linux-kernel - Re: [PATCH 3/6] x86/sev-es: Use __put_user()/__get

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Message-ID: <YJv7n9aZPiQYgdmf@8bytes.org>
Date:   Wed, 12 May 2021 18:00:31 +0200
From:   Joerg Roedel <joro@...tes.org>
To:     Dave Hansen <dave.hansen@...el.com>
Cc:     x86@...nel.org, Hyunwook Baek <baekhw@...gle.com>,
        Joerg Roedel <jroedel@...e.de>, stable@...r.kernel.org,
        hpa@...or.com, Andy Lutomirski <luto@...nel.org>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Jiri Slaby <jslaby@...e.cz>,
        Dan Williams <dan.j.williams@...el.com>,
        Tom Lendacky <thomas.lendacky@....com>,
        Juergen Gross <jgross@...e.com>,
        Kees Cook <keescook@...omium.org>,
        David Rientjes <rientjes@...gle.com>,
        Cfir Cohen <cfir@...gle.com>,
        Erdem Aktas <erdemaktas@...gle.com>,
        Masami Hiramatsu <mhiramat@...nel.org>,
        Mike Stunes <mstunes@...are.com>,
        Sean Christopherson <seanjc@...gle.com>,
        Martin Radev <martin.b.radev@...il.com>,
        Arvind Sankar <nivedita@...m.mit.edu>,
        linux-coco@...ts.linux.dev, linux-kernel@...r.kernel.org,
        kvm@...r.kernel.org, virtualization@...ts.linux-foundation.org
Subject: Re: [PATCH 3/6] x86/sev-es: Use __put_user()/__get_user

On Wed, May 12, 2021 at 08:57:53AM -0700, Dave Hansen wrote:
> The changelog _helps_, but using a "user" function to handle kernel MMIO
> for its error handling properties seems like it's begging for a comment.
> 
> __put_user() also seems to have fun stuff like __chk_user_ptr().  It all
> seems sketchy to me.

Yeah, as Juergen already pointed out, there are certain problems with
that too. But I don't want to write my own accessors, so I will
introduce a separate user and kernel path to these functions.

Regards,

	Joerg