From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <linux-kernel-owner@vger.kernel.org>
Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand
        id S936821AbdJQQXO (ORCPT <rfc822;w@1wt.eu>);
        Tue, 17 Oct 2017 12:23:14 -0400
Received: from mail.skyhub.de ([5.9.137.197]:51760 "EHLO mail.skyhub.de"
        rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP
        id S933143AbdJQQXM (ORCPT <rfc822;linux-kernel@vger.kernel.org>);
        Tue, 17 Oct 2017 12:23:12 -0400
Date: Tue, 17 Oct 2017 18:23:04 +0200
From: Borislav Petkov <bp@alien8.de>
To: Brijesh Singh <brijesh.singh@amd.com>,
        Paolo Bonzini <pbonzini@redhat.com>
Cc: x86@kernel.org, Thomas Gleixner <tglx@linutronix.de>,
        Ingo Molnar <mingo@redhat.com>, "H. Peter Anvin" <hpa@zytor.com>,
        Radim =?utf-8?B?S3LEjW3DocWZ?= <rkrcmar@redhat.com>,
        Tom Lendacky <thomas.lendacky@amd.com>, linux-kernel@vger.kernel.org,
        kvm@vger.kernel.org
Subject: Re: [Part1 PATCH v6 16/17] X86/KVM: Decrypt shared per-cpu variables
 when SEV is active
Message-ID: <20171017162303.4vekeemfz7ix2cjg@pd.tnic>
References: <20171016153423.2980-1-brijesh.singh@amd.com>
 <20171016153423.2980-17-brijesh.singh@amd.com>
 <20171016222416.x26tp222x2ox3tkz@pd.tnic>
 <de38a1ba-98f6-e7c8-427d-f717fa126db5@amd.com>
 <20171017082020.ctgjuo4xcvsaitdf@pd.tnic>
 <57ef6c36-1708-56f2-b0ac-ea2267f6aa9d@amd.com>
 <20171017133555.de4omyuoveaijkk6@pd.tnic>
 <35973f2a-664e-97e8-3dba-00db5f8d9719@amd.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=utf-8
Content-Disposition: inline
In-Reply-To: <35973f2a-664e-97e8-3dba-00db5f8d9719@amd.com>
User-Agent: NeoMutt/20170113 (1.7.2)
Sender: linux-kernel-owner@vger.kernel.org
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org

On Tue, Oct 17, 2017 at 10:42:45AM -0500, Brijesh Singh wrote:
> OK, this goes back to your initial feedback during RFC v3 where I tried
> to do similar thing. But since sev_map_percpu_data() uses __init
> functions hence we need to mark the kvm_guest_cpu_init() as __ref but
> you didn't like the idea and asked me to call the sev_map_percpu_data
> from kvm_smp_prepare_boot_cpu() which is already __init.

So looking at this more, I'm wondering how did I miss this: this whole
SEV code doesn't belong in kvm.c but in svm.c! This is AMD-only and
should be there.

Now, for that you need those three percpu variables to not be static but
I think we can do this by adding their declarations to a kvm-internal.h
header which is in arch/x86/kernel/kvm-internal.h, i.e., not in the
include path and only kvm-related units can include it.

@Paolo: thoughts?

Then, you can call sev_map_percpu_data() during module init, i.e.,
svm_init(). Or in one of the init functions you're adding later,
sev_hardware_setup() for example, or so. I.e., one of those init paths.
Because, AFAICT, you want to clear the physical C-bit only once in the
percpu pages.

I think this is much better than the "grafted" situation now.

-- 
Regards/Gruss,
    Boris.

Good mailing practices for 400: avoid top-posting and trim the reply.