* [PATCH v1 0/4] Hyper-V: Add para-virtualized IOMMU support for Linux guests
@ 2026-05-11 16:24 Yu Zhang
2026-05-11 16:24 ` [PATCH v1 1/4] iommu: Move Hyper-V IOMMU driver to its own subdirectory Yu Zhang
` (3 more replies)
0 siblings, 4 replies; 6+ messages in thread
From: Yu Zhang @ 2026-05-11 16:24 UTC (permalink / raw)
To: linux-kernel, linux-hyperv, iommu, linux-pci, linux-arch
Cc: wei.liu, kys, haiyangz, decui, longli, joro, will, robin.murphy,
bhelgaas, kwilczynski, lpieralisi, mani, robh, arnd, jgg,
mhklinux, jacob.pan, tgopinath, easwar.hariharan
This patch series introduces a para-virtualized IOMMU driver for
Linux guests running on Microsoft Hyper-V. The driver enables two
primary use cases:
1) In-kernel DMA protection for devices assigned to the guest.
2) Device assignment to guest user space (e.g., via VFIO).
The driver implements the following core functionality:
* Hypercall-based Enumeration
Unlike traditional ACPI-based discovery (e.g., DMAR/IVRS),
this driver enumerates the Hyper-V IOMMU capabilities directly
via hypercalls. This approach allows the guest to discover
IOMMU presence and features without requiring specific virtual
firmware extensions or modifications.
* Domain Management
The driver manages IOMMU domains through a new set of Hyper-V
hypercall interfaces, handling domain allocation, attachment,
and detachment for endpoint devices.
* Nested Translation Support
This implementation leverages guest-managed stage-1 I/O page
tables nested with host stage-2 translations. It is built
upon the consolidated IOMMU page table framework (IOMMU_PT).
This design eliminates the need for emulating map operations.
Both Intel VT-d and AMD IOMMU platforms are supported.
* IOTLB Invalidation
IOTLB invalidation requests are marshaled and issued to the
hypervisor through the same hypercall mechanism. Both domain-
selective and page-selective flushes are supported.
Implementation Notes:
* Platform Support
The current implementation targets x86 platforms with Intel
VT-d and AMD IOMMU hardware.
* MSI Region Handling
The hardware MSI region is hard-coded to the standard x86
interrupt range (0xfee00000 - 0xfeefffff). Future updates may
allow this configuration to be queried via hypercalls if new
hardware platforms are to be supported.
* Reserved Regions (RMRR)
There is currently no requirement to support assigned devices with
ACPI RMRR limitations. Consequently, this patch series does not
specify or query reserved memory regions.
Testing:
This series has been validated with the following configurations:
- Intel DSA devices assigned to the guest, tested with dmatest.
- NVMe devices assigned to the guest on AMD platforms, tested
with fio.
- dma_map_benchmark for DMA mapping performance evaluation.
Changes since RFC v1 [1]:
- Scoped platform support to x86 only (Intel VT-d and AMD IOMMU);
initialization now uses x86_init.iommu.iommu_init
- Added page-selective IOTLB flush support (new Patch 4)
- Disable device ATS in hv_iommu_release_device()
- Addressed review comments from Michael Kelley:
- Reversed dependency: pvIOMMU exports registration API for
pci-hyperv to call, instead of pci-hyperv exporting
hv_build_logical_dev_id()
- Dropped separate output page allocation patch; hypercall input
and output now share the same per-CPU page
- Cleaned up Kconfig (removed PCI_HYPERV dependency, unnecessary
selects)
- Removed dev_list, per-domain spinlock, and syscore_ops
- Removed forward declarations by reordering functions
- Fixed typos, cleaned up Kconfig selects, improved pr_info
messages, etc.
