linux-kernel - Re: [Part1 PATCH v4 15/17] percpu: introduce DEFINE_PER_CPU

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Message-ID: <20170919031344.GL378890@devbig577.frc2.facebook.com>
Date:   Mon, 18 Sep 2017 20:13:44 -0700
From:   Tejun Heo <tj@...nel.org>
To:     Brijesh Singh <brijesh.singh@....com>
Cc:     linux-kernel@...r.kernel.org, x86@...nel.org, kvm@...r.kernel.org,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>,
        "H . Peter Anvin" <hpa@...or.com>, Borislav Petkov <bp@...e.de>,
        Andy Lutomirski <luto@...nel.org>,
        Tom Lendacky <thomas.lendacky@....com>,
        Arnd Bergmann <arnd@...db.de>,
        Christoph Lameter <cl@...ux.com>, linux-arch@...r.kernel.org
Subject: Re: [Part1 PATCH v4 15/17] percpu: introduce
 DEFINE_PER_CPU_UNENCRYPTED

On Sat, Sep 16, 2017 at 07:34:16AM -0500, Brijesh Singh wrote:
> When SEV is active, memory is encrypted with guest-specific key, and if
> guest OS wants to share the memory region with hypervisor then it must
> clear the C-bit (i.e set unencrypted) before sharing it.
> 
> DEFINE_PER_CPU_UNENCRYPTED can be used to define the per-cpu variables
> which will be shared between guest and hypervisor. Currently, KVM defines
> three variables (steal-time, apf_reason, and avic_eio) which are shared
> with 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>

Thanks.

-- 
tejun