qemu-xen: if pirq == 0 fall back to emulated MSIs

If the pirq requested is 0, it probably means that the guest is
misconfigured, so fall back to the emulated code path.

This patch depends on "qemu-xen: support PV on HVM MSIX remapping".

Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>

diff --git a/hw/pt-msi.c b/hw/pt-msi.c
index b01744ed520d32dbc53dee9d37674eed24f0bd08..71fa6f00414566bdbd0d0c0cff6fa853275b485e 100644 (file)
--- a/hw/pt-msi.c
+++ b/hw/pt-msi.c
@@ -79,7 +79,12 @@ int pt_msi_setup(struct pt_dev *dev)
          * is passed as dest_id */
         pirq = (dev->msi->addr_hi & 0xffffff00) |
                ((dev->msi->addr_lo >> MSI_TARGET_CPU_SHIFT) & 0xff);
-        PT_LOG("pt_msi_setup requested pirq = %d\n", pirq);
+        if (!pirq)
+            /* this probably identifies an misconfiguration of the guest,
+             * try the emulated path */
+            pirq = -1;
+        else
+            PT_LOG("pt_msi_setup requested pirq = %d\n", pirq);
     }
 
     if ( xc_physdev_map_pirq_msi(xc_handle, domid, AUTO_ASSIGN, &pirq,
@@ -305,7 +310,12 @@ static int pt_msix_update_one(struct pt_dev *dev, int entry_nr)
          * is passed as dest_id */
         pirq = ((gaddr >> 32) & 0xffffff00) |
                (((gaddr & 0xffffffff) >> MSI_TARGET_CPU_SHIFT) & 0xff);
-        PT_LOG("pt_msix_update_one requested pirq = %d\n", pirq);
+        if (!pirq)
+            /* this probably identifies an misconfiguration of the guest,
+             * try the emulated path */
+            pirq = -1;
+        else
+            PT_LOG("pt_msix_update_one requested pirq = %d\n", pirq);
     }
 
     /* Check if this entry is already mapped */