linux-kernel - Re: [PATCH v3 2/5] mshv: Add the HVCALL_GET_PARTITION_PROPERTY

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Message-ID: <350e4429-46e5-4011-89c5-85de442e8ddb@linux.microsoft.com>
Date: Fri, 19 Sep 2025 15:30:39 -0700
From: Nuno Das Neves <nunodasneves@...ux.microsoft.com>
To: Stanislav Kinsburskii <skinsburskii@...ux.microsoft.com>
Cc: linux-hyperv@...r.kernel.org, linux-kernel@...r.kernel.org,
 prapal@...ux.microsoft.com, easwar.hariharan@...ux.microsoft.com,
 tiala@...rosoft.com, anirudh@...rudhrb.com,
 paekkaladevi@...ux.microsoft.com, kys@...rosoft.com, haiyangz@...rosoft.com,
 wei.liu@...nel.org, decui@...rosoft.com
Subject: Re: [PATCH v3 2/5] mshv: Add the HVCALL_GET_PARTITION_PROPERTY_EX
 hypercall

On 9/18/2025 11:43 AM, Stanislav Kinsburskii wrote:
> On Tue, Sep 16, 2025 at 04:44:19PM -0700, Nuno Das Neves wrote:
> 
> <snip>
> 
>> diff --git a/include/hyperv/hvhdk.h b/include/hyperv/hvhdk.h
>> index b4067ada02cf..b91358b9c929 100644
>> --- a/include/hyperv/hvhdk.h
>> +++ b/include/hyperv/hvhdk.h
>> @@ -376,6 +376,46 @@ struct hv_input_set_partition_property {
>>  	u64 property_value;
>>  } __packed;
>>  
>> +union hv_partition_property_arg {
>> +	u64 as_uint64;
>> +	struct {
>> +		union {
>> +			u32 arg;
>> +			u32 vp_index;
>> +		};
>> +		u16 reserved0;
>> +		u8 reserved1;
>> +		u8 object_type;
>> +	};
>> +} __packed;
> 
> Shouldn't the struct be "packed" instead?
> 
Indeed, I'll fix it, thanks.

>> +
>> +struct hv_input_get_partition_property_ex {
>> +	u64 partition_id;
>> +	u32 property_code; /* enum hv_partition_property_code */
>> +	u32 padding;
>> +	union {
>> +		union hv_partition_property_arg arg_data;
>> +		u64 arg;
>> +	};
>> +} __packed;
>> +
>> +/*
>> + * NOTE: Should use hv_input_set_partition_property_ex_header to compute this
>> + * size, but hv_input_get_partition_property_ex is identical so it suffices
>> + */
>> +#define HV_PARTITION_PROPERTY_EX_MAX_VAR_SIZE \
>> +	(HV_HYP_PAGE_SIZE - sizeof(struct hv_input_get_partition_property_ex))
>> +
>> +union hv_partition_property_ex {
>> +	u8 buffer[HV_PARTITION_PROPERTY_EX_MAX_VAR_SIZE];
>> +	struct hv_partition_property_vmm_capabilities vmm_capabilities;
>> +	/* More fields to be filled in when needed */
>> +} __packed;
> 
> Packing a union is redundant.
> 
> Thanks,
> Stanislav