Re: [GIT PULL] x86/iopl changes for v5.5

[Linus Torvalds]

On Mon, Nov 25, 2019 at 8:16 AM Ingo Molnar <mingo@xxxxxxxxxx> wrote:
>
> This tree implements a nice simplification of the iopl and ioperm code
> that Thomas Gleixner discovered: we can implement the IO privilege
> features of the iopl system call by using the IO permission bitmap in
> permissive mode, while trapping CLI/STI/POPF/PUSHF uses in user-space if
> they change the interrupt flag.

I've pulled it.

But do we have a test for something like this:

   ioperm(.. limited set of ports..)
   access that limited set.

   special_sequence() {
       iopl(3);
       access some extended set
       iopl(0)
   }

   go back to access the limited set again

because there's subtle interactions with people using *both* iopl()
and ioperm() and switching between the two. Historically you could
trivially do the above, because they are entirely independent
operations. Does it still work?

Too busy/lazy to check myself.

              Linus