[Xen-devel] [PATCH] xen/arm: Let the IOMMU be accessible by Dom0 if forcibly disabled in Xen

[Oleksandr Tyshchenko <olekstysh@xxxxxxxxx>]

From: Oleksandr Tyshchenko <oleksandr_tyshchenko@xxxxxxxx>

Don't skip IOMMU nodes when creating DT for Dom0 if IOMMU has been
forcibly disabled in bootargs (e.g. "iommu=0") in order to let
the IOMMU be accessible by DOM0.

Signed-off-by: Oleksandr Tyshchenko <oleksandr_tyshchenko@xxxxxxxx>
---
I have heard there is a "possible" case when the IOMMU could be accessible by 
DOM0.
So, I think, for this to work we need to create corresponding DT nodes in the DT
at least.
---
 xen/arch/arm/domain_build.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/xen/arch/arm/domain_build.c b/xen/arch/arm/domain_build.c
index d67f7d4..ff88099 100644
--- a/xen/arch/arm/domain_build.c
+++ b/xen/arch/arm/domain_build.c
@@ -1403,9 +1403,11 @@ static int __init handle_node(struct domain *d, struct 
kernel_info *kinfo,
 
     /*
      * Even if the IOMMU device is not used by Xen, it should not be
-     * passthrough to DOM0
+     * passthrough to DOM0. The exception here is the fact that IOMMU
+     * has been forcibly disabled in bootargs "iommu=0" in order to let
+     * the IOMMU be accessible by DOM0.
      */
-    if ( device_get_class(node) == DEVICE_IOMMU )
+    if ( device_get_class(node) == DEVICE_IOMMU && iommu_enable )
     {
         dt_dprintk(" IOMMU, skip it\n");
         return 0;
-- 
2.7.4


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