iommu/amd: Finish TLB flush in amd_iommu_unmap()

BugLink: http://bugs.launchpad.net/bugs/1724836

commit ce76353f upstream.

The function only sends the flush command to the IOMMU(s),
but does not wait for its completion when it returns. Fix
that.

Fixes: 601367d7 ('x86/amd-iommu: Remove iommu_flush_domain function')
Signed-off-by: Joerg Roedel <jroedel@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Stefan Bader <stefan.bader@canonical.com>
Signed-off-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com>

drivers/iommu/amd_iommu.c

@@ -3096,6 +3096,7 @@ static size_t amd_iommu_unmap(struct iommu_domain *dom, unsigned long iova,
 	mutex_unlock(&domain->api_lock);
 
 	domain_flush_tlb_pde(domain);
+	domain_flush_complete(domain);
 
 	return unmap_size;
 }