From: <dan.j.williams@intel.com>
To: Vishal Annapurve <vannapurve@google.com>, <dan.j.williams@intel.com>
Cc: Dave Hansen <dave.hansen@intel.com>,
Chao Gao <chao.gao@intel.com>,
"Reshetova, Elena" <elena.reshetova@intel.com>,
"linux-coco@lists.linux.dev" <linux-coco@lists.linux.dev>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"x86@kernel.org" <x86@kernel.org>,
"Chatre, Reinette" <reinette.chatre@intel.com>,
"Weiny, Ira" <ira.weiny@intel.com>,
"Huang, Kai" <kai.huang@intel.com>,
"yilun.xu@linux.intel.com" <yilun.xu@linux.intel.com>,
"sagis@google.com" <sagis@google.com>,
"paulmck@kernel.org" <paulmck@kernel.org>,
"nik.borisov@suse.com" <nik.borisov@suse.com>,
Borislav Petkov <bp@alien8.de>,
Dave Hansen <dave.hansen@linux.intel.com>,
"H. Peter Anvin" <hpa@zytor.com>, Ingo Molnar <mingo@redhat.com>,
"Kirill A. Shutemov" <kas@kernel.org>,
Paolo Bonzini <pbonzini@redhat.com>,
"Edgecombe, Rick P" <rick.p.edgecombe@intel.com>,
Thomas Gleixner <tglx@linutronix.de>
Subject: Re: [PATCH v2 00/21] Runtime TDX Module update support
Date: Mon, 27 Oct 2025 11:53:41 -0700 [thread overview]
Message-ID: <68ffbfb53f8b5_10e210078@dwillia2-mobl4.notmuch> (raw)
In-Reply-To: <CAGtprH8g5212M26HPneyaHPq8VKS=x4TU4Q4vbDZqt_gYLO=TA@mail.gmail.com>
Vishal Annapurve wrote:
[..]
> > A theoretical TDX Module change could ensure that atomicity.
>
> IIUC TDX module already supports avoiding this clobber based on the
> TDH.SYS.SHUTDOWN documentation from section 5.4.73 of TDX ABI Spec
> [1].
>
> Host kernel needs to set bit 16 of rcx when invoking TDH.SYS.SHUTDOWN
> is available.
>
> "If supported by the TDX Module, the host VMM can set the
> AVOID_COMPAT_SENSITIVE flag to request the TDX Module to fail
> TDH.SYS.UPDATE if any of the TDs are currently in a state that is
> impacted by the update-sensitive cases."
That is not a fix. That just shifts the complexity from build to update.
It still leaves update in a state where it is not guaranteed to make
forward progress. The way to ensure forward progress is the same as
ensuring build consistency, i.e. sequence build with respect to update.
The kernel sheds complexity by ether making userspace solve that
problem, or motivating a real fix in the TDX Module that obviates the
AVOID_COMPAT_SENSITIVE case.
next prev parent reply other threads:[~2025-10-27 18:53 UTC|newest]
Thread overview: 75+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-10-01 2:52 [PATCH v2 00/21] Runtime TDX Module update support Chao Gao
2025-10-01 2:52 ` [PATCH v2 01/21] x86/virt/tdx: Print SEAMCALL leaf numbers in decimal Chao Gao
2025-10-01 2:52 ` [PATCH v2 02/21] x86/virt/tdx: Use %# prefix for hex values in SEAMCALL error messages Chao Gao
2025-10-01 2:52 ` [PATCH v2 03/21] x86/virt/tdx: Move low level SEAMCALL helpers out of <asm/tdx.h> Chao Gao
2025-10-01 2:52 ` [PATCH v2 04/21] x86/virt/tdx: Prepare to support P-SEAMLDR SEAMCALLs Chao Gao
2025-10-01 2:52 ` [PATCH v2 05/21] x86/virt/seamldr: Introduce a wrapper for " Chao Gao
2025-10-01 2:52 ` [PATCH v2 06/21] x86/virt/seamldr: Retrieve P-SEAMLDR information Chao Gao
2025-10-01 2:52 ` [PATCH v2 07/21] coco/tdx-host: Expose P-SEAMLDR information via sysfs Chao Gao
2025-10-30 21:54 ` Sagi Shahar
2025-10-30 23:05 ` dan.j.williams
