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Date:   Wed, 19 May 2021 13:33:46 +0200
From:   'Joerg Roedel' <joro@8bytes.org>
To:     Joerg Roedel <jroedel@suse.de>
Cc:     Juergen Gross <jgross@suse.com>,
        David Laight <David.Laight@aculab.com>,
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Subject: Re: [PATCH 3/6] x86/sev-es: Use __put_user()/__get_user
Message-ID: <YKT3mpYlPqNHo1QU@8bytes.org>
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On Wed, May 12, 2021 at 11:32:35AM +0200, Joerg Roedel wrote:
> On Wed, May 12, 2021 at 10:58:20AM +0200, Juergen Gross wrote:
> > No, those were used before, but commit 9da3f2b7405440 broke Xen's use
> > case. That is why I did commit 1457d8cf7664f.
>
> [...]
>
> Having the distinction between user and kernel memory accesses
> explicitly in the code seems to be the most robust solution.

On the other hand, as I found out today, 9da3f2b7405440 had a short
life-time and got reverted upstream. So using __get_user()/__put_user()
should be fine in this code path. It just deserves a comment explaining
its use here and why pagefault_enable()/disable() is not needed.
Even the get_kernel* helpers use __get_user_size() internally.

Regards,

	Joerg