intel-iommu: Flush unmaps at domain_exit

We typically batch unmaps to be lazily flushed out at
regular intervals.  When we destroy a domain, we need
to force a flush of these lazy unmaps to be sure none
reference the domain we're about to free.

Fixes: https://bugzilla.kernel.org/show_bug.cgi?id=35062
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>
Cc: stable@kernel.org

drivers/pci/intel-iommu.c

@@ -1422,6 +1422,10 @@ static void domain_exit(struct dmar_domain *domain)
 	if (!domain)
 		return;
 
+	/* Flush any lazy unmaps that may reference this domain */
+	if (!intel_iommu_strict)
+		flush_unmaps_timeout(0);
+
 	domain_remove_dev_info(domain);
 	/* destroy iovas */
 	put_iova_domain(&domain->iovad);