linux-kernel - Re: strace of io

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Message-Id: <d57e169a-55a0-4fa2-a7f2-9a462a786a38@www.fastmail.com>
Date:   Thu, 23 Jul 2020 09:37:40 -0400
From:   "Colin Walters" <walters@...bum.org>
To:     "Stefano Garzarella" <sgarzare@...hat.com>,
        "Andy Lutomirski" <luto@...nel.org>
Cc:     "Jens Axboe" <axboe@...nel.dk>, "Christoph Hellwig" <hch@....de>,
        "Kees Cook" <keescook@...omium.org>,
        "Pavel Begunkov" <asml.silence@...il.com>,
        "Miklos Szeredi" <miklos@...redi.hu>,
        "Matthew Wilcox" <willy@...radead.org>,
        "Jann Horn" <jannh@...gle.com>,
        "Christian Brauner" <christian.brauner@...ntu.com>,
        strace-devel@...ts.strace.io, io-uring@...r.kernel.org,
        "Linux API" <linux-api@...r.kernel.org>,
        "Linux FS Devel" <linux-fsdevel@...r.kernel.org>,
        LKML <linux-kernel@...r.kernel.org>,
        "Michael Kerrisk" <mtk.manpages@...il.com>,
        "Stefan Hajnoczi" <stefanha@...hat.com>
Subject: Re: strace of io_uring events?

On Tue, Jul 21, 2020, at 11:58 AM, Stefano Garzarella wrote:

> my use case concerns virtualization. The idea, that I described in the
> proposal of io-uring restrictions [1], is to share io_uring CQ and SQ queues
> with a guest VM for block operations.

Virtualization being a strong security barrier is in eternal conflict with maximizing performance.
All of these "let's add a special guest/host channel" are high risk areas.

And this effort in particular - is it *really* worth it to expose a brand new, fast moving Linux kernel interface (that probably hasn't been fuzzed as much as it needs to be) to virtual machines?

People who want maximum performance at the cost of a bit of security already have the choice to use Linux containers, where they can use io_uring natively.