[1] https://lore.kernel.org/linux-hyperv/20251209051128.76913-1-zhangyu1@linux.microsoft.com/
Easwar Hariharan (1):
iommu: Move Hyper-V IOMMU driver to its own subdirectory
Wei Liu (1):
hyperv: Introduce new hypercall interfaces used by Hyper-V guest IOMMU
Yu Zhang (2):
iommu/hyperv: Add para-virtualized IOMMU support for Hyper-V guest
iommu/hyperv: Add page-selective IOTLB flush support
MAINTAINERS | 2 +-
arch/x86/hyperv/hv_init.c | 4 +
arch/x86/include/asm/mshyperv.h | 4 +
drivers/iommu/Kconfig | 10 +-
drivers/iommu/Makefile | 2 +-
drivers/iommu/hyperv/Kconfig | 27 +
drivers/iommu/hyperv/Makefile | 3 +
drivers/iommu/hyperv/iommu.c | 794 ++++++++++++++++++
drivers/iommu/hyperv/iommu.h | 54 ++
.../irq_remapping.c} | 2 +-
drivers/pci/controller/pci-hyperv.c | 19 +-
include/asm-generic/mshyperv.h | 12 +
include/hyperv/hvgdk_mini.h | 9 +
include/hyperv/hvhdk_mini.h | 141 ++++
14 files changed, 1070 insertions(+), 13 deletions(-)
create mode 100644 drivers/iommu/hyperv/Kconfig
create mode 100644 drivers/iommu/hyperv/Makefile
create mode 100644 drivers/iommu/hyperv/iommu.c
create mode 100644 drivers/iommu/hyperv/iommu.h
rename drivers/iommu/{hyperv-iommu.c => hyperv/irq_remapping.c} (99%)
--
2.52.0
^ permalink raw reply [flat|nested] 6+ messages in thread* [PATCH v1 1/4] iommu: Move Hyper-V IOMMU driver to its own subdirectory 2026-05-11 16:24 [PATCH v1 0/4] Hyper-V: Add para-virtualized IOMMU support for Linux guests Yu Zhang @ 2026-05-11 16:24 ` Yu Zhang 2026-05-11 16:24 ` [PATCH v1 2/4] hyperv: Introduce new hypercall interfaces used by Hyper-V guest IOMMU Yu Zhang ` (2 subsequent siblings) 3 siblings, 0 replies; 6+ messages in thread From: Yu Zhang @ 2026-05-11 16:24 UTC (permalink / raw) To: linux-kernel, linux-hyperv, iommu, linux-pci, linux-arch Cc: wei.liu, kys, haiyangz, decui, longli, joro, will, robin.murphy, bhelgaas, kwilczynski, lpieralisi, mani, robh, arnd, jgg, mhklinux, jacob.pan, tgopinath, easwar.hariharan From: Easwar Hariharan <eahariha@linux.microsoft.com> The Hyper-V IOMMU driver currently only supports IRQ remapping. As it will be adding DMA remapping support, prepare a directory to contain all the different feature files. This is a simple rename commit and has no functional changes. Signed-off-by: Easwar Hariharan <eahariha@linux.microsoft.com> Signed-off-by: Yu Zhang <zhangyu1@linux.microsoft.com> --- MAINTAINERS | 2 +- drivers/iommu/Kconfig | 10 +--------- drivers/iommu/Makefile | 2 +- drivers/iommu/hyperv/Kconfig | 10 ++++++++++ drivers/iommu/hyperv/Makefile | 2 ++ .../iommu/{hyperv-iommu.c => hyperv/irq_remapping.c} | 2 +- 6 files changed, 16 insertions(+), 12 deletions(-) create mode 100644 drivers/iommu/hyperv/Kconfig create mode 100644 drivers/iommu/hyperv/Makefile rename drivers/iommu/{hyperv-iommu.c => hyperv/irq_remapping.c} (99%) diff --git a/MAINTAINERS b/MAINTAINERS index b2040011a386..1519de2a2a09 100644 --- a/MAINTAINERS +++ b/MAINTAINERS @@ -11979,7 +11979,7 @@ F: drivers/clocksource/hyperv_timer.c F: drivers/hid/hid-hyperv.c F: drivers/hv/ F: drivers/input/serio/hyperv-keyboard.c -F: drivers/iommu/hyperv-iommu.c +F: drivers/iommu/hyperv/ F: drivers/net/ethernet/microsoft/ F: drivers/net/hyperv/ F: drivers/pci/controller/pci-hyperv-intf.c diff --git a/drivers/iommu/Kconfig b/drivers/iommu/Kconfig index f86262b11416..0bdf2ac3d782 100644 --- a/drivers/iommu/Kconfig +++ b/drivers/iommu/Kconfig @@ -195,6 +195,7 @@ config MSM_IOMMU source "drivers/iommu/amd/Kconfig" source "drivers/iommu/arm/Kconfig" source "drivers/iommu/intel/Kconfig" +source "drivers/iommu/hyperv/Kconfig" source "drivers/iommu/iommufd/Kconfig" source "drivers/iommu/riscv/Kconfig" @@ -351,15 +352,6 @@ config MTK_IOMMU_V1 if unsure, say N here. -config HYPERV_IOMMU - bool "Hyper-V IRQ Handling" - depends on HYPERV && X86 - select IOMMU_API - default HYPERV - help - Stub IOMMU driver to handle IRQs to support Hyper-V Linux - guest and root partitions. - config VIRTIO_IOMMU tristate "Virtio IOMMU driver" depends on VIRTIO diff --git a/drivers/iommu/Makefile b/drivers/iommu/Makefile index 0275821f4ef9..32f3ca758556 