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

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Message-ID: <CAAhR5DF1=iOMFXLsnYjgh2hxYPLLACAt3eUFciwDadeMDv4Kkg@mail.gmail.com>
Date: Thu, 20 Nov 2025 17:38:52 -0600
From: Sagi Shahar <sagis@...gle.com>
To: Chao Gao <chao.gao@...el.com>
Cc: Vishal Annapurve <vannapurve@...gle.com>, Sean Christopherson <seanjc@...gle.com>, dan.j.williams@...el.com, 
	Erdem Aktas <erdemaktas@...gle.com>, Dave Hansen <dave.hansen@...el.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>, 
	"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 Wed, Nov 19, 2025 at 8:47 PM Chao Gao <chao.gao@...el.com> wrote:
>
> On Wed, Nov 19, 2025 at 04:44:50PM -0600, Sagi Shahar wrote:
> >On Thu, Oct 30, 2025 at 9:53 PM Chao Gao <chao.gao@...el.com> wrote:
> >>
> >> >A reference patch we tested for "Avoid updates during update-sensitive
> >> >times" and one caveat was that
> >> >/sys/devices/virtual/tdx/tdx_tsm/version was not available post update
> >> >failure until a subsequent successful update:
> >>
> >> I also tested this. It works well to prevent updates during TD build, so,
> >>
> >>   Tested-by: Chao Gao <chao.gao@...el.com>
> >>
> >> And I can integrate this change into my next version if you don't object.
> >>
> >> Regarding the caveat, could you check if the diff [*] I posted earlier this
> >> week can fix it?
> >>
> >> [1]: https://lore.kernel.org/linux-coco/aQAwRrvYMcaMsu02@intel.com/
> >
> >[Now in plaintext]
> >
> >I tried testing it with the 1.5.24 TDX module and it sometimes fails,
> >but the failure does not appear consistent.
> >
> >I added a local change to add the
> >TDX_SYS_SHUTDOWN_AVOID_COMPAT_SENSITIVE flag when calling
> >TDH_SYS_SHUTDOWN and TDH_SYS_SHUTDOWN fails as expected if a VM is
> >under build:
> >[ 1224.571177] virt/tdx: SEAMCALL (52) failed: 0x8000051200010000
> >
> >But then sometimes trying to finalize the VM fail with the following error:
> >[ 1230.915145] kvm_intel: SEAMCALL TDH_MR_FINALIZE failed: 0x8000ff00ffff0000
> >[ 1230.948264] kvm_intel: tdh_mng_vpflushdone() failed. HKID 3 is leaked.
> >
> >At this point the module seems to be in a broken state and trying to
> >create more TDs will fail:
> >[ 1543.745606] kvm_intel: SEAMCALL TDH_MNG_CREATE failed: 0x8000ff00ffff0000
> >
> >Trying to update the module will fail shutdown with -ENODEV
>
> Can you apply this incremental change to see if the issue gets fixed?
>
> diff --git a/arch/x86/virt/vmx/tdx/seamldr.c b/arch/x86/virt/vmx/tdx/seamldr.c
> index e525bbd16610..f0bea1fecc52 100644
> --- a/arch/x86/virt/vmx/tdx/seamldr.c
> +++ b/arch/x86/virt/vmx/tdx/seamldr.c
> @@ -317,8 +317,9 @@ static int do_seamldr_install_module(void *params)
>                                         tdx_module_set_error();
>                                         print_update_failure_message();
>                                 }
> +                       } else {
> +                               ack_state();
>                         }
> -                       ack_state();
>                 } else {
>                         touch_nmi_watchdog();
>                         rcu_momentary_eqs();
>
>
> The problem is if the failing CPU is the last one to ack the TDP_SHUTDOWN
> state, the state will move to TDP_CPU_INSTALL state. Other CPUs may proceed to
> install the new module before seeing tdp_data.failed. This disables TDX ISA, so
> any subsequent SEAMCALLs get 0x8000ff00ffff0000.

Thanks, I ran a couple dozen updates while TD was being built and
couldn't reproduce the issue with the new fix