linux-kernel - Re: [PATCH v2 2/5] x86/kexec: do unconditional WBINVD in relocate

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Date: Thu, 21 Mar 2024 10:58:08 +1300
From: "Huang, Kai" <kai.huang@...el.com>
To: Tom Lendacky <thomas.lendacky@....com>, "Kirill A. Shutemov"
	<kirill.shutemov@...ux.intel.com>
CC: <linux-kernel@...r.kernel.org>, <x86@...nel.org>, <dave.hansen@...el.com>,
	<bp@...en8.de>, <tglx@...utronix.de>, <mingo@...hat.com>, <hpa@...or.com>,
	<luto@...nel.org>, <peterz@...radead.org>, <rick.p.edgecombe@...el.com>,
	<ashish.kalra@....com>, <chao.gao@...el.com>, <bhe@...hat.com>,
	<nik.borisov@...e.com>, <pbonzini@...hat.com>, <seanjc@...gle.com>
Subject: Re: [PATCH v2 2/5] x86/kexec: do unconditional WBINVD in
 relocate_kernel()



On 21/03/2024 10:06 am, Tom Lendacky wrote:
> On 3/20/24 15:48, Huang, Kai wrote:
>>
>>>> Hi Tom,
>>>>
>>>> I am not aware of kexec() support status for SEV-ES/SEV-SNP guests. 
>>>> Does patch 1 break them?
>>>
>>> SNP guests can kexec with some patches that are currently in process 
>>> around shared to private memory conversions. ES guests can only kexec 
>>> with a single vCPU. There was a recent patch series to add support 
>>> for multiple vCPUs.
>>>
>>> Patch #1 doesn't break either ES or SNP because we still have an IDT 
>>> and traditional kernel addressing in place, so the #VC can be handled.
>>
>> How about plain SEV guest?
> 
> A plain SEV guest is fine, since WBINVD is intercepted and would just 
> exit to the hypervisor (#VC doesn't happen with plain SEV).
> 
> Thanks,
> Tom
> 

Thanks for the info.