100644 --- a/drivers/iommu/Makefile +++ b/drivers/iommu/Makefile @@ -4,6 +4,7 @@ obj-$(CONFIG_AMD_IOMMU) += amd/ obj-$(CONFIG_INTEL_IOMMU) += intel/ obj-$(CONFIG_RISCV_IOMMU) += riscv/ obj-$(CONFIG_GENERIC_PT) += generic_pt/fmt/ +obj-$(CONFIG_HYPERV_IOMMU) += hyperv/ obj-$(CONFIG_IOMMU_API) += iommu.o obj-$(CONFIG_IOMMU_SUPPORT) += iommu-pages.o obj-$(CONFIG_IOMMU_API) += iommu-traces.o @@ -30,7 +31,6 @@ obj-$(CONFIG_TEGRA_IOMMU_SMMU) += tegra-smmu.o obj-$(CONFIG_EXYNOS_IOMMU) += exynos-iommu.o obj-$(CONFIG_FSL_PAMU) += fsl_pamu.o fsl_pamu_domain.o obj-$(CONFIG_S390_IOMMU) += s390-iommu.o -obj-$(CONFIG_HYPERV_IOMMU) += hyperv-iommu.o obj-$(CONFIG_VIRTIO_IOMMU) += virtio-iommu.o obj-$(CONFIG_IOMMU_SVA) += iommu-sva.o obj-$(CONFIG_IOMMU_IOPF) += io-pgfault.o diff --git a/drivers/iommu/hyperv/Kconfig b/drivers/iommu/hyperv/Kconfig new file mode 100644 index 000000000000..30f40d867036 --- /dev/null +++ b/drivers/iommu/hyperv/Kconfig @@ -0,0 +1,10 @@ +# SPDX-License-Identifier: GPL-2.0-only +# HyperV paravirtualized IOMMU support +config HYPERV_IOMMU + bool "Hyper-V IRQ Handling" + depends on HYPERV && X86 + select IOMMU_API + default HYPERV + help + Stub IOMMU driver to handle IRQs to support Hyper-V Linux + guest and root partitions. diff --git a/drivers/iommu/hyperv/Makefile b/drivers/iommu/hyperv/Makefile new file mode 100644 index 000000000000..9f557bad94ff --- /dev/null +++ b/drivers/iommu/hyperv/Makefile @@ -0,0 +1,2 @@ +# SPDX-License-Identifier: GPL-2.0 +obj-$(CONFIG_HYPERV_IOMMU) += irq_remapping.o diff --git a/drivers/iommu/hyperv-iommu.c b/drivers/iommu/hyperv/irq_remapping.c similarity index 99% rename from drivers/iommu/hyperv-iommu.c rename to drivers/iommu/hyperv/irq_remapping.c index 479103261ae6..62a94a8c9e95 100644 --- a/drivers/iommu/hyperv-iommu.c +++ b/drivers/iommu/hyperv/irq_remapping.c @@ -22,7 +22,7 @@ #include <asm/hypervisor.h> #include <asm/mshyperv.h> -#include "irq_remapping.h" +#include "../irq_remapping.h" #ifdef CONFIG_IRQ_REMAP -- 2.52.0 ^ permalink raw reply related [flat|nested] 6+ messages in thread
* [PATCH v1 2/4] hyperv: Introduce new hypercall interfaces used by Hyper-V guest IOMMU 2026-05-11 16:24 [PATCH v1 0/4] Hyper-V: Add para-virtualized IOMMU support for Linux guests Yu Zhang 2026-05-11 16:24 ` [PATCH v1 1/4] iommu: Move Hyper-V IOMMU driver to its own subdirectory Yu Zhang @ 2026-05-11 16:24 ` Yu Zhang 2026-05-11 16:24 ` [PATCH v1 3/4] iommu/hyperv: Add para-virtualized IOMMU support for Hyper-V guest Yu Zhang 2026-05-11 16:24 ` [PATCH v1 4/4] iommu/hyperv: Add page-selective IOTLB flush support Yu Zhang 3 siblings, 0 replies; 6+ messages in thread From: Yu Zhang @ 2026-05-11 16:24 UTC (permalink / raw) To: linux-kernel, linux-hyperv, iommu, linux-pci, linux-arch Cc: wei.liu, kys, haiyangz, decui, longli, joro, will, robin.murphy, bhelgaas, kwilczynski, lpieralisi, mani, robh, arnd, jgg, mhklinux, jacob.pan, tgopinath, easwar.hariharan 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). Signed-off-by: Wei Liu <wei.liu@kernel.org> 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 | 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) + + 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) + 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 ^ permalink raw reply related [flat|nested] 6+ messages in thread
* [PATCH v1 3/4] iommu/hyperv: Add para-virtualized IOMMU support for Hyper-V guest 2026-05-11 16:24 [PATCH v1 0/4] Hyper-V: Add para-virtualized IOMMU support for Linux guests Yu Zhang 2026-05-11 16:24 ` [PATCH v1 1/4] iommu: Move Hyper-V IOMMU driver to its own subdirectory Yu Zhang 2026-05-11 16:24 ` [PATCH v1 2/4] hyperv: Introduce new hypercall interfaces used by Hyper-V guest IOMMU Yu Zhang @ 2026-05-11 16:24 ` Yu Zhang 2026-05-13 18:39 ` Jacob Pan 2026-05-11 16:24 ` [PATCH v1 4/4] iommu/hyperv: Add page-selective IOTLB flush support Yu Zhang 3 siblings, 1 reply; 6+ messages in thread From: Yu Zhang @ 2026-05-11 16:24 UTC (permalink / raw) To: linux-kernel, linux-hyperv, iommu, linux-pci, linux-arch Cc: