xen/hvm/params: Add a new delivery type for event-channel in HVM_PARAM_CALLBACK_IRQ

This new delivery type which is for ARM shares the same value with
HVM_PARAM_CALLBACK_TYPE_VECTOR which is for x86.

val[15:8] is flag: val[7:0] is a PPI.
To the flag, bit 8 stands the interrupt mode is edge(1) or level(0) and
bit 9 stands the interrupt polarity is active low(1) or high(0).

Signed-off-by: Shannon Zhao <[e-mail]>
Acked-by: Stefano Stabellini <[e-mail]>
Reviewed-by: Julien Grall <[e-mail]>
Tested-by: Julien Grall <[e-mail]>

include/xen/interface/hvm/params.h

···
  * Domain = val[47:32], Bus = val[31:16] DevFn = val[15:8], IntX = val[1:0]
  */
 
+#if defined(__i386__) || defined(__x86_64__)
 #define HVM_PARAM_CALLBACK_TYPE_VECTOR   2
 /*
  * val[7:0] is a vector number.  Check for XENFEAT_hvm_callback_vector to know
  * if this delivery method is available.
  */
+#elif defined(__arm__) || defined(__aarch64__)
+#define HVM_PARAM_CALLBACK_TYPE_PPI      2
+/*
+ * val[55:16] needs to be zero.
+ * val[15:8] is interrupt flag of the PPI used by event-channel:
+ *  bit 8: the PPI is edge(1) or level(0) triggered
+ *  bit 9: the PPI is active low(1) or high(0)
+ * val[7:0] is a PPI number used by event-channel.
+ * This is only used by ARM/ARM64 and masking/eoi the interrupt associated to
+ * the notification is handled by the interrupt controller.
+ */
+#endif
 
 #define HVM_PARAM_STORE_PFN    1
 #define HVM_PARAM_STORE_EVTCHN 2