linux-kernel - Re: [PATCH v11 13/21] KVM: selftests: Add helpers to init TDX memory and finalize VM

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Message-ID: <aPui50JMEcuIl7-8@google.com>
Date: Fri, 24 Oct 2025 09:01:43 -0700
From: Sean Christopherson <seanjc@...gle.com>
To: Sagi Shahar <sagis@...gle.com>
Cc: Ira Weiny <ira.weiny@...el.com>, linux-kselftest@...r.kernel.org, 
	Paolo Bonzini <pbonzini@...hat.com>, Shuah Khan <shuah@...nel.org>, 
	Ackerley Tng <ackerleytng@...gle.com>, Ryan Afranji <afranji@...gle.com>, 
	Andrew Jones <ajones@...tanamicro.com>, Isaku Yamahata <isaku.yamahata@...el.com>, 
	Erdem Aktas <erdemaktas@...gle.com>, Rick Edgecombe <rick.p.edgecombe@...el.com>, 
	Roger Wang <runanwang@...gle.com>, Binbin Wu <binbin.wu@...ux.intel.com>, 
	Oliver Upton <oliver.upton@...ux.dev>, "Pratik R. Sampat" <pratikrajesh.sampat@....com>, 
	Reinette Chatre <reinette.chatre@...el.com>, Chao Gao <chao.gao@...el.com>, 
	Chenyi Qiang <chenyi.qiang@...el.com>, linux-kernel@...r.kernel.org, kvm@...r.kernel.org
Subject: Re: [PATCH v11 13/21] KVM: selftests: Add helpers to init TDX memory
 and finalize VM

On Thu, Oct 23, 2025, Sagi Shahar wrote:
> On Wed, Oct 15, 2025 at 11:25 AM Ira Weiny <ira.weiny@...el.com> wrote:
> >
> > Sagi Shahar wrote:
> > > From: Ackerley Tng <ackerleytng@...gle.com>
> > >
> >
> > [snip]
> >
> > > diff --git a/tools/testing/selftests/kvm/lib/x86/tdx/tdx_util.c b/tools/testing/selftests/kvm/lib/x86/tdx/tdx_util.c
> > > index 2551b3eac8f8..53cfadeff8de 100644
> > > --- a/tools/testing/selftests/kvm/lib/x86/tdx/tdx_util.c
> > > +++ b/tools/testing/selftests/kvm/lib/x86/tdx/tdx_util.c
> > > @@ -270,3 +270,61 @@ void vm_tdx_init_vm(struct kvm_vm *vm, uint64_t attributes)
> > >
> > >       free(init_vm);
> > >  }
> > > +
> >
> > [snip]
> >
> > > +
> > > +void vm_tdx_finalize(struct kvm_vm *vm)
> >
> > Why is this not a new kvm_arch_vm_finalize_vcpu() call?
> 
> What do you mean?

Ira is pointing out that upstream now has kvm_arch_vm_finalize_vcpus(), so you
can (and I agree, should) implement that for x86.c, and do vm_tdx_finalize() from
there (based on the VM shape) instead of requiring the caller to manually finalize
the TD.

Unlike SEV, where userspace can manipulate guest state prior to LAUNCH, TDX guest
state is unreachable from time zero, i.e. there is unlikely to be many (any?) use
cases where a selftest wants to do something between creating vCPUs and finalizing
the TD.