Re: [PATCH V0 2/3] mshv: Import data structs around device domains from hyperv headers

[Mukesh R <mrathor@linux.microsoft.com>]

On 9/22/26 10:48, Easwar Hariharan wrote:
> On 9/21/2026 15:50, Mukesh R wrote:
>> Copy/import from Hyper-V public headers, definitions and declarations that
>> are related to creating iommu domains in the hypervisor, attaching devices
>> to them, doing the reverse, etc.
>>
>> Signed-off-by: Mukesh R <mrathor@linux.microsoft.com>
>> ---
>>   include/hyperv/hvgdk_mini.h |  9 ++++
>>   include/hyperv/hvhdk_mini.h | 90 +++++++++++++++++++++++++++++++++++++
>>   2 files changed, 99 insertions(+)
>>
>> diff --git a/include/hyperv/hvgdk_mini.h b/include/hyperv/hvgdk_mini.h
>> index 6a4e8b9d570f..3b74f3c0229d 100644
>> --- a/include/hyperv/hvgdk_mini.h
>> +++ b/include/hyperv/hvgdk_mini.h
>> @@ -326,6 +326,8 @@ union hv_hypervisor_version_info {
>>   /* stimer Direct Mode is available */
>>   #define HV_STIMER_DIRECT_MODE_AVAILABLE			BIT(19)
>>   
>> +#define HV_DEVICE_DOMAIN_AVAILABLE			BIT(24)
>> +
> 
> For my understanding, how is ms_hyperv.misc_features.HV_DEVICE_DOMAIN_AVAILABLE = 1
> different from HV_IOMMU_CAP_PRESENT = 1 combined with HV_IOMMU_CAP_S2 = 1?
> It seems like there is room to combine forces with the guest driver and just go with
> the latter.

It's different. we want to make sure the version of the hypervisor
supports creating device domains. see: HVCALL_CREATE_DEVICE_DOMAIN

