RE: [PATCH v2 1/4] hyperv: Introduce new hypercall interfaces used by Hyper-V guest IOMMU

From: Yu Zhang <[email protected]> Sent: Thursday, July 2, 2026 9:05 AM
> 
> From: Wei Liu <[email protected]>
> 
> Hyper-V guest IOMMU is a para-virtualized IOMMU based on hypercalls.
> Introduce the hypercalls used by the child partition to interact with
> this facility.
> 
> These hypercalls fall into below categories:
> - Detection and capability: HVCALL_GET_IOMMU_CAPABILITIES is used to
>   detect the existence and capabilities of the guest IOMMU.
> 
> - Device management: HVCALL_GET_LOGICAL_DEVICE_PROPERTY is used to
>   check whether an endpoint device is managed by the guest IOMMU.
> 
> - Domain management: A set of hypercalls is provided to handle the
>   creation, configuration, and deletion of guest domains, as well as
>   the attachment/detachment of endpoint devices to/from those domains.
> 
> - IOTLB flushing: HVCALL_FLUSH_DEVICE_DOMAIN is used to ask Hyper-V
>   for a domain-selective IOTLB flush (which in its handler may flush
>   the device TLB as well).
> 
> Signed-off-by: Wei Liu <[email protected]>
> Co-developed-by: Easwar Hariharan <[email protected]>
> Signed-off-by: Easwar Hariharan <[email protected]>
> Co-developed-by: Yu Zhang <[email protected]>
> Signed-off-by: Yu Zhang <[email protected]>
> ---
>  include/hyperv/hvgdk_mini.h |   8 +++
>  include/hyperv/hvhdk_mini.h | 124 ++++++++++++++++++++++++++++++++++++
>  2 files changed, 132 insertions(+)
> 
> diff --git a/include/hyperv/hvgdk_mini.h b/include/hyperv/hvgdk_mini.h
> index 6a4e8b9d570f..5bdbb44da112 100644
> --- a/include/hyperv/hvgdk_mini.h
> +++ b/include/hyperv/hvgdk_mini.h
> @@ -486,10 +486,16 @@ 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_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_CONFIGURE_DEVICE_DOMAIN			0x00ce
> +#define HVCALL_FLUSH_DEVICE_DOMAIN			0x00d0
>  #define HVCALL_ACQUIRE_SPARSE_SPA_PAGE_HOST_ACCESS	0x00d7
>  #define HVCALL_RELEASE_SPARSE_SPA_PAGE_HOST_ACCESS	0x00d8
>  #define HVCALL_MODIFY_SPARSE_GPA_PAGE_HOST_VISIBILITY	0x00db
> @@ -502,6 +508,8 @@ 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_GET_LOGICAL_DEVICE_PROPERTY		0x0127
>  #define HVCALL_MAP_STATS_PAGE2				0x0131
> 
>  /* HV_HYPERCALL_INPUT */
> diff --git a/include/hyperv/hvhdk_mini.h b/include/hyperv/hvhdk_mini.h
> index b4cb2fa26e9b..493608e791b4 100644
> --- a/include/hyperv/hvhdk_mini.h
> +++ b/include/hyperv/hvhdk_mini.h
> @@ -547,4 +547,128 @@ union hv_device_id {		/* HV_DEVICE_ID */
>  	} acpi;
>  } __packed;
> 
> +/* Device domain types */
> +#define HV_DEVICE_DOMAIN_TYPE_S1	1 /* Stage 1 domain */
> +
> +/* ID for default domain and NULL domain */
> +#define HV_DEVICE_DOMAIN_ID_DEFAULT 0
> +#define HV_DEVICE_DOMAIN_ID_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 {
> +	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 {
> +	u32 as_uint32;
> +	struct {
> +		u32 forward_progress_required: 1;
> +		u32 inherit_owning_vtl: 1;
> +		u32 reserved: 30;
> +	} __packed;
> +};
> +
> +struct 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 {
> +	struct hv_input_device_domain device_domain;
> +} __packed;
> +
> +struct 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 {
> +	u64 partition_id;
> +	union hv_device_id device_id;
> +} __packed;
> +
> +struct hv_device_domain_settings {
> +	struct {
> +		/*
> +		 * Enable translations. If not enabled, all transaction bypass
> +		 * S1 translations.
> +		 */
> +		u64 translation_enabled: 1;
> +		u64 blocked: 1;
> +		/*
> +		 * First stage address translation paging mode:
> +		 * 0: 4-level paging (default)
> +		 * 1: 5-level paging
> +		 */
> +		u64 first_stage_paging_mode: 1;
> +		u64 reserved: 61;
> +	} flags;
> +
> +	/* Address of translation table */
> +	u64 page_table_root;
> +} __packed;
> +
> +struct hv_input_configure_device_domain {
> +	struct hv_input_device_domain device_domain;
> +	struct hv_device_domain_settings settings;
> +} __packed;
> +
> +struct hv_input_get_iommu_capabilities {
> +	u64 partition_id;
> +	u64 reserved;
> +} __packed;
> +
> +struct hv_output_get_iommu_capabilities {
> +	u32 size;
> +	u16 reserved;
> +	u8  max_iova_width;
> +	u8  max_pasid_width;
> +
> +#define HV_IOMMU_CAP_PRESENT (1ULL << 0)
> +#define HV_IOMMU_CAP_S2 (1ULL << 1)
> +#define HV_IOMMU_CAP_S1 (1ULL << 2)
> +#define HV_IOMMU_CAP_S1_5LVL (1ULL << 3)
> +#define HV_IOMMU_CAP_PASID (1ULL << 4)
> +#define HV_IOMMU_CAP_ATS (1ULL << 5)
> +#define HV_IOMMU_CAP_PRI (1ULL << 6)

hvgdk_mini.h mostly uses the Linux BIT() and BIT_ULL()
macros instead of explicit shifts. But this is hvhdk_mini.h.
Does it need to play by a different set of rules for
compatibility with the original Windows files? I think
the Linux BIT* macros are preferable if possible. 

> +
> +	u64 iommu_cap;
> +	u64 pgsize_bitmap;
> +} __packed;
> +
> +enum hv_logical_device_property_code {
> +	HV_LOGICAL_DEVICE_PROPERTY_PVIOMMU = 10,
> +};
> +
> +struct hv_input_get_logical_device_property {
> +	u64 partition_id;
> +	u64 logical_device_id;
> +	/* Takes values from enum hv_logical_device_property_code. */
> +	u32 code;
> +	u32 reserved;
> +} __packed;
> +
> +struct hv_output_get_logical_device_property {
> +#define HV_DEVICE_IOMMU_ENABLED (1ULL << 0)

Same here about BIT_ULL().

> +	u64 device_iommu;
> +	u64 reserved;
> +} __packed;
> +
> +struct hv_input_flush_device_domain {
> +	struct hv_input_device_domain device_domain;
> +	u32 flags;
> +	u32 reserved;
> +} __packed;
> +
>  #endif /* _HV_HVHDK_MINI_H */
> --
> 2.52.0
>