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Subject: Re: [RFC PATCH V3 01/11] x86/HV: Initialize GHCB page in Isolation VM
To:     Joerg Roedel <joro@8bytes.org>
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References: <20210530150628.2063957-1-ltykernel@gmail.com>
 <20210530150628.2063957-2-ltykernel@gmail.com> <YMC2RSr/J1WYCvtz@8bytes.org>
From:   Tianyu Lan <ltykernel@gmail.com>
Message-ID: <c9a7eaa8-a8b3-3ed3-c52c-7a2cea3c95bc@gmail.com>
Date:   Thu, 10 Jun 2021 22:13:32 +0800
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Hi Joerg：
	Thanks for your review.


On 6/9/2021 8:38 PM, Joerg Roedel wrote:
> On Sun, May 30, 2021 at 11:06:18AM -0400, Tianyu Lan wrote:
>> From: Tianyu Lan <Tianyu.Lan@microsoft.com>
>>
>> Hyper-V exposes GHCB page via SEV ES GHCB MSR for SNP guest
>> to communicate with hypervisor. Map GHCB page for all
>> cpus to read/write MSR register and submit hvcall request
>> via GHCB.
>>
>> Signed-off-by: Tianyu Lan <Tianyu.Lan@microsoft.com>
>> ---
>>   arch/x86/hyperv/hv_init.c       | 60 ++++++++++++++++++++++++++++++---
>>   arch/x86/include/asm/mshyperv.h |  2 ++
>>   include/asm-generic/mshyperv.h  |  2 ++
>>   3 files changed, 60 insertions(+), 4 deletions(-)
>>
>> diff --git a/arch/x86/hyperv/hv_init.c b/arch/x86/hyperv/hv_init.c
>> index bb0ae4b5c00f..dc74d01cb859 100644
>> --- a/arch/x86/hyperv/hv_init.c
>> +++ b/arch/x86/hyperv/hv_init.c
>> @@ -60,6 +60,9 @@ static int hv_cpu_init(unsigned int cpu)
>>   	struct hv_vp_assist_page **hvp = &hv_vp_assist_page[smp_processor_id()];
>>   	void **input_arg;
>>   	struct page *pg;
>> +	u64 ghcb_gpa;
>> +	void *ghcb_va;
>> +	void **ghcb_base;
> 
> Any reason you can't reuse the SEV-ES support code in the Linux kernel?
> It already has code to setup GHCBs for all vCPUs.
> 
> I see that you don't need #VC handling in your SNP VMs because of the
> paravisor running underneath it, but just re-using the GHCB setup code
> shouldn't be too hard.
> 

Thanks for your suggestion. I will have a try to use SEV-ES code.