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Subject: Re: [RFC PATCH V3 03/11] x86/Hyper-V: Add new hvcall guest address
 host visibility support
To:     Vitaly Kuznetsov <vkuznets@redhat.com>, kys@microsoft.com,
        haiyangz@microsoft.com, sthemmin@microsoft.com, wei.liu@kernel.org,
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References: <20210530150628.2063957-1-ltykernel@gmail.com>
 <20210530150628.2063957-4-ltykernel@gmail.com>
 <878s3iyrtg.fsf@vitty.brq.redhat.com>
From:   Tianyu Lan <ltykernel@gmail.com>
Message-ID: <2a0170a9-e4d5-1c63-7901-416094f6ab64@gmail.com>
Date:   Thu, 10 Jun 2021 22:18:45 +0800
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Hi Vitaly:
	Thanks for your review.

On 6/10/2021 5:47 PM, Vitaly Kuznetsov wrote:
>> diff --git a/arch/x86/include/asm/hyperv-tlfs.h b/arch/x86/include/asm/hyperv-tlfs.h
>> index 606f5cc579b2..632281b91b44 100644
>> --- a/arch/x86/include/asm/hyperv-tlfs.h
>> +++ b/arch/x86/include/asm/hyperv-tlfs.h
>> @@ -262,6 +262,17 @@ enum hv_isolation_type {
>>   #define HV_X64_MSR_TIME_REF_COUNT	HV_REGISTER_TIME_REF_COUNT
>>   #define HV_X64_MSR_REFERENCE_TSC	HV_REGISTER_REFERENCE_TSC
>>   
>> +/* Hyper-V GPA map flags */
>> +#define HV_MAP_GPA_PERMISSIONS_NONE            0x0
>> +#define HV_MAP_GPA_READABLE                    0x1
>> +#define HV_MAP_GPA_WRITABLE                    0x2
>> +
>> +enum vmbus_page_visibility {
>> +	VMBUS_PAGE_NOT_VISIBLE = 0,
>> +	VMBUS_PAGE_VISIBLE_READ_ONLY = 1,
>> +	VMBUS_PAGE_VISIBLE_READ_WRITE = 3
>> +};
>> +
> Why do we need both flags and the enum? I don't see HV_MAP_GPA_* being
> used anywhere and VMBUS_PAGE_VISIBLE_READ_WRITE looks like
> HV_MAP_GPA_READABLE | HV_MAP_GPA_WRITABLE.
> 
> As this is used to communicate with the host, I'd suggest to avoid using
> enum and just use flags everywhere.
> 

Nice catch. Will update in the next version.

Thanks.