Re: [RFC PATCH 09/21] KVM: TDX: Enable 2MB mapping size after TD is RUNNABLE

[Yan Zhao]

On Wed, Jun 25, 2025 at 05:28:22PM +0800, Yan Zhao wrote:
> Write down my understanding to check if it's correct:
> 
> - when a TD is NOT configured to support KVM_LPAGE_GUEST_INHIBIT TDVMCALL, KVM
>   always maps at 4KB
> 
> - When a TD is configured to support KVM_LPAGE_GUEST_INHIBIT TDVMCALL,
Sorry, the two conditions are stale ones. No need any more.
So it's always
 
 (a)
 1. guest accepts at 4KB
 2. TDX sets KVM_LPAGE_GUEST_INHIBIT and try splitting.(with write mmu_lock)
 3. KVM maps at 4KB (with read mmu_lock)
 4. guest's 4KB accept succeeds.
 
 (b)
 1. guest accepts at 2MB.
 2. KVM maps at 4KB due to a certain reason.
 3. guest's accept 2MB fails with TDACCEPT_SIZE_MISMATCH.
 4. guest accepts at 4KB
 5. guest's 4KB accept succeeds.