[UR][L0] Diagnose errors in host memory registration API#22370
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- The Level Zero driver does not reliably diagnose alignment errors for the external system memory mapping path: an unaligned pointer is reported as ZE_RESULT_ERROR_OUT_OF_HOST_MEMORY and an unaligned size is silently accepted. Validate host-page alignment of the pointer and size directly in the Level Zero adapter. - Validate null pointer and zero size, returning UR_RESULT_ERROR_INVALID_VALUE. - Reject a registration whose range [pHostMem, pHostMem + size) would overflow the host address space, returning UR_RESULT_ERROR_INVALID_VALUE. - Replace the bare assert that the mapped device VA equals the host pointer with a real runtime check: on mismatch, undo the mapping and return an error instead of silently handing back an unusable registration. - Handle UR_DEVICE_INFO_USM_HOST_ALLOC_REGISTER_SUPPORT_EXP in the L0 device info query, returning whether the external system memory mapping extension is supported. The enum existed but was previously unhandled. Assisted-by: Claude
pbalcer
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Jun 19, 2026
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| // This extension maps the existing host memory in place, so the mapped | ||
| // device virtual address must match the host pointer that was registered. | ||
| // If the driver ever returns a different address we cannot honor the | ||
| // contract, so undo the mapping and report a failure rather than silently | ||
| // handing back an unusable registration. | ||
| if (mappedMem != pHostMem) { | ||
| ZE_CALL_NOCHECK(zeMemFree, (hContext->getZeHandle(), mappedMem)); | ||
| return UR_RESULT_ERROR_UNSUPPORTED_FEATURE; | ||
| } | ||
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I think this is a bit overzealous and too defensive. It would be a severe driver bug for this to happen. It's not an error the application can reasonably handle. I think the assert is the correct thing to do here.
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Assisted-by: Claude