igb(4): Fix out-of-bounds register access on VFs

[kgalazka]

Summary

Virtual Functions have access to a limited number of registers,
and their bus space size is lower. Use KASSERT to detect out-of-bounds
access and eliminate them to avoid kernel panics in production
environment.

Signed-off-by: Krzysztof Galazka <[e-mail]>

[jmg]

[kgalazka]

Wake-on-Lan configuration is not available for VFs.

[erj]

sys/dev/e1000/if_em.c

1585

I wish these checks against !sc->vf_ifp were replaced with something like a E1000_IS_VF() macro, but is that what that check is for?

4382

Interesting...?

[mateusz.moga_intel.com]

green light from validation point of view

[kgalazka]

sys/dev/e1000/if_em.c

1585

Yeah, I was thinking about some refactoring, but I would prefer to do it as separate patch if you don't mind.

[erj]

sys/dev/e1000/if_em.c

1585

Sure.