x68: acpi: trigger SMI before sending hotplug Notify event to OSPM

x68: acpi: trigger SMI before sending hotplug Notify event to OSPM

In case firmware has negotiated CPU hotplug SMI feature, generate
AML to describe SMI IO port region and send SMI to firmware
on each CPU hotplug SCI in case new CPUs were hotplugged.

Since new CPUs can be hotplugged while CPU_SCAN_METHOD is running
we can't send SMI before new CPUs are fetched from QEMU as it
could cause sending Notify to a CPU that firmware hasn't seen yet.
So fetch new CPUs into local cache first, then send SMI and
after that send Notify events to cached CPUs. This should ensure
that Notify is sent only to CPUs which were processed by firmware
first.
Any CPUs that were hotplugged after caching will be processed
by the next CPU_SCAN_METHOD, when pending SCI is handled.

Signed-off-by: Igor Mammedov <imammedo@redhat.com>
Reviewed-by: Laszlo Ersek <lersek@redhat.com>
Tested-by: Laszlo Ersek <lersek@redhat.com>
Message-Id: <20200923094650.1301166-10-imammedo@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>