Re: [RFC PATCH 02/15] x86/tdx: Add TDCM hypercall wrapper for TDX Connect

[Nikolay Borisov]

On 24.09.26 г. 7:10 ч., Zhenzhong Duan wrote:
> TDX Connect is a TDX feature that enables secure device assignment,
> allowing a TDX guest to directly interact with TEE-IO capable devices.
>
> The TEE-IO Device Control and Management (TDCM) hypercall
> (TDG.VP.VMCALL<TDCM>, defined in TDX GHCI v2.0 specification) is the
> primary interface through which a TDX guest issues device management
> commands to the host. The host processes these commands and returns
> responses via a shared memory buffer.

This patch contradicts what's going in patch 5. Because you make it 
sound as if TDCM is yet another leaf of VP.VMCALL, but then in patch 5 
you introduce the polling code to read the result. And there is not 
enough information in the changelogs to understand why this added 
complexity is needed. Isn't TDCM handled synchronously by the VMM as the 
rest of the tdcalls, is it perhaps handled by TDX NRX module?

> Abstract the underlying leaf call and pass the shared buffer physical
> address as a decrypted mapping. Add a runtime page alignment check
> for the buffer to enforce correct usage.

<snip>