linux-kernel - Re: [RFC Part1 PATCH v3 13/17] x86/io: Unroll string I/O when SEV is active

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Date:   Fri, 15 Sep 2017 18:22:56 +0200
From:   Borislav Petkov <bp@...e.de>
To:     Brijesh Singh <brijesh.singh@....com>
Cc:     Tom Lendacky <thomas.lendacky@....com>,
        "H. Peter Anvin" <hpa@...or.com>, Arnd Bergmann <arnd@...db.de>,
        David Laight <David.Laight@...lab.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "x86@...nel.org" <x86@...nel.org>,
        "linux-efi@...r.kernel.org" <linux-efi@...r.kernel.org>,
        "linuxppc-dev@...ts.ozlabs.org" <linuxppc-dev@...ts.ozlabs.org>,
        "kvm@...r.kernel.org" <kvm@...r.kernel.org>,
        Fenghua Yu <fenghua.yu@...el.com>,
        Matt Fleming <matt@...eblueprint.co.uk>,
        David Howells <dhowells@...hat.com>,
        Paul Mackerras <paulus@...ba.org>,
        Christoph Lameter <cl@...ux.com>,
        Jonathan Corbet <corbet@....net>,
        Radim Krcmár <rkrcmar@...hat.com>,
        Piotr Luc <piotr.luc@...el.com>,
        Ingo Molnar <mingo@...hat.com>,
        Dave Airlie <airlied@...hat.com>,
        Kees Cook <keescook@...omium.org>,
        Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>,
        Reza Arbab <arbab@...ux.vnet.ibm.com>,
        Andy Lutomirski <luto@...nel.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Laura Abbott <labbott@...hat.com>,
        Tony Luck <tony.luck@...el.com>, Ard.Biesheuvel@...or.com
Subject: Re: [RFC Part1 PATCH v3 13/17] x86/io: Unroll string I/O when SEV is
 active

On Fri, Sep 15, 2017 at 09:48:53AM -0500, Brijesh Singh wrote:
> I see the similar issue with non SEV guest with my simple patch below.
> Guest will reboot as soon as it tries to enable the key.

Can't do it there as the pagetable is not setup yet and you're probably
getting a #PF on any of the derefs down the static_key_enable() path.

I guess one possible place to enable the static key would be in
mem_encrypt_init() where everything should be set up already.

-- 
Regards/Gruss,
    Boris.

SUSE Linux GmbH, GF: Felix Imendörffer, Jane Smithard, Graham Norton, HRB 21284 (AG Nürnberg)
--