Re: [PATCH v4 1/4] KVM: TDX: Synchronize user-return MSRs immediately after VP.ENTER

Adrian Hunter
2025-10-21T13:37:56Z

On 21/10/2025 01:55, Edgecombe, Rick P wrote:
>> + * Several of KVM's user-return MSRs are clobbered by the TDX-Module if
>> + * VP.ENTER succeeds, i.e. on TD-Exit. Mark those MSRs as needing an
>> + * update to synchronize the "current" value in KVM's cache with the
>> + * value in hardware (loaded by the TDX-Module).
>> + */
>
> I think we should be synchronizing only after a successful VP.ENTER with a real
> TD exit, but today instead we synchronize after any attempt to VP.ENTER.

If the MSR's do not get clobbered, does it matter whether or not they get
restored.