linux-kernel - Re: [PATCH v11 18/20] x86: Handle TDX erratum to reset TDX private memory during kexec() and reboot

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Date:   Wed, 14 Jun 2023 13:02:45 +0300
From:   "kirill.shutemov@...ux.intel.com" <kirill.shutemov@...ux.intel.com>
To:     "Huang, Kai" <kai.huang@...el.com>
Cc:     "kvm@...r.kernel.org" <kvm@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "Hansen, Dave" <dave.hansen@...el.com>,
        "david@...hat.com" <david@...hat.com>,
        "bagasdotme@...il.com" <bagasdotme@...il.com>,
        "ak@...ux.intel.com" <ak@...ux.intel.com>,
        "Wysocki, Rafael J" <rafael.j.wysocki@...el.com>,
        "Chatre, Reinette" <reinette.chatre@...el.com>,
        "Christopherson,, Sean" <seanjc@...gle.com>,
        "pbonzini@...hat.com" <pbonzini@...hat.com>,
        "linux-mm@...ck.org" <linux-mm@...ck.org>,
        "Yamahata, Isaku" <isaku.yamahata@...el.com>,
        "tglx@...utronix.de" <tglx@...utronix.de>,
        "Luck, Tony" <tony.luck@...el.com>,
        "peterz@...radead.org" <peterz@...radead.org>,
        "Shahar, Sagi" <sagis@...gle.com>,
        "imammedo@...hat.com" <imammedo@...hat.com>,
        "Gao, Chao" <chao.gao@...el.com>,
        "Brown, Len" <len.brown@...el.com>,
        "sathyanarayanan.kuppuswamy@...ux.intel.com" 
        <sathyanarayanan.kuppuswamy@...ux.intel.com>,
        "Huang, Ying" <ying.huang@...el.com>,
        "Williams, Dan J" <dan.j.williams@...el.com>
Subject: Re: [PATCH v11 18/20] x86: Handle TDX erratum to reset TDX private
 memory during kexec() and reboot

On Wed, Jun 14, 2023 at 09:33:45AM +0000, Huang, Kai wrote:
> On Mon, 2023-06-05 at 02:27 +1200, Kai Huang wrote:
> > --- a/arch/x86/kernel/reboot.c
> > +++ b/arch/x86/kernel/reboot.c
> > @@ -720,6 +720,7 @@ void native_machine_shutdown(void)
> >  
> >  #ifdef CONFIG_X86_64
> >  	x86_platform.iommu_shutdown();
> > +	x86_platform.memory_shutdown();
> >  #endif
> >  }
> 
> Hi Kirill/Dave,
> 
> I missed that this solution doesn't reset TDX private for emergency restart or
> when reboot_force is set, because machine_shutdown() isn't called for them.
> 
> Is it acceptable?  Or should we handle them too?

Force reboot is not used in kexec path, right? And the platform has to
handle erratum in BIOS to reset memory status on reboot anyway.

I think we should be fine. But it worth mentioning it in the commit
message.

-- 
  Kiryl Shutsemau / Kirill A. Shutemov