This is a real bug fix and a genuine net simplification — +37/-53 while making the code more correct is the right direction. Approving.

The problem is well identified. rocBLAS handles are cached and reused across calls, so if rocblas_native_func threw between the set_pointer_mode(device) and the manual set_pointer_mode(host) at the bottom, the handle stayed in device mode for every subsequent caller — and the next routine passing a host address for a scalar argument would have rocBLAS dereference it on the device. That's a nasty, action-at-a-distance failure mode, and the old comment block ("we need to reset this to the default value in order to avoid invalid memory accesses") shows the hazard was known but only handled on the happy path. RAII is exactly the right fix.

I verified the conversion is complete — I checked every remaining rocblas_set_pointer_mode occurrence in rocblas_level1.cpp at your head commit, and all 11 hits are inside comments (plus one long-dead commented-out call in rot). No live call site was left on the old manual pattern, and level2/level3/extensions/batch never used it. Nice job not leaving the cleanup half-done — that's usually where these go wrong.

Details I liked: deleting copy/assign, and seeding previous_ to rocblas_pointer_mode_host before the get so a failed query still degrades to the sane default rather than to garbage.

Two small things, neither blocking:

1. Unchecked rocBLAS status. The constructor ignores the return of both rocblas_get_pointer_mode and rocblas_set_pointer_mode, while the rest of this backend routes rocBLAS calls through the error-checking helpers. The destructor obviously can't throw, so leave that one alone — but it'd be more consistent to check in the constructor. The old code ignored these too, so this isn't a regression either way.

2. Behavior change worth naming explicitly. The old code unconditionally forced the mode back to host; the guard restores whatever was there on entry. Since every call site now goes through the guard, the invariant holds and I think your version is the more principled one. But it does remove an accidental self-healing property: if some other path ever leaked device mode, the old code would have normalized it back and the guard won't. I'm fine with this — just flagging it so the change is deliberate rather than incidental.

One thing I noticed that is out of scope for this PR — no action wanted here: the USM overloads of dot, sdsdot, rotg, rotm, and rotmg never set device pointer mode at all, while the USM asum/iamax/iamin/nrm2 do. That asymmetry predates your change. If it's a real gap it deserves its own issue; please don't grow this PR to cover it.

Approved: sound, focused fix with strong rationale and validation. The CI testing gap is worth noting but non-blocking.

• The RAII guard correctly restores pointer mode during exceptions, covers all 13 former manual reset sites, and checks constructor operations. This matches rocBLAS pointer-mode semantics. AMD documentation (https://rocm.docs.amd.com/projects/rocBLAS/en/develop/reference/helper-functions.html)
• The primary commit message is excellent.
• No automated rocBLAS regression test was added but the reported MI210 results are persuasive.