linux-kernel - Re: [PATCH v2 00/21] Runtime TDX Module update support

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: <45c85e40-d049-4242-a251-d541e60d6e7d@intel.com>
Date: Fri, 24 Oct 2025 13:14:50 -0700
From: Dave Hansen <dave.hansen@...el.com>
To: Sean Christopherson <seanjc@...gle.com>, dan.j.williams@...el.com
Cc: Chao Gao <chao.gao@...el.com>, Vishal Annapurve <vannapurve@...gle.com>,
 Elena Reshetova <elena.reshetova@...el.com>,
 "linux-coco@...ts.linux.dev" <linux-coco@...ts.linux.dev>,
 "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
 "x86@...nel.org" <x86@...nel.org>,
 Reinette Chatre <reinette.chatre@...el.com>, Ira Weiny
 <ira.weiny@...el.com>, Kai Huang <kai.huang@...el.com>,
 "yilun.xu@...ux.intel.com" <yilun.xu@...ux.intel.com>,
 "sagis@...gle.com" <sagis@...gle.com>,
 "paulmck@...nel.org" <paulmck@...nel.org>,
 "nik.borisov@...e.com" <nik.borisov@...e.com>, Borislav Petkov
 <bp@...en8.de>, Dave Hansen <dave.hansen@...ux.intel.com>,
 "H. Peter Anvin" <hpa@...or.com>, Ingo Molnar <mingo@...hat.com>,
 "Kirill A. Shutemov" <kas@...nel.org>, Paolo Bonzini <pbonzini@...hat.com>,
 Rick P Edgecombe <rick.p.edgecombe@...el.com>,
 Thomas Gleixner <tglx@...utronix.de>
Subject: Re: [PATCH v2 00/21] Runtime TDX Module update support

On 10/24/25 13:00, Sean Christopherson wrote:
> C'mon people (especially the Google folks), this is the ***exact***
> same problem as certificate updates for SNP[1].  Y'all suggested
> holding a lock across a userspace exit back then, and Dan's analysis
> confirms my reaction from back then that "Holding a lock across an
> exit to userspace seems wildly unsafe."[2]
> 
> In the end, it took more time to understand the problem then to
> sketch out and test a solution[3].
> 
> Unless this somehow puts the host (kernel) at risk, this is a
> userspace problem.

If there's an similar SEV-SNP problem and accepted solution punted to
userspace that TDX can leverage, I'm 100% on board with that. Let's do that.