2025-10-31 14:31 ` Sagi Shahar
2025-10-01 2:52 ` [PATCH v2 08/21] coco/tdx-host: Implement FW_UPLOAD sysfs ABI for TDX Module updates Chao Gao
2025-10-01 2:52 ` [PATCH v2 09/21] x86/virt/seamldr: Block TDX Module updates if any CPU is offline Chao Gao
2025-10-01 2:52 ` [PATCH v2 10/21] x86/virt/seamldr: Verify availability of slots for TDX Module updates Chao Gao
2025-10-01 2:52 ` [PATCH v2 11/21] x86/virt/seamldr: Allocate and populate a module update request Chao Gao
2025-10-01 2:52 ` [PATCH v2 12/21] x86/virt/seamldr: Introduce skeleton for TDX Module updates Chao Gao
2025-10-01 2:52 ` [PATCH v2 13/21] x86/virt/seamldr: Abort updates if errors occurred midway Chao Gao
2025-10-01 2:52 ` [PATCH v2 14/21] x86/virt/seamldr: Shut down the current TDX module Chao Gao
2025-10-01 2:52 ` [PATCH v2 15/21] x86/virt/tdx: Reset software states after TDX module shutdown Chao Gao
2025-10-01 2:53 ` [PATCH v2 16/21] x86/virt/seamldr: Handle TDX Module update failures Chao Gao
2025-10-28 2:53 ` Chao Gao
2025-10-01 2:53 ` [PATCH v2 17/21] x86/virt/seamldr: Install a new TDX Module Chao Gao
2025-10-01 2:53 ` [PATCH v2 18/21] x86/virt/seamldr: Do TDX per-CPU initialization after updates Chao Gao
2025-10-01 2:53 ` [PATCH v2 19/21] x86/virt/tdx: Establish contexts for the new TDX Module Chao Gao
2025-10-01 2:53 ` [PATCH v2 20/21] x86/virt/tdx: Update tdx_sysinfo and check features post-update Chao Gao
2025-10-01 2:53 ` [PATCH v2 21/21] x86/virt/tdx: Enable TDX Module runtime updates Chao Gao
2025-10-14 15:32 ` [PATCH v2 00/21] Runtime TDX Module update support Vishal Annapurve
2025-10-15 8:54 ` Reshetova, Elena
2025-10-15 14:19 ` Vishal Annapurve
2025-10-16 6:48 ` Reshetova, Elena
2025-10-15 15:02 ` Dave Hansen
2025-10-16 6:46 ` Reshetova, Elena
2025-10-16 17:47 ` Vishal Annapurve
2025-10-17 10:08 ` Reshetova, Elena
2025-10-18 0:01 ` Vishal Annapurve
2025-10-21 13:42 ` Reshetova, Elena
2025-10-22 7:14 ` Chao Gao
2025-10-22 15:42 ` Vishal Annapurve
2025-10-23 20:31 ` Vishal Annapurve
2025-10-23 21:10 ` Dave Hansen
2025-10-23 22:00 ` Vishal Annapurve
2025-10-24 7:43 ` Chao Gao
2025-10-24 18:02 ` Dave Hansen
2025-10-24 19:40 ` dan.j.williams
2025-10-24 20:00 ` Sean Christopherson
2025-10-24 20:14 ` Dave Hansen
2025-10-24 21:09 ` Vishal Annapurve
2025-10-24 20:13 ` Dave Hansen
2025-10-24 21:12 ` dan.j.williams
2025-10-24 21:19 ` Dave Hansen
2025-10-25 0:54 ` Vishal Annapurve
2025-10-25 1:42 ` dan.j.williams
2025-10-25 11:55 ` Vishal Annapurve
2025-10-25 12:01 ` Vishal Annapurve
2025-10-26 21:30 ` dan.j.williams
2025-10-26 22:01 ` Vishal Annapurve
2025-10-27 18:53 ` dan.j.williams [this message]
2025-10-28 0:42 ` Vishal Annapurve
2025-10-28 2:13 ` dan.j.williams
2025-10-28 17:00 ` Erdem Aktas
2025-10-29 0:56 ` Sean Christopherson
2025-10-29 2:17 ` dan.j.williams
2025-10-29 13:48 ` Sean Christopherson
2025-10-30 17:01 ` Vishal Annapurve
2025-10-31 2:53 ` Chao Gao
2025-11-19 22:44 ` Sagi Shahar
2025-11-20 2:47 ` Chao Gao
2025-10-28 23:48 ` Vishal Annapurve
2025-10-28 20:29 ` dan.j.williams
2025-10-28 20:32 ` dan.j.williams
2025-10-31 16:55 ` Sagi Shahar
2025-10-31 17:57 ` Vishal Annapurve
2025-11-01 2:18 ` Chao Gao
2025-11-01 2:05 ` Chao Gao
2025-11-12 14:09 ` Chao Gao
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