AMD/IOMMU: process softirqs while dumping IRTs

When there are sufficiently many devices listed in the ACPI tables (no
matter if they actually exist), output may take way longer than the
watchdog would like.

Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
---
v3: New.
---
TBD: Seeing the volume of output I wonder whether we should further
     suppress logging headers of devices which have no active entry
     (i.e. emit the header only upon finding the first IRTE worth
     logging). And while minor for the total volume of output I'm
     also unconvinced logging both a "per device" header line and a
     "shared" one makes sense, when only one of the two can actually
     be followed by actual contents.

--- a/xen/drivers/passthrough/amd/iommu_intr.c
+++ b/xen/drivers/passthrough/amd/iommu_intr.c
@@ -22,6 +22,7 @@
 #include <asm/hvm/svm/amd-iommu-proto.h>
 #include <asm/io_apic.h>
 #include <xen/keyhandler.h>
+#include <xen/softirq.h>
 
 struct irte_basic {
     bool remap_en:1;
@@ -917,6 +918,8 @@ static int dump_intremap_mapping(const s
     dump_intremap_table(iommu, ivrs_mapping->intremap_table);
     spin_unlock_irqrestore(&(ivrs_mapping->intremap_lock), flags);
 
+    process_pending_softirqs();
+
     return 0;
 }