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Wed, 24 Jun 2020 07:06:50 +0000 (UTC) Date: Wed, 24 Jun 2020 09:06:48 +0200 From: Cornelia Huck To: Christian Borntraeger Subject: Re: [PATCH v3 0/9] Generalize memory encryption models Message-ID: <20200624090648.6bdf82bd.cohuck@redhat.com> In-Reply-To: <2fa7c84a-6929-ef04-1d61-f76a4cac35f5@de.ibm.com> References: <20200619020602.118306-1-david@gibson.dropbear.id.au> <2fa7c84a-6929-ef04-1d61-f76a4cac35f5@de.ibm.com> Organization: Red Hat GmbH MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 2.84 on 10.5.11.22 Received-SPF: pass client-ip=207.211.31.120; envelope-from=cohuck@redhat.com; helo=us-smtp-1.mimecast.com X-detected-operating-system: by eggs.gnu.org: First seen = 2020/06/24 02:33:25 X-ACL-Warn: Detected OS = Linux 2.2.x-3.x [generic] [fuzzy] X-Spam_score_int: -30 X-Spam_score: -3.1 X-Spam_bar: --- X-Spam_report: (-3.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-1, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H3=-0.01, RCVD_IN_MSPIKE_WL=-0.01, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=_AUTOLEARN X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: pair@us.ibm.com, brijesh.singh@amd.com, frankja@linux.ibm.com, kvm@vger.kernel.org, mst@redhat.com, david@redhat.com, qemu-devel@nongnu.org, Eduardo Habkost , dgilbert@redhat.com, pasic@linux.ibm.com, qemu-s390x@nongnu.org, qemu-ppc@nongnu.org, pbonzini@redhat.com, Richard Henderson , mdroth@linux.vnet.ibm.com, David Gibson Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On Mon, 22 Jun 2020 16:27:28 +0200 Christian Borntraeger wrote: > On 19.06.20 04:05, David Gibson wrote: > > A number of hardware platforms are implementing mechanisms whereby the > > hypervisor does not have unfettered access to guest memory, in order > > to mitigate the security impact of a compromised hypervisor. > > > > AMD's SEV implements this with in-cpu memory encryption, and Intel has > > its own memory encryption mechanism. POWER has an upcoming mechanism > > to accomplish this in a different way, using a new memory protection > > level plus a small trusted ultravisor. s390 also has a protected > > execution environment. > > > > The current code (committed or draft) for these features has each > > platform's version configured entirely differently. That doesn't seem > > ideal for users, or particularly for management layers. > > > > AMD SEV introduces a notionally generic machine option > > "machine-encryption", but it doesn't actually cover any cases other > > than SEV. > > > > This series is a proposal to at least partially unify configuration > > for these mechanisms, by renaming and generalizing AMD's > > "memory-encryption" property. It is replaced by a > > "host-trust-limitation" property pointing to a platform specific > > object which configures and manages the specific details. > > > > For now this series covers just AMD SEV and POWER PEF. I'm hoping it > > can be extended to cover the Intel and s390 mechanisms as well, > > though. > > Let me try to summarize what I understand what you try to achieve: > one command line parameter for all platforms that > > common across all platforms: > - disable KSM > - by default enables iommu_platform > > > per platform: > - setup the necessary encryption scheme when appropriate > - block migration > -.... > > > The tricky part is certainly the per platform thing. For example on > s390 we just have a cpumodel flag that provides interfaces to the guest > to switch into protected mode via the ultravisor. This works perfectly > fine with the host model, so no need to configure anything. The platform > code then disables KSM _on_switchover_ and not in general. Because the > guest CAN switch into protected, but it does not have to. > > So this feels really hard to do right. Would a virtual BoF on KVM forum > be too late? We had a BoF on protected guests last year and that was > valuable. Maybe we can do some kind of call to discuss this earlier? (Maybe in the KVM call slot on Tuesdays?) I think it would be really helpful if everybody would have at least a general understanding about how encryption/protection works on the different architectures.