wei.liu, kys, haiyangz, decui, longli, joro, will, robin.murphy, bhelgaas, kwilczynski, lpieralisi, mani, robh, arnd, jgg, mhklinux, jacob.pan, tgopinath, easwar.hariharan Add a para-virtualized IOMMU driver for Linux guests running on Hyper-V. This driver implements stage-1 IO translation within the guest OS. It integrates with the Linux IOMMU core, utilizing Hyper-V hypercalls for: - Capability discovery - Domain allocation, configuration, and deallocation - Device attachment and detachment - IOTLB invalidation The driver constructs x86-compatible stage-1 IO page tables in the guest memory using consolidated IO page table helpers. This allows the guest to manage stage-1 translations independently of vendor- specific drivers (like Intel VT-d or AMD IOMMU). Hyper-V consumes this stage-1 IO page table when a device domain is created and configured, and nests it with the host's stage-2 IO page tables, therefore eliminating the VM exits for guest IOMMU mapping operations. For unmapping operations, VM exits to perform the IOTLB flush are still unavoidable. Hyper-V identifies each PCI pass-thru device by a logical device ID in its hypercall interface. The vPCI driver (pci-hyperv) registers the per-bus portion of this ID with the pvIOMMU driver during bus probe. The pvIOMMU driver stores this mapping and combines it with the function number of the endpoint PCI device to form the complete ID for hypercalls. Co-developed-by: Wei Liu <wei.liu@kernel.org> Signed-off-by: Wei Liu <wei.liu@kernel.org> Co-developed-by: Easwar Hariharan <easwar.hariharan@linux.microsoft.com> Signed-off-by: Easwar Hariharan <easwar.hariharan@linux.microsoft.com> Signed-off-by: Yu Zhang <zhangyu1@linux.microsoft.com> --- arch/x86/hyperv/hv_init.c | 4 + arch/x86/include/asm/mshyperv.h | 4 + drivers/iommu/hyperv/Kconfig | 17 + drivers/iommu/hyperv/Makefile | 1 + drivers/iommu/hyperv/iommu.c | 705 ++++++++++++++++++++++++++++ drivers/iommu/hyperv/iommu.h | 54 +++ drivers/pci/controller/pci-hyperv.c | 19 +- include/asm-generic/mshyperv.h | 12 + 8 files changed, 815 insertions(+), 1 deletion(-) create mode 100644 drivers/iommu/hyperv/iommu.c create mode 100644 drivers/iommu/hyperv/iommu.h diff --git a/arch/x86/hyperv/hv_init.c b/arch/x86/hyperv/hv_init.c index 323adc93f2dc..2c8ff8e06249 100644 --- a/arch/x86/hyperv/hv_init.c +++ b/arch/x86/hyperv/hv_init.c @@ -578,6 +578,10 @@ void __init hyperv_init(void) old_setup_percpu_clockev = x86_init.timers.setup_percpu_clockev; x86_init.timers.setup_percpu_clockev = hv_stimer_setup_percpu_clockev; +#ifdef CONFIG_HYPERV_PVIOMMU + x86_init.iommu.iommu_init = hv_iommu_init; +#endif + hv_apic_init(); x86_init.pci.arch_init = hv_pci_init; diff --git a/arch/x86/include/asm/mshyperv.h b/arch/x86/include/asm/mshyperv.h index f64393e853ee..20d947c2c758 100644 --- a/arch/x86/include/asm/mshyperv.h +++ b/arch/x86/include/asm/mshyperv.h @@ -313,6 +313,10 @@ static inline void mshv_vtl_return_hypercall(void) {} static inline void __mshv_vtl_return_call(struct mshv_vtl_cpu_context *vtl0) {} #endif +#ifdef CONFIG_HYPERV_PVIOMMU +int __init hv_iommu_init(void); +#endif + #include <asm-generic/mshyperv.h> #endif diff --git a/drivers/iommu/hyperv/Kconfig b/drivers/iommu/hyperv/Kconfig index 30f40d867036..9e658d5c9a77 100644 --- a/drivers/iommu/hyperv/Kconfig +++ b/drivers/iommu/hyperv/Kconfig @@ -8,3 +8,20 @@ config HYPERV_IOMMU help Stub IOMMU driver to handle IRQs to support Hyper-V Linux guest and root partitions. + +if HYPERV_IOMMU +config HYPERV_PVIOMMU + bool "Microsoft Hypervisor para-virtualized IOMMU support" + depends on X86 && HYPERV + select IOMMU_API + select GENERIC_PT + select IOMMU_PT + select IOMMU_PT_X86_64 + select IOMMU_IOVA + default HYPERV + help + Para-virtualized IOMMU driver for Linux guests running on + Microsoft Hyper-V. Provides DMA remapping and IOTLB + flush support to enable DMA isolation for devices + assigned to the guest. +endif diff --git a/drivers/iommu/hyperv/Makefile b/drivers/iommu/hyperv/Makefile index 9f557bad94ff..8669741c0a51 100644 --- a/drivers/iommu/hyperv/Makefile +++ b/drivers/iommu/hyperv/Makefile @@ -1,2 +1,3 @@ # SPDX-License-Identifier: GPL-2.0 obj-$(CONFIG_HYPERV_IOMMU) += irq_remapping.o +obj-$(CONFIG_HYPERV_PVIOMMU) += iommu.o diff --git a/drivers/iommu/hyperv/iommu.c b/drivers/iommu/hyperv/iommu.c new file mode 100644 index 000000000000..e5fc625314b5 --- /dev/null +++ b/drivers/iommu/hyperv/iommu.c @@ -0,0 +1,705 @@ +// SPDX-License-Identifier: GPL-2.0 + +/* + * Hyper-V IOMMU driver. + * + * Copyright (C) 2019, 2024-2026 Microsoft, Inc. + */ + +#define pr_fmt(fmt) "Hyper-V pvIOMMU: " fmt +#define dev_fmt(fmt) pr_fmt(fmt) + +#include <linux/iommu.h> +#include <linux/pci.h> +#include <linux/dma-map-ops.h> +#include <linux/generic_pt/iommu.h> +#include <linux/pci-ats.h> + +#include <asm/iommu.h> +#include <asm/hypervisor.h> +#include <asm/mshyperv.h> + +#include "iommu.h" +#include "../iommu-pages.h" + +struct hv_iommu_dev *hv_iommu_device; + +/* + * Identity and blocking domains are static singletons: identity is a 1:1 + * passthrough with no page table, blocking rejects all DMA. Neither holds + * per-IOMMU state, so one instance suffices even with multiple vIOMMUs. + */ +static struct hv_iommu_domain hv_identity_domain; +static struct hv_iommu_domain hv_blocking_domain; +static const struct iommu_domain_ops hv_iommu_identity_domain_ops; +static const struct iommu_domain_ops hv_iommu_blocking_domain_ops; +static struct iommu_ops hv_iommu_ops; +static LIST_HEAD(hv_iommu_pci_bus_list); +static DEFINE_SPINLOCK(hv_iommu_pci_bus_lock); + +#define hv_iommu_present(iommu_cap) (iommu_cap & HV_IOMMU_CAP_PRESENT) +#define hv_iommu_s1_domain_supported(iommu_cap) (iommu_cap & HV_IOMMU_CAP_S1) +#define hv_iommu_5lvl_supported(iommu_cap) (iommu_cap & HV_IOMMU_CAP_S1_5LVL) +#define hv_iommu_ats_supported(iommu_cap) (iommu_cap & HV_IOMMU_CAP_ATS) + +int hv_iommu_register_pci_bus(int pci_domain_nr, u32 logical_dev_id_prefix) +{ + struct hv_pci_busdata *bus, *new; + int ret = 0; + + if (no_iommu || !iommu_detected) + return 0; + + new = kzalloc_obj(*new, GFP_KERNEL); + if (!new) + return -ENOMEM; + + spin_lock(&hv_iommu_pci_bus_lock); + list_for_each_entry(bus, &hv_iommu_pci_bus_list, list) { + if (bus->pci_domain_nr != pci_domain_nr) + continue; + + if (bus->logical_dev_id_prefix != logical_dev_id_prefix) { + pr_err("stale registration for PCI domain %d (old prefix 0x%08x, new 0x%08x)\n", + pci_domain_nr, bus->logical_dev_id_prefix, + logical_dev_id_prefix); + ret = -EEXIST; + } + + goto out_free; + } + + new->pci_domain_nr = pci_domain_nr; + new->logical_dev_id_prefix = logical_dev_id_prefix; + list_add(&new->list, &hv_iommu_pci_bus_list); + spin_unlock(&hv_iommu_pci_bus_lock); + return 0; + +out_free: + spin_unlock(&hv_iommu_pci_bus_lock); + kfree(new); + return ret; +} +EXPORT_SYMBOL_FOR_MODULES(hv_iommu_register_pci_bus, "pci-hyperv"); + +void hv_iommu_unregister_pci_bus(int pci_domain_nr) +{ + struct hv_pci_busdata *bus, *tmp; + + spin_lock(&hv_iommu_pci_bus_lock); + list_for_each_entry_safe(bus, tmp, &hv_iommu_pci_bus_list, list) { + if (bus->pci_domain_nr == pci_domain_nr) { + list_del(&bus->list); + kfree(bus); + break; + } + } + spin_unlock(&hv_iommu_pci_bus_lock); +} +EXPORT_SYMBOL_FOR_MODULES(hv_iommu_unregister_pci_bus, "pci-hyperv"); + +/* + * Look up the logical device ID for a vPCI device. Returns 0 on success + * with *logical_id filled in; -ENODEV if no entry registered for this + * device's vPCI bus. + */ +static int hv_iommu_lookup_logical_dev_id(struct pci_dev *pdev, u64 *logical_id) +{ + struct hv_pci_busdata *bus; + int domain = pci_domain_nr(pdev->bus); + int ret = -ENODEV; + + spin_lock(&hv_iommu_pci_bus_lock); + list_for_each_entry(bus, &hv_iommu_pci_bus_list, list) { + if (bus->pci_domain_nr == domain) { + *logical_id = (u64)bus->logical_dev_id_prefix | + PCI_FUNC(pdev->devfn); + ret = 0; + break; + } + } + spin_unlock(&hv_iommu_pci_bus_lock); + return ret; +} + +static int hv_create_device_domain(struct hv_iommu_domain *hv_domain, u32 domain_stage) +{ + int ret; + u64 status; + unsigned long flags; + struct hv_input_create_device_domain *input; + + ret = ida_alloc_range(&hv_iommu_device->domain_ids, + hv_iommu_device->first_domain, hv_iommu_device->last_domain, + GFP_KERNEL); + if (ret < 0) + return ret; + + hv_domain->device_domain.partition_id = HV_PARTITION_ID_SELF; + hv_domain->device_domain.domain_id.type = domain_stage; + hv_domain->device_domain.domain_id.id = ret; + hv_domain->hv_iommu = hv_iommu_device; + + local_irq_save(flags); + + input = *this_cpu_ptr(hyperv_pcpu_input_arg); + memset(input, 0, sizeof(*input)); + input->device_domain = hv_domain->device_domain; + input->create_device_domain_flags.forward_progress_required = 1; + input->create_device_domain_flags.inherit_owning_vtl = 0; + status = hv_do_hypercall(HVCALL_CREATE_DEVICE_DOMAIN, input, NULL); + + local_irq_restore(flags); + + if (!hv_result_success(status)) { + pr_err("HVCALL_CREATE_DEVICE_DOMAIN failed, status %lld\n", status); + ida_free(&hv_iommu_device->domain_ids, hv_domain->device_domain.domain_id.id); + } + + return hv_result_to_errno(status); +} + +static void hv_delete_device_domain(struct hv_iommu_domain *hv_domain) +{ + u64 status; + unsigned long flags; + struct hv_input_delete_device_domain *input; + + local_irq_save(flags); + + input = *this_cpu_ptr(hyperv_pcpu_input_arg); + memset(input, 0, sizeof(*input)); + input->device_domain = hv_domain->device_domain; + status = hv_do_hypercall(HVCALL_DELETE_DEVICE_DOMAIN, input, NULL); + + local_irq_restore(flags); + + if (!hv_result_success(status)) + pr_err("HVCALL_DELETE_DEVICE_DOMAIN failed, status %lld\n", status); + + ida_free(&hv_domain->hv_iommu->domain_ids, hv_domain->device_domain.domain_id.id); +} + +static bool hv_iommu_capable(struct device *dev, enum iommu_cap cap) +{ + switch (cap) { + case IOMMU_CAP_CACHE_COHERENCY: + return true; + case IOMMU_CAP_DEFERRED_FLUSH: + return true; + default: + return false; + } +} + +static void hv_flush_device_domain(struct hv_iommu_domain *hv_domain) +{ + u64 status; + unsigned long flags; + struct hv_input_flush_device_domain *input; + + local_irq_save(flags); + + input = *this_cpu_ptr(hyperv_pcpu_input_arg); + memset(input, 0, sizeof(*input)); + input->device_domain = hv_domain->device_domain; + status = hv_do_hypercall(HVCALL_FLUSH_DEVICE_DOMAIN, input, NULL); + + local_irq_restore(flags); + + if (!hv_result_success(status)) + pr_err("HVCALL_FLUSH_DEVICE_DOMAIN failed, status %lld\n", status); +} + +static void hv_iommu_detach_dev(struct iommu_domain *domain, struct device *dev) +{ + u64 status; + unsigned long flags; + struct hv_input_detach_device_domain *input; + struct pci_dev *pdev; + struct hv_iommu_domain *hv_domain = to_hv_iommu_domain(domain); + struct hv_iommu_endpoint *vdev = dev_iommu_priv_get(dev); + + /* See the attach function, only PCI devices for now */ + if (!dev_is_pci(dev) || vdev->hv_domain != hv_domain) + return; + + pdev = to_pci_dev(dev); + + dev_dbg(dev, "detaching from domain %d\n", hv_domain->device_domain.domain_id.id); + + local_irq_save(flags); + + input = *this_cpu_ptr(hyperv_pcpu_input_arg); + memset(input, 0, sizeof(*input)); + input->partition_id = HV_PARTITION_ID_SELF; + if (hv_iommu_lookup_logical_dev_id(pdev, &input->device_id.as_uint64)) { + local_irq_restore(flags); + dev_warn(&pdev->dev, "no IOMMU registration for vPCI bus on detach\n"); + return; + } + status = hv_do_hypercall(HVCALL_DETACH_DEVICE_DOMAIN, input, NULL); + + local_irq_restore(flags); + + if (!hv_result_success(status)) + pr_err("HVCALL_DETACH_DEVICE_DOMAIN failed, status %lld\n", status); + + hv_flush_device_domain(hv_domain); + + vdev->hv_domain = NULL; +} + +static int hv_iommu_attach_dev(struct iommu_domain *domain, struct device *dev, + struct iommu_domain *old) +{ + u64 status; + unsigned long flags; + struct pci_dev *pdev; + struct hv_input_attach_device_domain *input; + struct hv_iommu_endpoint *vdev = dev_iommu_priv_get(dev); + struct hv_iommu_domain *hv_domain = to_hv_iommu_domain(domain); + int ret; + + /* Only allow PCI devices for now */ + if (!dev_is_pci(dev)) + return -EINVAL; + + if (vdev->hv_domain == hv_domain) + return 0; + + if (vdev->hv_domain) + hv_iommu_detach_dev(&vdev->hv_domain->domain, dev); + + pdev = to_pci_dev(dev); + dev_dbg(dev, "attaching to domain %d\n", + hv_domain->device_domain.domain_id.id); + + local_irq_save(flags); + + input = *this_cpu_ptr(hyperv_pcpu_input_arg); + memset(input, 0, sizeof(*input)); + input->device_domain = hv_domain->device_domain; + ret = hv_iommu_lookup_logical_dev_id(pdev, &input->device_id.as_uint64); + if (ret) { + local_irq_restore(flags); + dev_err(&pdev->dev, "no IOMMU registration for vPCI bus\n"); + return ret; + } + status = hv_do_hypercall(HVCALL_ATTACH_DEVICE_DOMAIN, input, NULL); + + local_irq_restore(flags); + + if (!hv_result_success(status)) + pr_err("HVCALL_ATTACH_DEVICE_DOMAIN failed, status %lld\n", status); + else + vdev->hv_domain = hv_domain; + + return hv_result_to_errno(status); +} + +static int hv_iommu_get_logical_device_property(struct device *dev, + u32 code, + struct hv_output_get_logical_device_property *property) +{ + u64 status, lid; + unsigned long flags; + int ret; + struct hv_input_get_logical_device_property *input; + struct hv_output_get_logical_device_property *output; + + local_irq_save(flags); + + input = *this_cpu_ptr(hyperv_pcpu_input_arg); + output = *this_cpu_ptr(hyperv_pcpu_input_arg) + sizeof(*input); + memset(input, 0, sizeof(*input)); + input->partition_id = HV_PARTITION_ID_SELF; + ret = hv_iommu_lookup_logical_dev_id(to_pci_dev(dev), &lid); + if (ret) { + local_irq_restore(flags); + return ret; + } + input->logical_device_id = lid; + input->code = code; + status = hv_do_hypercall(HVCALL_GET_LOGICAL_DEVICE_PROPERTY, input, output); + *property = *output; + + local_irq_restore(flags); + + if (!hv_result_success(status)) + pr_err("HVCALL_GET_LOGICAL_DEVICE_PROPERTY failed, status %lld\n", status); + + return hv_result_to_errno(status); +} + +static struct iommu_device *hv_iommu_probe_device(struct device *dev) +{ + struct pci_dev *pdev; + struct hv_iommu_endpoint *vdev; + struct hv_output_get_logical_device_property device_iommu_property = {0}; + + if (!dev_is_pci(dev)) + return ERR_PTR(-ENODEV); + + pdev = to_pci_dev(dev); + + if (hv_iommu_get_logical_device_property(dev, + HV_LOGICAL_DEVICE_PROPERTY_PVIOMMU, + &device_iommu_property) || + !(device_iommu_property.device_iommu & HV_DEVICE_IOMMU_ENABLED)) + return ERR_PTR(-ENODEV); + + vdev = kzalloc_obj(*vdev, GFP_KERNEL); + if (!vdev) + return ERR_PTR(-ENOMEM); + + vdev->dev = dev; + vdev->hv_iommu = hv_iommu_device; + dev_iommu_priv_set(dev, vdev); + + if (hv_iommu_ats_supported(hv_iommu_device->cap) && + pci_ats_supported(pdev)) + pci_enable_ats(pdev, __ffs(hv_iommu_device->pgsize_bitmap)); + + return &vdev->hv_iommu->iommu; +} + +static void hv_iommu_release_device(struct device *dev) +{ + struct hv_iommu_endpoint *vdev = dev_iommu_priv_get(dev); + struct pci_dev *pdev = to_pci_dev(dev); + + if (pdev->ats_enabled) + pci_disable_ats(pdev); + + dev_iommu_priv_set(dev, NULL); + set_dma_ops(dev, NULL); + + kfree(vdev); +} + +static struct iommu_group *hv_iommu_device_group(struct device *dev) +{ + if (dev_is_pci(dev)) + return pci_device_group(dev); + else + return generic_device_group(dev); +} + +static int hv_configure_device_domain(struct hv_iommu_domain *hv_domain, u32 domain_type) +{ + u64 status; + unsigned long flags; + struct pt_iommu_x86_64_hw_info pt_info; + struct hv_input_configure_device_domain *input; + + local_irq_save(flags); + + input = *this_cpu_ptr(hyperv_pcpu_input_arg); + memset(input, 0, sizeof(*input)); + input->device_domain = hv_domain->device_domain; + input->settings.flags.blocked = (domain_type == IOMMU_DOMAIN_BLOCKED); + input->settings.flags.translation_enabled = (domain_type != IOMMU_DOMAIN_IDENTITY); + + if (domain_type & __IOMMU_DOMAIN_PAGING) { + pt_iommu_x86_64_hw_info(&hv_domain->pt_iommu_x86_64, &pt_info); + input->settings.page_table_root = pt_info.gcr3_pt; + input->settings.flags.first_stage_paging_mode = + pt_info.levels == 5; + } + status = hv_do_hypercall(HVCALL_CONFIGURE_DEVICE_DOMAIN, input, NULL); + + local_irq_restore(flags); + + if (!hv_result_success(status)) + pr_err("HVCALL_CONFIGURE_DEVICE_DOMAIN failed, status %lld\n", status); + + return