RE: [PATCH v5 09/11] iommu/vt-d: Add iotlb flush for nested domain

From: Liu, Yi L yi.l.liu@intel.com Sent: Thursday, September 21, 2023 3:54 PM

• /* REVISIT:

• * VT-d has defined ITE, ICE, IQE for invalidation failure per hardware,
  

• * but no error code yet, so just set the error code to be 0.
  

• */
  

• *cerror_idx = 0;

Is it "hardware doesn't provide error code now though it's defined in spec" or "intel-iommu driver doesn't retrieve the error code though it's provided by the hardware"?

Is there guarantee that '0' isn't used for an existing error code or won't be used for any new error code later?