x86/xen: event channels delivery on HVM.
Set the callback to receive evtchns from Xen, using the
callback vector delivery mechanism.
The traditional way for receiving event channel notifications from Xen
is via the interrupts from the platform PCI device.
The callback vector is a newer alternative that allow us to receive
notifications on any vcpu and doesn't need any PCI support: we allocate
a vector exclusively to receive events, in the vector handler we don't
need to interact with the vlapic, therefore we avoid a VMEXIT.
Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
Signed-off-by: Sheng Yang <sheng@linux.intel.com>
Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
diff --git a/arch/x86/kernel/entry_32.S b/arch/x86/kernel/entry_32.S
index cd49141..6b19683 100644
--- a/arch/x86/kernel/entry_32.S
+++ b/arch/x86/kernel/entry_32.S
@@ -1166,6 +1166,9 @@
.previous
ENDPROC(xen_failsafe_callback)
+BUILD_INTERRUPT3(xen_hvm_callback_vector, XEN_HVM_EVTCHN_CALLBACK,
+ xen_evtchn_do_upcall)
+
#endif /* CONFIG_XEN */
#ifdef CONFIG_FUNCTION_TRACER