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/xen/xen-ops.h b/arch/x86/xen/xen-ops.h
index f9153a3..0d0e0e6 100644
--- a/arch/x86/xen/xen-ops.h
+++ b/arch/x86/xen/xen-ops.h
@@ -38,6 +38,8 @@
void xen_enable_syscall(void);
void xen_vcpu_restore(void);
+void xen_callback_vector(void);
+
void __init xen_build_dynamic_phys_to_machine(void);
void xen_init_irq_ops(void);