xen/swiotlb: Simplify the logic.

Its pretty easy:
 1). We only check to see if we need Xen SWIOTLB for PV guests.
 2). If swiotlb=force or iommu=soft is set, then Xen SWIOTLB will
     be enabled.
 3). If it is an initial domain, then Xen SWIOTLB will be enabled.
 4). Native SWIOTLB must be disabled for PV guests.

Acked-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>

diff --git a/arch/x86/xen/pci-swiotlb-xen.c b/arch/x86/xen/pci-swiotlb-xen.c
index 967633ad98c48b262cf7739c7cdcdb7b8d79641a..b6a534002ab2adda118bfb19814ecf5a584b72cd 100644 (file)
--- a/arch/x86/xen/pci-swiotlb-xen.c
+++ b/arch/x86/xen/pci-swiotlb-xen.c
@@ -34,19 +34,20 @@ static struct dma_map_ops xen_swiotlb_dma_ops = {
 int __init pci_xen_swiotlb_detect(void)
 {
 
+       if (!xen_pv_domain())
+               return 0;
+
        /* If running as PV guest, either iommu=soft, or swiotlb=force will
         * activate this IOMMU. If running as PV privileged, activate it
         * irregardless.
         */
-       if ((xen_initial_domain() || swiotlb || swiotlb_force) &&
-           (xen_pv_domain()))
+       if ((xen_initial_domain() || swiotlb || swiotlb_force))
                xen_swiotlb = 1;
 
        /* If we are running under Xen, we MUST disable the native SWIOTLB.
         * Don't worry about swiotlb_force flag activating the native, as
         * the 'swiotlb' flag is the only one turning it on. */
-       if (xen_pv_domain())
-               swiotlb = 0;
+       swiotlb = 0;
 
        return xen_swiotlb;
 }