Missing validation check for building TLAS and assosicated BLAS in the same vkCmdBuildAccelerationStructuresKHR

[ZilverBlade]

Describe the situation in which you encountered the missing validation
Issue description:
I spent hours debugging why my ray queries didn't work, and the issue was building the TLAS when i had a pending associated BLAS build in the same vkCmdBuildAccelerationStructuresKHR command.

https://docs.vulkan.org/refpages/latest/refpages/source/vkCmdBuildAccelerationStructuresKHR.html

Valid Usage IDs requested
Please include the valid usage IDs for the checks you are requesting:
I couldn't find the VUID for this on the specification page (maybe should be added?). But i think it would go along the lines of: "If a top-level acceleration structure is being built, the associated bottom-level acceleration structure should not be built or updated within the same call"

Additional Context

[artem-lunarg]

@ZilverBlade I am not sure about VUID for this situation (@arno-lunarg do you think it is missing or not needed?), but this should be caught by synchronization validation, please make sure it is enabled. The simplest way is to use vkconfig. All options are provided in the documentation here: https://vulkan.lunarg.com/doc/sdk/1.4.328.1/windows/synchronization_usage.html

[artem-lunarg]

I might be wrong with suggesting syncval. It will detect if there is missing barrier between separate BLAS and TLAS build commands. But it should be possible to detect in Core validation if a single command tries to build both BLAS and TLAS (I actually thought we detect this, but again @arno-lunarg knows better).

[ZilverBlade]

I did indeed have sync layers enabled, and it didn't catch them. I think it's a bit less trivial to validate this since you would have to copy back the instance buffer to host and wait for it to be ready to read back to be able to check if this is correct

[arno-lunarg]

As you mentioned @ZilverBlade, since TLAS reference BLAS through addresses stored in a GPU buffer, you have to look at this buffer to check for this valid usage.
Indeed an explicit VUID seems to be missing, thank you for pointing it out. To me validation for this falls under the "GPU assisted validation" part. I am working on validation in this area, so I will take care of this validation!