block dangerous passthrough operation

[Christoph Hellwig]

On Wed, Nov 16, 2022 at 09:12:08AM -0700, Keith Busch wrote:
> People do use the fabrics command for 'get property' to check on their
> device, which is a harmless command that you've blocked.

Yeah, I guess read fabrics commnds are ok.

> There are still other harmful things a user could do, like Doorbell
> Buffer Config or Set Feature Host Memory Buffer that could really screw
> things up for the driver. But I think this sets a bad precedence that
> the driver is going to protect an admin user from doing stupid things.
> As more destructive opcodes and features are added in the future, we'd
> be taking on a maintenance burden to analyze all these. Meanwhile, older
> drivers won't provide that protection, so the user is expected to simply
> not do such actions, so why can't they just do that now?

It's a little less about preventing all possible problems, than about
at least letting people known they're doing something totally broken
and not report bugs to me about them..