linux-kernel - Re: [PATCH v2 0/7] KVM: x86/tdx: Have TDX handle VMXON during bringup

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: <aTY8tkI8gEqtDtHU@intel.com>
Date: Mon, 8 Dec 2025 10:49:26 +0800
From: Chao Gao <chao.gao@...el.com>
To: Sean Christopherson <seanjc@...gle.com>
CC: Thomas Gleixner <tglx@...utronix.de>, Ingo Molnar <mingo@...hat.com>,
	Borislav Petkov <bp@...en8.de>, Dave Hansen <dave.hansen@...ux.intel.com>,
	<x86@...nel.org>, Kiryl Shutsemau <kas@...nel.org>, Paolo Bonzini
	<pbonzini@...hat.com>, <linux-kernel@...r.kernel.org>,
	<linux-coco@...ts.linux.dev>, <kvm@...r.kernel.org>, Dan Williams
	<dan.j.williams@...el.com>
Subject: Re: [PATCH v2 0/7] KVM: x86/tdx: Have TDX handle VMXON during bringup

On Fri, Dec 05, 2025 at 05:10:47PM -0800, Sean Christopherson wrote:
>The idea here is to extract _only_ VMXON+VMXOFF and EFER.SVME toggling.  AFAIK
>there's no second user of SVM, i.e. no equivalent to TDX, but I wanted to keep
>things as symmetrical as possible.
>
>TDX isn't a hypervisor, and isn't trying to be a hypervisor. Specifically, TDX
>should _never_ have it's own VMCSes (that are visible to the host; the
>TDX-Module has it's own VMCSes to do SEAMCALL/SEAMRET), and so there is simply
>no reason to move that functionality out of KVM.
>
>With that out of the way, dealing with VMXON/VMXOFF and EFER.SVME is a fairly
>simple refcounting game.
>
>Decently tested, and it seems like the core idea is sound, so I dropped the
>RFC.  But the side of things definitely needs testing.

I ran tests on an EMR system, including performing CPU hot-{un}plug,
unloading/reloading kvm-intel.ko and launching TDs. No issue found.
So,

Tested-by: Chao Gao <chao.gao@...el.com>