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Re: [PATCH v4 1/3] arm,smmu: switch to using iommu_fwspec functions

Hi Stefano,

On 17/07/2021 00:59, Stefano Stabellini wrote:
diff --git a/xen/drivers/passthrough/device_tree.c 
index 999b831d90..911f82a561 100644
--- a/xen/drivers/passthrough/device_tree.c
+++ b/xen/drivers/passthrough/device_tree.c
@@ -140,8 +140,12 @@ int iommu_add_dt_device(struct dt_device_node *np)
      if ( !ops )
          return -EINVAL;
+ /*
+     * Device already added. It can happen when both iommus and
+     * mmu-masters are present.
+     */

This is common code. So I would suggest to write a generic comment to avoid any misunderstanding. The one added just after the call in iommu_do_domctl() would seem more suitable.

      if ( dev_iommu_fwspec_get(dev) )
-        return -EEXIST;
+        return 0;
There are a few things to mention here:

 1) The change is not explained in the commit message
2) One of the caller was checking -EEXIST. As you dropped the only place where -EEXIST should be returned, can you drop the check in the caller?

Ideally this should be in a separate patch because this change is not entirely related to this patch.


Julien Grall



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