1 files changed, 8 insertions, 2 deletions

diff --git a/include/xen/interface/physdev.h b/include/xen/interface/physdev.h
index 42721d13a106..610dba9b620a 100644
--- a/include/xen/interface/physdev.h
+++ b/include/xen/interface/physdev.h
@@ -131,6 +131,7 @@ struct physdev_irq {
 #define MAP_PIRQ_TYPE_GSI               0x1
 #define MAP_PIRQ_TYPE_UNKNOWN           0x2
 #define MAP_PIRQ_TYPE_MSI_SEG           0x3
+#define MAP_PIRQ_TYPE_MULTI_MSI         0x4
 
 #define PHYSDEVOP_map_pirq              13
 struct physdev_map_pirq {
@@ -141,11 +142,16 @@ struct physdev_map_pirq {
     int index;
     /* IN or OUT */
     int pirq;
-    /* IN - high 16 bits hold segment for MAP_PIRQ_TYPE_MSI_SEG */
+    /* IN - high 16 bits hold segment for ..._MSI_SEG and ..._MULTI_MSI */
     int bus;
     /* IN */
     int devfn;
-    /* IN */
+    /* IN
+     * - For MSI-X contains entry number.
+     * - For MSI with ..._MULTI_MSI contains number of vectors.
+     * OUT (..._MULTI_MSI only)
+     * - Number of vectors allocated.
+     */
     int entry_nr;
     /* IN */
     uint64_t table_base;