Re: [RFC v1 3/5] hyperv: Introduce new hypercall interfaces used by Hyper-V guest IOMMU

Tianyu Lan
2026-04-16T03:30:35Z

On Tue, Dec 9, 2025 at 1:13 PM Yu Zhang <zhangyu1@linux.microsoft.com> wrote:
>
> From: Wei Liu <wei.liu@kernel.org>
>
> 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). Page-selective IOTLB flushes will be offered
> by new hypercalls in future patches.
>
> Signed-off-by: Wei Liu <wei.liu@kernel.org>
> Co-developed-by: Jacob Pan <jacob.pan@linux.microsoft.com>
> Signed-off-by: Jacob Pan <jacob.pan@linux.microsoft.com>
> Co-developed-by: Easwar Hariharan <easwar.hariharan@linux.microsoft.com>
> Signed-off-by: Easwar Hariharan <easwar.hariharan@linux.microsoft.com>
> Co-developed-by: Yu Zhang <zhangyu1@linux.microsoft.com>
> Signed-off-by: Yu Zhang <zhangyu1@linux.microsoft.com>
> ---
> include/hyperv/hvgdk_mini.h | 8 +++
> include/hyperv/hvhdk_mini.h | 123 ++++++++++++++++++++++++++++++++++++
> 2 files changed, 131 insertions(+)
>
> diff --git a/include/hyperv/hvgdk_mini.h b/include/hyperv/hvgdk_mini.h
> index 77abddfc750e..e5b302bbfe14 100644
> --- a/include/hyperv/hvgdk_mini.h
> +++ b/include/hyperv/hvgdk_mini.h
> @@ -478,10 +478,16 @@ 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
> @@ -492,6 +498,8 @@ union hv_vp_assist_msr_contents { /* HV_REGISTER_VP_ASSIST_PAGE */
> #define HVCALL_GET_VP_CPUID_VALUES 0x00f4
> #define HVCALL_MMIO_READ 0x0106
> #define HVCALL_MMIO_WRITE 0x0107
> +#define HVCALL_GET_IOMMU_CAPABILITIES 0x0125
> +#define HVCALL_GET_LOGICAL_DEVICE_PROPERTY 0x0127
>
> /* HV_HYPERCALL_INPUT */
> #define HV_HYPERCALL_RESULT_MASK GENMASK_ULL(15, 0)
> diff --git a/include/hyperv/hvhdk_mini.h b/include/hyperv/hvhdk_mini.h
> index 858f6a3925b3..ba6b91746b13 100644
> --- a/include/hyperv/hvhdk_mini.h
> +++ b/include/hyperv/hvhdk_mini.h
> @@ -400,4 +400,127 @@ 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)
> +
> + 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;
> + enum hv_logical_device_property_code code;
> + u32 reserved;
> +} __packed;
> +
> +struct hv_output_get_logical_device_property {
> +#define HV_DEVICE_IOMMU_ENABLED (1ULL << 0)
> + 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 */
> --
> 2.49.0
>
>

No code uses these definitions in this patch and it's better to merge
with Patch 5?
--
Thanks
Tianyu Lan