linux-kernel - Re: [PATCH] x86/special_insn: reverse __force

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Date:   Wed, 2 Sep 2020 14:54:02 +0200
From:   peterz@...radead.org
To:     Nadav Amit <nadav.amit@...il.com>
Cc:     linux-kernel@...r.kernel.org, Thomas Gleixner <tglx@...utronix.de>,
        Nadav Amit <namit@...are.com>, Ingo Molnar <mingo@...hat.com>,
        Borislav Petkov <bp@...en8.de>, x86@...nel.org,
        "H. Peter Anvin" <hpa@...or.com>,
        Andy Lutomirski <luto@...nel.org>,
        Kees Cook <keescook@...omium.org>, stable@...r.kernel.org
Subject: Re: [PATCH] x86/special_insn: reverse __force_order logic

On Tue, Sep 01, 2020 at 09:18:57AM -0700, Nadav Amit wrote:

> Unless I misunderstand the logic, __force_order should also be used by
> rdpkru() and wrpkru() which do not have dependency on __force_order. I
> also did not understand why native_write_cr0() has R/W dependency on
> __force_order, and why native_write_cr4() no longer has any dependency
> on __force_order.

There was a fairly large thread about this thing here:

  https://lkml.kernel.org/r/20200527135329.1172644-1-arnd@arndb.de

I didn't keep up, but I think the general concensus was that it's
indeed a bit naf.