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Date: Thu, 21 Mar 2024 10:58:08 +1300
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Subject: Re: [PATCH v2 2/5] x86/kexec: do unconditional WBINVD in
 relocate_kernel()
Content-Language: en-US
To: Tom Lendacky <thomas.lendacky@amd.com>, "Kirill A. Shutemov"
	<kirill.shutemov@linux.intel.com>
CC: <linux-kernel@vger.kernel.org>, <x86@kernel.org>, <dave.hansen@intel.com>,
	<bp@alien8.de>, <tglx@linutronix.de>, <mingo@redhat.com>, <hpa@zytor.com>,
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	<ashish.kalra@amd.com>, <chao.gao@intel.com>, <bhe@redhat.com>,
	<nik.borisov@suse.com>, <pbonzini@redhat.com>, <seanjc@google.com>
References: <cover.1710811610.git.kai.huang@intel.com>
 <e1d37efb8951eb1d38493687b10a21b23353e35a.1710811610.git.kai.huang@intel.com>
 <tvembdwwh4immxytlfzlhpvd42dlfsz7sddb7msk23kdduhu3t@ogpc66hklorv>
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 <689bbd29-aaf0-452e-a97f-41b8e3aa6224@intel.com>
 <5a2441a3-4d7e-4fee-bfa7-65b53376b0ab@amd.com>
 <e677ab03-8b25-46cd-90ac-cacae6ba5027@intel.com>
 <af42b662-1183-4968-807c-96b37166d316@amd.com>
From: "Huang, Kai" <kai.huang@intel.com>
In-Reply-To: <af42b662-1183-4968-807c-96b37166d316@amd.com>
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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.