xen/arm: Allow device-passthrough even the IOMMU is off

At the moment, we are only supporting device-passthrough when Xen has
enabled the IOMMU. There are some use cases where it is not possible to
use the IOMMU (e.g. doesn't exist, hardware limitation, performance) yet
it would be OK to assign a device to trusted domain so long they are
direct-mapped or the device doesn't do DMA.

Note that when the IOMMU is disabled, it will be necessary to add
xen,force-assign-without-iommu for every device that needs to be assigned.

Signed-off-by: Stefano Stabellini <stefano.stabellini@xilinx.com>
Signed-off-by: Penny Zheng <penny.zheng@arm.com>
Tested-by: Stefano Stabellini <sstabellini@kernel.org>
Acked-by: Julien Grall <jgrall@amazon.com>

diff --git a/xen/arch/arm/domain_build.c b/xen/arch/arm/domain_build.c
index 6467e8ee32819c6c54410febda50d2fc69c2c492..c1e8c99f64d723ad41cee29f262326c1df9ba3a6 100644 (file)
--- a/xen/arch/arm/domain_build.c
+++ b/xen/arch/arm/domain_build.c
@@ -3047,7 +3047,8 @@ void __init create_domUs(void)
             panic("Missing property 'cpus' for domain %s\n",
                   dt_node_name(node));
 
-        if ( dt_find_compatible_node(node, NULL, "multiboot,device-tree") )
+        if ( dt_find_compatible_node(node, NULL, "multiboot,device-tree") &&
+             iommu_enabled )
             d_cfg.flags |= XEN_DOMCTL_CDF_iommu;
 
         if ( !dt_property_read_u32(node, "nr_spis", &d_cfg.arch.nr_spis) )