[Qemu-devel] [PATCH] hw/arm/smmuv3: fix smmu emulation when guest smmu is in passthrough mode

[Jia He <hejianet@gmail.com>]

There is an exception when I passes iommu.passthrough=1 to guest's
kernel boot parameter(host QDF2400 kernel 4.17, guest kernel 4.14).
The guest will be hang when booting up.

When guest smmu is in passthrough mode, entry.perm will not be assigned
to flag in smmuv3_translate. It seems not be correct.

After this patch, I have tested in 4 cases and all passed.
host smmu on/passthrough + guest smmu on/passthrough

Signed-off-by: jia.he@hxt-semitech.com
---
 hw/arm/smmuv3.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/hw/arm/smmuv3.c b/hw/arm/smmuv3.c
index 42dc521..5c46102 100644
--- a/hw/arm/smmuv3.c
+++ b/hw/arm/smmuv3.c
@@ -560,6 +560,12 @@ static IOMMUTLBEntry smmuv3_translate(IOMMUMemoryRegion *mr, hwaddr addr,
     }
 
     ret = smmuv3_decode_config(mr, &cfg, &event);
+
+    if (cfg.bypassed) {
+        ret = 0;
+        goto out;
+    }
+
     if (ret) {
         goto out;
     }
-- 
1.8.3.1