linux-kernel - Re: [Part1 PATCH v5 15/17] percpu: Introduce DEFINE_PER_CPU

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Date:   Thu, 28 Sep 2017 22:32:19 +0200
From:   Borislav Petkov <bp@...e.de>
To:     Brijesh Singh <brijesh.singh@....com>
Cc:     kvm@...r.kernel.org, linux-kernel@...r.kernel.org, x86@...nel.org,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>,
        "H. Peter Anvin" <hpa@...or.com>, Arnd Bergmann <arnd@...db.de>,
        Tejun Heo <tj@...nel.org>, Christoph Lameter <cl@...ux.com>,
        linux-arch@...r.kernel.org, Tom Lendacky <thomas.lendacky@....com>
Subject: Re: [Part1 PATCH v5 15/17] percpu: Introduce DEFINE_PER_CPU_DECRYPTED

On Wed, Sep 27, 2017 at 10:13:27AM -0500, Brijesh Singh wrote:
> KVM guest defines three per-CPU variables (steal-time, apf_reason, and
> avic_eio) which are shared between a guest and a hypervisor. When SEV
> is active, memory is encrypted with a guest-specific key, and if the
> guest OS wants to share the memory region with the hypervisor then it
> must clear the C-bit (i.e set decrypted) before sharing it.
> 
> DEFINE_PER_CPU_DECRYPTED can be used to define the per-CPU variables
> which will be shared between a guest and a hypervisor.
> 
> Cc: Thomas Gleixner <tglx@...utronix.de>
> Cc: Ingo Molnar <mingo@...hat.com>
> Cc: "H. Peter Anvin" <hpa@...or.com>
> Cc: Borislav Petkov <bp@...e.de>
> Cc: Arnd Bergmann <arnd@...db.de>
> Cc: Tejun Heo <tj@...nel.org>
> Cc: Christoph Lameter <cl@...ux.com>
> Cc: linux-arch@...r.kernel.org
> Cc: x86@...nel.org
> Cc: linux-kernel@...r.kernel.org
> Cc: Tom Lendacky <thomas.lendacky@....com>
> Signed-off-by: Brijesh Singh <brijesh.singh@....com>
> Acked-by: Tejun Heo <tj@...nel.org>
> ---
>  include/asm-generic/vmlinux.lds.h | 19 +++++++++++++++++++
>  include/linux/percpu-defs.h       | 15 +++++++++++++++
>  2 files changed, 34 insertions(+)

Reviewed-by: Borislav Petkov <bp@...e.de>

-- 
Regards/Gruss,
    Boris.

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