Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
MIME-Version: 1.0
References: <20210316014027.3116119-1-natet@google.com> <20210402115813.GB17630@ashkalra_ubuntu_server>
 <87bdd3a6-f5eb-91e4-9442-97dfef231640@redhat.com> <936fa1e7755687981bdbc3bad9ecf2354c748381.camel@linux.ibm.com>
In-Reply-To: <936fa1e7755687981bdbc3bad9ecf2354c748381.camel@linux.ibm.com>
From:   Steve Rutherford <srutherford@google.com>
Date:   Thu, 8 Apr 2021 12:48:56 -0700
Message-ID: <CABayD+cBdOMzy7g6X4W-M8ssMpbpDGxFA5o-Nc5CmWi-aeCArQ@mail.gmail.com>
Subject: Re: [RFC v2] KVM: x86: Support KVM VMs sharing SEV context
To:     jejb@linux.ibm.com
Cc:     Paolo Bonzini <pbonzini@redhat.com>,
        Ashish Kalra <ashish.kalra@amd.com>,
        Nathan Tempelman <natet@google.com>,
        Tom Lendacky <thomas.lendacky@amd.com>,
        X86 ML <x86@kernel.org>, KVM list <kvm@vger.kernel.org>,
        LKML <linux-kernel@vger.kernel.org>,
        Sean Christopherson <seanjc@google.com>,
        David Rientjes <rientjes@google.com>,
        Brijesh Singh <brijesh.singh@amd.com>,
        dovmurik@linux.vnet.ibm.com, lersek@redhat.com, frankeh@us.ibm.com
Content-Type: text/plain; charset="UTF-8"
Precedence: bulk

On Thu, Apr 8, 2021 at 10:43 AM James Bottomley <jejb@linux.ibm.com> wrote:
>
> On Fri, 2021-04-02 at 16:20 +0200, Paolo Bonzini wrote:
> > On 02/04/21 13:58, Ashish Kalra wrote:
> > > Hi Nathan,
> > >
> > > Will you be posting a corresponding Qemu patch for this ?
> >
> > Hi Ashish,
> >
> > as far as I know IBM is working on QEMU patches for guest-based
> > migration helpers.
>
> Yes, that's right, we'll take on this part.
>
> > However, it would be nice to collaborate on the low-level (SEC/PEI)
> > firmware patches to detect whether a CPU is part of the primary VM
> > or the mirror.  If Google has any OVMF patches already done for that,
> > it would be great to combine it with IBM's SEV migration code and
> > merge it into upstream OVMF.
>
> We've reached the stage with our prototyping where not having the OVMF
> support is blocking us from working on QEMU.  If we're going to have to
> reinvent the wheel in OVMF because Google is unwilling to publish the
> patches, can you at least give some hints about how you did it?
>
> Thanks,
>
> James

Hey James,
It's not strictly necessary to modify OVMF to make SEV VMs live
migrate. If we were to modify OVMF, we would contribute those changes
upstream.

Thanks,
Steve