[for-4.18][PATCH] xen/arm: Check return code from recursive calls to scan_pfdt_node()

[Michal Orzel <michal.orzel@xxxxxxx>]

At the moment, we do not check a return code from scan_pfdt_node()
called recursively. This means that any issue that may occur while
parsing and copying the passthrough nodes is hidden and Xen continues
to boot a domain despite errors. This may lead to incorrect device tree
generation and various guest issues (e.g. trap on attempt to access MMIO
not mapped in P2M). Fix it.

Fixes: 669ecdf8d6cd ("xen/arm: copy dtb fragment to guest dtb")
Signed-off-by: Michal Orzel <michal.orzel@xxxxxxx>
---
@Henry:
This is a bug fix, so I think we should have it in 4.18 given the possible
consequences I described in the commit msg. I don't see any risks as this change
only checks the return code for an error.
---
 xen/arch/arm/domain_build.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/xen/arch/arm/domain_build.c b/xen/arch/arm/domain_build.c
index 24c9019cc43c..49792dd590ee 100644
--- a/xen/arch/arm/domain_build.c
+++ b/xen/arch/arm/domain_build.c
@@ -2872,8 +2872,11 @@ static int __init scan_pfdt_node(struct kernel_info 
*kinfo, const void *pfdt,
     node_next = fdt_first_subnode(pfdt, nodeoff);
     while ( node_next > 0 )
     {
-        scan_pfdt_node(kinfo, pfdt, node_next, address_cells, size_cells,
-                       scan_passthrough_prop);
+        rc = scan_pfdt_node(kinfo, pfdt, node_next, address_cells, size_cells,
+                            scan_passthrough_prop);
+        if ( rc )
+            return rc;
+
         node_next = fdt_next_subnode(pfdt, node_next);
     }
 
-- 
2.25.1