linux-kernel - Re: [PATCH] x86: tdx: hide unused tdx_dump_mce

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Message-ID: <a3373c1bb8a1012efbbadd64dc91d81362200e1f.camel@intel.com>
Date:   Wed, 13 Dec 2023 22:32:08 +0000
From:   "Huang, Kai" <kai.huang@...el.com>
To:     "kirill.shutemov@...ux.intel.com" <kirill.shutemov@...ux.intel.com>,
        "Hansen, Dave" <dave.hansen@...el.com>
CC:     "arnd@...nel.org" <arnd@...nel.org>,
        "Yao, Yuan" <yuan.yao@...el.com>, "bp@...en8.de" <bp@...en8.de>,
        "x86@...nel.org" <x86@...nel.org>,
        "dave.hansen@...ux.intel.com" <dave.hansen@...ux.intel.com>,
        "mingo@...hat.com" <mingo@...hat.com>,
        "tglx@...utronix.de" <tglx@...utronix.de>,
        "Luck, Tony" <tony.luck@...el.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "arnd@...db.de" <arnd@...db.de>, "hpa@...or.com" <hpa@...or.com>,
        "Yamahata, Isaku" <isaku.yamahata@...el.com>,
        "linux-coco@...ts.linux.dev" <linux-coco@...ts.linux.dev>
Subject: Re: [PATCH] x86: tdx: hide unused tdx_dump_mce_info()

On Wed, 2023-12-13 at 20:41 +0000, Huang, Kai wrote:
> On Wed, 2023-12-13 at 12:13 -0800, Dave Hansen wrote:
> > On 12/13/23 12:11, Huang, Kai wrote:
> > > > "The machine-check exception handler is expected to be implemented in the
> > > > VMM."
> > > I also agree.  Thanks.
> > 
> > Kai, could you please send a patch to fix this build problem that Arnd
> > reported?
> 
> Turns out INTEL_TDX_GUEST selects X86_MCE, I think we can also just select
> X86_MCE for TDX host?
> 
> config INTEL_TDX_GUEST
>         bool "Intel TDX (Trust Domain Extensions) - Guest Support"
>         depends on X86_64 && CPU_SUP_INTEL
> 	...
>         select X86_MCE
> 	

Turns out we have to use 'depend on' but not 'select' because with the latter I
got "mm/Kconfig:772:error: recursive dependency detected!".

I just sent out the fixing patch.  I did kernel built of multiple combinations
of TDX_GUEST/TDX_HOST/X86_MCE in the Kconfig, and they all passed.