On 4/26/23 10:51 AM, Sean Christopherson wrote: > On Wed, Apr 26, 2023, Carlos Bilbao wrote: >> Hello Sean, >> >> On 4/26/23 8:32 AM, Reshetova, Elena wrote: >>> Hi Sean, >>> >>> Thank you for your review! Please see my comments inline. >>> >>>> On Mon, Mar 27, 2023, Carlos Bilbao wrote: > > ... > >>>>> More details on the x86-specific solutions can be >>>>> +found in >>>>> +:doc:`Intel Trust Domain Extensions (TDX) </x86/tdx>` and >>>>> +:doc:`AMD Memory Encryption </x86/amd-memory-encryption>`. >>>> >>>> So by the above definition, vanilla SEV and SEV-ES can't be considered CoCo. SEV >>>> doesn't provide anything besides increased confidentiality of guest memory, and >>>> SEV-ES doesn't provide integrity or validation of physical page assignment. >>>> >>> >>> Same >>> >> >> Personally, I think it's reasonable to mention SEV/SEV-ES in the context of >> confidential computing and acknowledge their relevance in this area. >> >> But there is no mention to SEV or SEV-ES in this draft. And the document we >> reference there covers AMD-SNP, which provides integrity. > > ... > >>>>> +While the traditional hypervisor has unlimited access to guest data and >>>>> +can leverage this access to attack the guest, the CoCo systems mitigate >>>>> +such attacks by adding security features like guest data confidentiality >>>>> +and integrity protection. This threat model assumes that those features >>>>> +are available and intact. >>>> >>>> Again, if you're claiming integrity is a key tenant, then SEV and SEV-ES can't be >>>> considered CoCo. >> >> Again, nobody mentioned SEV/SEV-ES here. > > Yes, somebody did. Unless your dictionary has a wildly different definition for > "all". > > : +Overview and terminology > : +======================== > : + > : +Confidential Cloud Computing (CoCo) refers to a set of HW and SW > : +virtualization technologies that allow Cloud Service Providers (CSPs) to > : +provide stronger security guarantees to their clients (usually referred to > : +as tenants) by excluding all the CSP's infrastructure and SW out of the > : +tenant's Trusted Computing Base (TCB). > : + > : +While the concrete implementation details differ between technologies, all > ^^^ > : +of these mechanisms provide increased confidentiality and integrity of CoCo > : +guest memory and execution state (vCPU registers), more tightly controlled > : +guest interrupt injection, as well as some additional mechanisms to control > : +guest-host page mapping. More details on the x86-specific solutions can be > : +found in > > This document is named confidential-computing.rst, not tdx-and-snp.rst. Not > explicitly mentioning SEV doesn't magically warp reality to make descriptions like > this one from security/secrets/coco.rst disappear: > > Introduction > ============ > > Confidential Computing (coco) hardware such as AMD SEV (Secure Encrypted > Virtualization) allows guest owners to inject secrets into the VMs > memory without the host/hypervisor being able to read them. > > My complaint about this document being too Intel/AMD centric isn't that it doesn't > mention other implementations, it's that the doc describes CoCo purely from the > narrow viewpoint of Intel TDX and AMD SNP, and to be blunt, reads like a press > release and not an objective overview of CoCo. Be specific about the parts of the document that you feel are too AMD/Intel centric, and we will correct them. Thanks, Carlos
