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Message-ID: <693ff56a-9870-9eb0-c4c8-84b4451667cd@gmail.com>
Date:   Tue, 6 Jun 2023 21:43:29 +0800
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Subject: Re: [PATCH 1/9] x86/hyperv: Add sev-snp enlightened guest static key
To:     Vitaly Kuznetsov <vkuznets@redhat.com>
Cc:     Tianyu Lan <tiala@microsoft.com>, linux-arch@vger.kernel.org,
        linux-hyperv@vger.kernel.org, linux-kernel@vger.kernel.org,
        kys@microsoft.com, haiyangz@microsoft.com, wei.liu@kernel.org,
        decui@microsoft.com, tglx@linutronix.de, mingo@redhat.com,
        bp@alien8.de, dave.hansen@linux.intel.com, x86@kernel.org,
        hpa@zytor.com, daniel.lezcano@linaro.org, arnd@arndb.de,
        michael.h.kelley@microsoft.com
References: <20230601151624.1757616-1-ltykernel@gmail.com>
 <20230601151624.1757616-2-ltykernel@gmail.com> <874jnmkt4p.fsf@redhat.com>
From:   Tianyu Lan <ltykernel@gmail.com>
In-Reply-To: <874jnmkt4p.fsf@redhat.com>
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On 6/5/2023 8:09 PM, Vitaly Kuznetsov wrote:
>> --- a/arch/x86/kernel/cpu/mshyperv.c
>> +++ b/arch/x86/kernel/cpu/mshyperv.c
>> @@ -402,8 +402,12 @@ static void __init ms_hyperv_init_platform(void)
>>   		pr_info("Hyper-V: Isolation Config: Group A 0x%x, Group B 0x%x\n",
>>   			ms_hyperv.isolation_config_a, ms_hyperv.isolation_config_b);
>>   
>> -		if (hv_get_isolation_type() == HV_ISOLATION_TYPE_SNP)
>> +
>> +		if (cc_platform_has(CC_ATTR_GUEST_SEV_SNP)) {
>> +			static_branch_enable(&isolation_type_en_snp);
>> +		} else if (hv_get_isolation_type() == HV_ISOLATION_TYPE_SNP) {
>>   			static_branch_enable(&isolation_type_snp);
> Nitpick: In case 'isolation_type_snp' and 'isolation_type_en_snp' are
> mutually exclusive, I'd suggest we rename the former: it is quite
> un-intuitive that for an enlightened SNP guest '&isolation_type_snp' is
> NOT enabled. E.g. we can use
> 
> 'isol_type_snp_paravisor'
> and
> 'isol_type_snp_enlightened'
> 
> (I also don't like 'isolation_type_en_snp' name as 'en' normally stands
> for 'enabled')

Hi Vitaly:
	Thanks for your review. Agree. Will rename them.

> 
>> --- a/include/asm-generic/mshyperv.h
>> +++ b/include/asm-generic/mshyperv.h
>> @@ -36,15 +36,21 @@ struct ms_hyperv_info {
>>   	u32 nested_features;
>>   	u32 max_vp_index;
>>   	u32 max_lp_index;
>> -	u32 isolation_config_a;
>> +	union {
>> +		u32 isolation_config_a;
>> +		struct {
>> +			u32 paravisor_present : 1;
>> +			u32 reserved1 : 31;
>> +		};
>> +	};
>>   	union {
>>   		u32 isolation_config_b;
>>   		struct {
>>   			u32 cvm_type : 4;
>> -			u32 reserved1 : 1;
>> +			u32 reserved2 : 1;
>>   			u32 shared_gpa_boundary_active : 1;
>>   			u32 shared_gpa_boundary_bits : 6;
>> -			u32 reserved2 : 20;
>> +			u32 reserved3 : 20;
> Maybe use 'reserved_a1', 'reserved_b1', 'reserved_b2',... to avoid the
> need to rename in the future when more bits from isolation_config_a get
> used?
> 

Good suggestion. will update.