linux-kernel - Re: [PATCH v1 00/19] x86/insn: Add an insn

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Message-ID: <20210203120037.GA13819@zn.tnic>
Date:   Wed, 3 Feb 2021 13:00:37 +0100
From:   Borislav Petkov <bp@...en8.de>
To:     Tom Lendacky <thomas.lendacky@....com>
Cc:     Andy Lutomirski <luto@...capital.net>,
        Masami Hiramatsu <mhiramat@...nel.org>,
        X86 ML <x86@...nel.org>, LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v1 00/19] x86/insn: Add an insn_decode() API

On Sun, Dec 27, 2020 at 09:26:04AM -0600, Tom Lendacky wrote:
> > We could also say that probably there should be a way to say "decode
> > only the first insn in the buffer and ignore the rest". That is all up
> > to the use cases so I'm looking for suggestions here.
> 
> That's the way it works today, right?  One instruction, no matter the length
> of the buffer (assuming the length is long enough to include a full
> instruction)?
> 
> Because the callers of the decode may rely on parsing only the current
> instruction (like SEV-ES), it should probably default to that (although most
> of the call points are being updated so you could supply a boolean to
> indicate one vs many instructions). The caller doesn't necessarily know the
> length of the instruction, so it may provide a buffer of max instruction
> length.
> 
> Also, if you want to parse more than one instruction at a time, wouldn't you
> need to maintain register context within the parsing, I don't think that is
> done today. Or you could chain together some instruction contexts to
> identify each instruction that was parsed?

Yah, let's leave it all to the one who actually needs multiple insn
parsing.

-- 
Regards/Gruss,
    Boris.

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