Re: [PATCH v5 12/22] x86/virt/tdx: Reset software states during TDX module shutdown

["Huang, Kai" <kai.huang@intel.com>]

On Tue, 2026-03-17 at 16:27 +0800, Gao, Chao wrote:
> On Mon, Mar 16, 2026 at 05:06:49PM +0800, Huang, Kai wrote:
> > 
> > > @@ -1179,6 +1179,7 @@ EXPORT_SYMBOL_FOR_KVM(tdx_enable);
> > >  int tdx_module_shutdown(void)
> > >  {
> > >  	struct tdx_module_args args = {};
> > > +	int ret, cpu;
> > >  
> > >  	/*
> > >  	 * Shut down the TDX module and prepare handoff data for the next
> > > @@ -1188,7 +1189,22 @@ int tdx_module_shutdown(void)
> > >  	 * modules as new modules likely have higher handoff version.
> > >  	 */
> > >  	args.rcx = tdx_sysinfo.handoff.module_hv;
> > > -	return seamcall_prerr(TDH_SYS_SHUTDOWN, &args);
> > > +	ret = seamcall_prerr(TDH_SYS_SHUTDOWN, &args);
> > > +	if (ret)
> > > +		return ret;
> > > +
> > > +	tdx_module_status = TDX_MODULE_UNINITIALIZED;
> > > +	sysinit_done = false;
> > > +	sysinit_ret = 0;
> > > +
> > > +	/*
> > > +	 * By reaching here CPUHP is disabled and all present CPUs
> > > +	 * are online. It's safe to just loop all online CPUs and
> > > +	 * reset the per-cpu flag.
> > > +	 */
> > > +	for_each_online_cpu(cpu)
> > > +		per_cpu(tdx_lp_initialized, cpu) = false;
> > 
> > Since you have removed the requirement that P-SEAMLDR.INSTALL must be done
> > on all CPUs, and removed the relevant patch, the "all present CPUs are
> > online" part isn't correct anymore.
> > 
> > And using for_each_online_cpu() isn't enough since this doesn't reset the
> > tdx_lp_initialized for offline CPUs.
> > 
> > One way is to just use for_each_possible_cpu() here so tdx_lp_initialized
> > for all CPUs are reset.  Since the "CPUHP is disabled" part is still correct
> > AFAICT (since stop_machine() disables CPUHP internally during the
> > operation), resetting tdx_lp_initialized for offline CPUs won't race with
> > CPUHP.
> > 
> > And assuming this series will be applied after Sean's VMXON series, we will
> 
> Yes.
> 
> > have a TDX-specific CPUHP callback tdx_online_cpu() in TDX x86 core to do
> > tdx_cpu_enable(), which will then enable TDX again on the new-online CPU.
> 
> Good point.
> 
> Clearing tdx_lp_initialized for offlined CPUs makes sense, but I'd rather not
> justify this through "enabling TDX on new-online CPUs" since many details
> remain unclear. For example, there will be a SEAMCALL to disable TDX per-CPU.

Sorry which SEAMCALL are you referring to?

> It should be called when CPUs go offline so that those CPUs can be exempting
> from doing SEAMLDR.INSTALL during module updates. tdx_lp_initialized should
> have been cleared along with that "disable TDX per-CPU" SEAMCALL for offlined
> CPUs.

Hmm.. It sounds like we are missing some background here.  Could you
elaborate what are the steps to update module on a subset of CPUs?