linux-kernel - Re: [RFC PATCH 3/4] KVM: TDX: Exit to userspace for GetTdVmCallInfo

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <88c3cd16a24c7318f671223bd65eef63fe276a08.camel@intel.com>
Date: Thu, 12 Jun 2025 08:27:22 +0000
From: "Huang, Kai" <kai.huang@...el.com>
To: "seanjc@...gle.com" <seanjc@...gle.com>, "Edgecombe, Rick P"
	<rick.p.edgecombe@...el.com>
CC: "mikko.ylinen@...ux.intel.com" <mikko.ylinen@...ux.intel.com>, "Shutemov,
 Kirill" <kirill.shutemov@...el.com>, "binbin.wu@...ux.intel.com"
	<binbin.wu@...ux.intel.com>, "Yao, Jiewen" <jiewen.yao@...el.com>, "Li,
 Xiaoyao" <xiaoyao.li@...el.com>, "linux-kernel@...r.kernel.org"
	<linux-kernel@...r.kernel.org>, "Hunter, Adrian" <adrian.hunter@...el.com>,
	"Chatre, Reinette" <reinette.chatre@...el.com>, "kvm@...r.kernel.org"
	<kvm@...r.kernel.org>, "Zhao, Yan Y" <yan.y.zhao@...el.com>, "Lindgren, Tony"
	<tony.lindgren@...el.com>, "Yamahata, Isaku" <isaku.yamahata@...el.com>,
	"pbonzini@...hat.com" <pbonzini@...hat.com>
Subject: Re: [RFC PATCH 3/4] KVM: TDX: Exit to userspace for GetTdVmCallInfo

On Wed, 2025-06-11 at 11:13 -0700, Sean Christopherson wrote:
> On Wed, Jun 11, 2025, Rick P Edgecombe wrote:
> > On Wed, 2025-06-11 at 09:26 -0700, Sean Christopherson wrote:
> > > > GetQuote is not part of the "Base" TDVMCALLs and so has a bit in
> > > > GetTdVmCallInfo. We could move it to base?
> > > 
> > > Is GetQuote actually optional?  TDX without attestation seems rather
> > > pointless.
> > 
> > I don't know if that was a consideration for why it got added to the optional
> > category. The inputs were gathered from more than just Linux.
> 
> If there's an actual use case for TDX without attestation, then by all means,
> make it optional.  I'm genuinely curious if there's a hypervisor that plans on
> productizing TDX without supporting attestation.  It's entirely possible (likely?)
> I'm missing or forgetting something.

With no intention to disrupt this discussion, but even w/o GetQuote TDX can
also support attestation, because TD can just get the TDREPORT and send to
remote Quoting Enclave to get it signed, via whatever communication channel
available (vsock, TCP/IP etc). :-)

It's just not all TDX guests have those communication channels available in
CSP's deployment, and GetQuote can fill up the hole as a last resort.

Of course now TD userspace may choose to only support GetQuote simply
because kernel supports "unified ABI" to return remotely verifiable blob
across vendors, but still ...