Thanks,
-Mukesh

>>   /*
>>    * Implementation recommendations. Indicates which behaviors the hypervisor
>>    * recommends the OS implement for optimal performance.
>> @@ -486,9 +488,15 @@ union hv_vp_assist_msr_contents {	 /* HV_REGISTER_VP_ASSIST_PAGE */
>>   #define HVCALL_GET_VP_INDEX_FROM_APIC_ID		0x009a
>>   #define HVCALL_FLUSH_GUEST_PHYSICAL_ADDRESS_SPACE	0x00af
>>   #define HVCALL_FLUSH_GUEST_PHYSICAL_ADDRESS_LIST	0x00b0
>> +#define HVCALL_CREATE_DEVICE_DOMAIN                     0x00b1
>> +#define HVCALL_ATTACH_DEVICE_DOMAIN                     0x00b2
>> +#define HVCALL_MAP_DEVICE_GPA_PAGES                     0x00b3
>> +#define HVCALL_UNMAP_DEVICE_GPA_PAGES                   0x00b4
>>   #define HVCALL_SIGNAL_EVENT_DIRECT			0x00c0
>>   #define HVCALL_POST_MESSAGE_DIRECT			0x00c1
>>   #define HVCALL_DISPATCH_VP				0x00c2
>> +#define HVCALL_DETACH_DEVICE_DOMAIN                     0x00c4
>> +#define HVCALL_DELETE_DEVICE_DOMAIN                     0x00c5
>>   #define HVCALL_GET_GPA_PAGES_ACCESS_STATES		0x00c9
>>   #define HVCALL_ACQUIRE_SPARSE_SPA_PAGE_HOST_ACCESS	0x00d7
>>   #define HVCALL_RELEASE_SPARSE_SPA_PAGE_HOST_ACCESS	0x00d8
>> @@ -502,6 +510,7 @@ union hv_vp_assist_msr_contents {	 /* HV_REGISTER_VP_ASSIST_PAGE */
>>   #define HVCALL_MMIO_READ				0x0106
>>   #define HVCALL_MMIO_WRITE				0x0107
>>   #define HVCALL_DISABLE_HYP_EX                           0x010f
>> +#define HVCALL_GET_IOMMU_CAPABILITIES			0x0125
>>   #define HVCALL_MAP_STATS_PAGE2				0x0131
>>   
>>   /* HV_HYPERCALL_INPUT */
>> diff --git a/include/hyperv/hvhdk_mini.h b/include/hyperv/hvhdk_mini.h
>> index 035ba20870f7..3bb052fd6e06 100644
>> --- a/include/hyperv/hvhdk_mini.h
>> +++ b/include/hyperv/hvhdk_mini.h
>> @@ -548,4 +548,94 @@ union hv_device_id {		/* HV_DEVICE_ID */
>>   	} acpi;
>>   } __packed;
>>   
>> +/* 3 domain types: stage 1, stage 2, and SOC */
>> +#define HV_DEVICE_DOMAIN_TYPE_S2  0 /* HV_DEVICE_DOMAIN_ID_TYPE_S2 */
>> +#define HV_DEVICE_DOMAIN_TYPE_S1  1 /* HV_DEVICE_DOMAIN_ID_TYPE_S1 */
> 
> 
>> +#define HV_DEVICE_DOMAIN_TYPE_SOC 2 /* HV_DEVICE_DOMAIN_ID_TYPE_SOC */
> 
> I don't think this domain type is used in patch 3, perhaps we bring it in when needed?
> 
>> +
>> +/* ID for stage 2 default domain and NULL domain */
> 
> I think this comment would be more useful if it related the MSHV default and NULL domains to
> the Linux equivalents of identity and blocking respectively. As it stands, it just repeats the
> names of the defines it is a comment for.
> 
>> +#define HV_DEVICE_DOMAIN_ID_S2_DEFAULT 0
>> +#define HV_DEVICE_DOMAIN_ID_S2_NULL    0xFFFFFFFFULL
>> +
>> +union hv_device_domain_id {
>> +	u64 as_uint64;
>> +	struct {
>> +		u32 type : 4;
>> +		u32 reserved : 28;
>> +		u32 id;
>> +	};
>> +} __packed;
>> +
>> +struct hv_input_device_domain { /* HV_INPUT_DEVICE_DOMAIN */
>> +	u64 partition_id;
>> +	union hv_input_vtl owner_vtl;
>> +	u8 padding[7];
>> +	union hv_device_domain_id domain_id;
>> +} __packed;
>> +
>> +union hv_create_device_domain_flags {	/* HV_CREATE_DEVICE_DOMAIN_FLAGS */
>> +	u32 as_uint32;
>> +	struct {
>> +		u32 forward_progress_required : 1;
>> +		u32 inherit_owning_vtl : 1;
>> +		u32 reserved : 30;
>> +	} __packed;
>> +} __packed;
>> +
>> +struct hv_input_create_device_domain {	/* HV_INPUT_CREATE_DEVICE_DOMAIN */
>> +	struct hv_input_device_domain device_domain;
>> +	union hv_create_device_domain_flags create_device_domain_flags;
>> +} __packed;
>> +
>> +struct hv_input_delete_device_domain {	/* HV_INPUT_DELETE_DEVICE_DOMAIN */
>> +	struct hv_input_device_domain device_domain;
>> +} __packed;
>> +
>> +struct hv_input_attach_device_domain {	/* HV_INPUT_ATTACH_DEVICE_DOMAIN */
>> +	struct hv_input_device_domain device_domain;
>> +	union hv_device_id device_id;
>> +} __packed;
>> +
>> +struct hv_input_detach_device_domain {	/* HV_INPUT_DETACH_DEVICE_DOMAIN */
>> +	u64 partition_id;
>> +	union hv_device_id device_id;
>> +} __packed;
>> +
>> +/* HV_INPUT_GET_IOMMU_CAPABILITIES */
>> +struct hv_input_get_iommu_capabilities {
>> +	u64 partition_id;
>> +	u64 reserved;
>> +} __packed;
>> +
>> +#define HV_IOMMU_CAP_PRESENT    BIT_ULL(0)
>> +#define HV_IOMMU_CAP_S2         BIT_ULL(1)
>> +#define HV_IOMMU_CAP_S1         BIT_ULL(2)
>> +#define HV_IOMMU_CAP_S1_5LVL    BIT_ULL(3)
>> +#define HV_IOMMU_CAP_PASID      BIT_ULL(4)
>> +#define HV_IOMMU_CAP_ATS        BIT_ULL(5)
>> +#define HV_IOMMU_CAP_PRI        BIT_ULL(6)
>> +
>> +struct hv_output_get_iommu_capabilities { /* HV_OUTPUT_GET_IOMMU_CAPABILITIES */
>> +	u32 size;
>> +	u16 reserved;
>> +	u8  max_iova_width;
>> +	u8  max_pasid_width;
>> +	u64 iommu_cap;          /* HV_IOMMU_CAP_* above */
>> +	u64 pgsize_bitmap;
>> +} __packed;
>> +
>> +struct hv_input_map_device_gpa_pages {	/* HV_INPUT_MAP_DEVICE_GPA_PAGES */
>> +	struct hv_input_device_domain device_domain;
>> +	union hv_input_vtl target_vtl;
>> +	u8 padding[3];
>> +	u32 map_flags;
>> +	u64 target_device_va_base;
>> +	u64 gpa_page_list[];
>> +} __packed;
>> +
>> +struct hv_input_unmap_device_gpa_pages {  /* HV_INPUT_UNMAP_DEVICE_GPA_PAGES */
>> +	struct hv_input_device_domain device_domain;
>> +	u64 target_device_va_base;
>> +} __packed;
>> +
>>   #endif /* _HV_HVHDK_MINI_H */