
struct data field or (even bettter) a QOM property?

-- 
Eduardo