Messages in this thread | | | Date | Fri, 22 Jul 2022 14:18:58 -0700 | Subject | Re: [PATCH v8 5/5] x86/tdx: Add Quote generation support | From | Sathyanarayanan Kuppuswamy <> |
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+ Jun
On 7/22/22 12:13 PM, Dave Hansen wrote: > On 7/22/22 12:05, Isaku Yamahata wrote: >>> So, the quote portion of this is basically a bidirectional blob sender. >>> It's to send a blob between guest userspace to host userspace. >>> >>> Do we *REALLY* need specific driver functionality for this? For >>> instance, is there no existing virtio device that can send blobs back >>> and forth? >> It's virtio-vsock. If virtio-vsock is available, the communication works. >> However, some users would like to disable virtio-vsock on their environment for >> some reasons. Even virtio at all. Especially for confidential computing use >> case. It's their choice. It can't be assumed that virtio is available. >> >> The goal is VMM-agnostic (but TDX-specific) interface for that. > > You're basically saying that every confidential computing technology > should have its own host user <-> guest kernel <-> guest user ABI. > That's insanity. If we do this, we need *one* interface that says "talk > to the hypervisor" that's common for all hypervisors and hardware > vendors, or at least more than *one*. > > We don't need a way to talk to hypervisors for Intel systems and another > for AMD and yet another on whatever.
For cases where your platform does not want to support or enable the generic interface (like vsock), isn't it better to have a fallback approach? I am not saying we should have such an ABI for all cases. But attestation is a must-have feature for the TDX guest, and we want to support it in all TD guest platforms. I think the GHCI ABI is added to meet this requirement.
Jun/Isaku, if you are aware of the exact requirement for this hypercall, please share it. Also let us know your comments on this topic.
-- Sathyanarayanan Kuppuswamy Linux Kernel Developer
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