xen/pci: solve compilation error on ARM with HAS_PCI enabled

If mem-sharing, mem-paging, or log-dirty functionality is not enabled
for architecture when HAS_PCI is enabled, the compiler will throw an
error.

Move code to x86 specific file to fix compilation error.

Also, modify the code to use likely() in place of unlikley() for each
condition to make code more optimized.

No functional change intended.
Signed-off-by: Rahul Singh <rahul.singh@arm.com>
Reviewed-by: Bertrand Marquis <bertrand.marquis@arm.com>
Acked-by: Jan Beulich <jbeulich@suse.com>

xen/drivers/passthrough/pci.c

@@ -23,7 +23,6 @@
 #include <xen/iommu.h>
 #include <xen/irq.h>
 #include <xen/param.h>
-#include <xen/vm_event.h>
 #include <xen/delay.h>
 #include <xen/keyhandler.h>
 #include <xen/event.h>
@@ -1421,12 +1420,7 @@ static int assign_device(struct domain *d, u16 seg, u8 bus, u8 devfn, u32 flag)
     if ( !is_iommu_enabled(d) )
         return 0;
 
-    /* Prevent device assign if mem paging or mem sharing have been 
-     * enabled for this domain */
-    if ( d != dom_io &&
-         unlikely(mem_sharing_enabled(d) ||
-                  vm_event_check_ring(d->vm_event_paging) ||
-                  p2m_get_hostp2m(d)->global_logdirty) )
+    if ( !arch_iommu_use_permitted(d) )
         return -EXDEV;
 
     /* device_assigned() should already have cleared the device for assignment */

xen/drivers/passthrough/x86/iommu.c

@@ -18,6 +18,7 @@
 #include <xen/guest_access.h>
 #include <xen/event.h>
 #include <xen/softirq.h>
+#include <xen/vm_event.h>
 #include <xsm/xsm.h>
 
 #include <asm/hvm/io.h>
@@ -308,6 +309,18 @@ struct page_info *iommu_alloc_pgtable(struct domain *d)
     return pg;
 }
 
+bool arch_iommu_use_permitted(const struct domain *d)
+{
+    /*
+     * Prevent device assign if mem paging, mem sharing or log-dirty
+     * have been enabled for this domain.
+     */
+    return d == dom_io ||
+           (likely(!mem_sharing_enabled(d)) &&
+            likely(!vm_event_check_ring(d->vm_event_paging)) &&
+            likely(!p2m_get_hostp2m(d)->global_logdirty));
+}
+
 /*
  * Local variables:
  * mode: C

xen/include/xen/iommu.h

@@ -378,6 +378,8 @@ DECLARE_PER_CPU(bool_t, iommu_dont_flush_iotlb);
 extern struct spinlock iommu_pt_cleanup_lock;
 extern struct page_list_head iommu_pt_cleanup_list;
 
+bool arch_iommu_use_permitted(const struct domain *d);
+
 #endif /* _IOMMU_H_ */
 
 /*