Leaving the hooks untouched is at best a latent risk: There may well be
cases where some flush is needed, which then needs carrying out the
"register" way.

Switch from u<N> to uint<N>_t while needing to touch the function
headers anyway.

Signed-off-by: Jan Beulich <jbeulich@suse.com>

--- a/xen/drivers/passthrough/vtd/extern.h
+++ b/xen/drivers/passthrough/vtd/extern.h
@@ -49,6 +49,16 @@ int iommu_flush_iec_global(struct vtd_io
 int iommu_flush_iec_index(struct vtd_iommu *iommu, u8 im, u16 iidx);
 void clear_fault_bits(struct vtd_iommu *iommu);
 
+int __must_check vtd_flush_context_reg(struct vtd_iommu *iommu, uint16_t did,
+                                       uint16_t source_id,
+                                       uint8_t function_mask, uint64_t type,
+                                       bool flush_non_present_entry);
+int __must_check vtd_flush_iotlb_reg(struct vtd_iommu *iommu, uint16_t did,
+                                     uint64_t addr, unsigned int size_order,
+                                     uint64_t type,
+                                     bool flush_non_present_entry,
+                                     bool flush_dev_iotlb);
+
 struct vtd_iommu *ioapic_to_iommu(unsigned int apic_id);
 struct vtd_iommu *hpet_to_iommu(unsigned int hpet_id);
 struct acpi_drhd_unit *ioapic_to_drhd(unsigned int apic_id);
--- a/xen/drivers/passthrough/vtd/iommu.c
+++ b/xen/drivers/passthrough/vtd/iommu.c
@@ -380,10 +380,9 @@ static void iommu_flush_write_buffer(str
 }
 
 /* return value determine if we need a write buffer flush */
-static int __must_check flush_context_reg(struct vtd_iommu *iommu, u16 did,
-                                          u16 source_id, u8 function_mask,
-                                          u64 type,
-                                          bool flush_non_present_entry)
+int vtd_flush_context_reg(struct vtd_iommu *iommu, uint16_t did,
+                          uint16_t source_id, uint8_t function_mask,
+                          uint64_t type, bool flush_non_present_entry)
 {
     u64 val = 0;
     unsigned long flags;
@@ -449,11 +448,9 @@ static int __must_check iommu_flush_cont
 }
 
 /* return value determine if we need a write buffer flush */
-static int __must_check flush_iotlb_reg(struct vtd_iommu *iommu, u16 did,
-                                        u64 addr,
-                                        unsigned int size_order, u64 type,
-                                        bool flush_non_present_entry,
-                                        bool flush_dev_iotlb)
+int vtd_flush_iotlb_reg(struct vtd_iommu *iommu, uint16_t did, uint64_t addr,
+                        unsigned int size_order, uint64_t type,
+                        bool flush_non_present_entry, bool flush_dev_iotlb)
 {
     int tlb_offset = ecap_iotlb_offset(iommu->ecap);
     u64 val = 0;
@@ -2144,8 +2141,8 @@ static int __must_check init_vtd_hw(bool
          */
         if ( enable_qinval(iommu) != 0 )
         {
-            iommu->flush.context = flush_context_reg;
-            iommu->flush.iotlb   = flush_iotlb_reg;
+            iommu->flush.context = vtd_flush_context_reg;
+            iommu->flush.iotlb   = vtd_flush_iotlb_reg;
         }
     }
 
--- a/xen/drivers/passthrough/vtd/qinval.c
+++ b/xen/drivers/passthrough/vtd/qinval.c
@@ -462,4 +462,7 @@ void disable_qinval(struct vtd_iommu *io
                   !(sts & DMA_GSTS_QIES), sts);
 out:
     spin_unlock_irqrestore(&iommu->register_lock, flags);
+
+    iommu->flush.context = vtd_flush_context_reg;
+    iommu->flush.iotlb   = vtd_flush_iotlb_reg;
 }