linux-kernel - Re: [RFC PATCH] x86/virt/tdx: Disable KEXEC in the presence of TDX

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Date: Fri, 19 Jan 2024 02:55:33 +0200
From: Nikolay Borisov <nik.borisov@...e.com>
To: "Huang, Kai" <kai.huang@...el.com>,
 "kirill.shutemov@...ux.intel.com" <kirill.shutemov@...ux.intel.com>,
 "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Cc: "linux-coco@...ts.linux.dev" <linux-coco@...ts.linux.dev>,
 "x86@...nel.org" <x86@...nel.org>,
 "dave.hansen@...ux.intel.com" <dave.hansen@...ux.intel.com>
Subject: Re: [RFC PATCH] x86/virt/tdx: Disable KEXEC in the presence of TDX



On 19.01.24 г. 2:52 ч., Huang, Kai wrote:
> On Fri, 2024-01-19 at 02:49 +0200, Nikolay Borisov wrote:
>> [Adding Kirill as he has a series in flight about KEXEC]
>>
>> On 18.01.24 г. 23:31 ч., Huang, Kai wrote:
>>> On Thu, 2024-01-18 at 18:01 +0200, Nikolay Borisov wrote:
>>>> TDX doesn't currently support kexec so disable the latter when TDX
>>>> is detected at boot time. If kexec must absolutely be supported then
>>>> TDX can be disabled from the bios.
>>>>
>>>> Making this decision at run time rather than as a compile time option
>>>> allows distribution kernels to have both enabled and delegate to the
>>>> user whether they want to use TDX/Kexec.
>>>>
>>>> Signed-off-by: Nikolay Borisov <nik.borisov@...e.com>
>>>
>>> Hi Nikolay,
>>>
>>> Thanks for the patch.
>>>
>>> I am working in progress on patches to make kexec() work with TDX.  I plan to
>>> send them out soon (e.g., next week), but I think perhaps your patch is
>>> reasonable before that is merged.
>>
>> I thought Kirill's series rectifies this ?
>>
> 
> No that's for TDX guest.

Well in this case shouldn't INTEL_TDX_GUEST also be gated on KEXEC_CORE 
being inoperable either via Kconfig option or via a similar approach to 
this one (if it's accepted)?