hv_result_to_errno(status); +} + +static int __init hv_initialize_static_domains(void) +{ + int ret; + struct hv_iommu_domain *hv_domain; + + /* Default stage-1 identity domain */ + hv_domain = &hv_identity_domain; + + ret = hv_create_device_domain(hv_domain, HV_DEVICE_DOMAIN_TYPE_S1); + if (ret) + return ret; + + ret = hv_configure_device_domain(hv_domain, IOMMU_DOMAIN_IDENTITY); + if (ret) + goto delete_identity_domain; + + hv_domain->domain.type = IOMMU_DOMAIN_IDENTITY; + hv_domain->domain.ops = &hv_iommu_identity_domain_ops; + hv_domain->domain.owner = &hv_iommu_ops; + hv_domain->domain.geometry = hv_iommu_device->geometry; + hv_domain->domain.pgsize_bitmap = hv_iommu_device->pgsize_bitmap; + + /* Default stage-1 blocked domain */ + hv_domain = &hv_blocking_domain; + + ret = hv_create_device_domain(hv_domain, HV_DEVICE_DOMAIN_TYPE_S1); + if (ret) + goto delete_identity_domain; + + ret = hv_configure_device_domain(hv_domain, IOMMU_DOMAIN_BLOCKED); + if (ret) + goto delete_blocked_domain; + + hv_domain->domain.type = IOMMU_DOMAIN_BLOCKED; + hv_domain->domain.ops = &hv_iommu_blocking_domain_ops; + hv_domain->domain.owner = &hv_iommu_ops; + hv_domain->domain.geometry = hv_iommu_device->geometry; + hv_domain->domain.pgsize_bitmap = hv_iommu_device->pgsize_bitmap; + + return 0; + +delete_blocked_domain: + hv_delete_device_domain(&hv_blocking_domain); +delete_identity_domain: + hv_delete_device_domain(&hv_identity_domain); + return ret; +} + +#define INTERRUPT_RANGE_START (0xfee00000) +#define INTERRUPT_RANGE_END (0xfeefffff) +static void hv_iommu_get_resv_regions(struct device *dev, + struct list_head *head) +{ + struct iommu_resv_region *region; + + region = iommu_alloc_resv_region(INTERRUPT_RANGE_START, + INTERRUPT_RANGE_END - INTERRUPT_RANGE_START + 1, + 0, IOMMU_RESV_MSI, GFP_KERNEL); + if (!region) + return; + + list_add_tail(®ion->list, head); +} + +static void hv_iommu_flush_iotlb_all(struct iommu_domain *domain) +{ + hv_flush_device_domain(to_hv_iommu_domain(domain)); +} + +static void hv_iommu_iotlb_sync(struct iommu_domain *domain, + struct iommu_iotlb_gather *iotlb_gather) +{ + hv_flush_device_domain(to_hv_iommu_domain(domain)); + + iommu_put_pages_list(&iotlb_gather->freelist); +} + +static void hv_iommu_paging_domain_free(struct iommu_domain *domain) +{ + struct hv_iommu_domain *hv_domain = to_hv_iommu_domain(domain); + + /* Free all remaining mappings */ + pt_iommu_deinit(&hv_domain->pt_iommu); + + hv_delete_device_domain(hv_domain); + + kfree(hv_domain); +} + +static const struct iommu_domain_ops hv_iommu_identity_domain_ops = { + .attach_dev = hv_iommu_attach_dev, +}; + +static const struct iommu_domain_ops hv_iommu_blocking_domain_ops = { + .attach_dev = hv_iommu_attach_dev, +}; + +static const struct iommu_domain_ops hv_iommu_paging_domain_ops = { + .attach_dev = hv_iommu_attach_dev, + IOMMU_PT_DOMAIN_OPS(x86_64), + .flush_iotlb_all = hv_iommu_flush_iotlb_all, + .iotlb_sync = hv_iommu_iotlb_sync, + .free = hv_iommu_paging_domain_free, +}; + +static struct iommu_domain *hv_iommu_domain_alloc_paging(struct device *dev) +{ + int ret; + struct hv_iommu_domain *hv_domain; + struct pt_iommu_x86_64_cfg cfg = {}; + + hv_domain = kzalloc_obj(*hv_domain, GFP_KERNEL); + if (!hv_domain) + return ERR_PTR(-ENOMEM); + + ret = hv_create_device_domain(hv_domain, HV_DEVICE_DOMAIN_TYPE_S1); + if (ret) { + kfree(hv_domain); + return ERR_PTR(ret); + } + + hv_domain->domain.geometry = hv_iommu_device->geometry; + hv_domain->pt_iommu.nid = dev_to_node(dev); + + cfg.common.hw_max_vasz_lg2 = hv_iommu_device->max_iova_width; + cfg.common.hw_max_oasz_lg2 = 52; + cfg.top_level = (hv_iommu_device->max_iova_width > 48) ? 4 : 3; + + ret = pt_iommu_x86_64_init(&hv_domain->pt_iommu_x86_64, &cfg, GFP_KERNEL); + if (ret) { + hv_delete_device_domain(hv_domain); + kfree(hv_domain); + return ERR_PTR(ret); + } + + /* Constrain to page sizes the hypervisor supports */ + hv_domain->domain.pgsize_bitmap &= hv_iommu_device->pgsize_bitmap; + + hv_domain->domain.ops = &hv_iommu_paging_domain_ops; + + ret = hv_configure_device_domain(hv_domain, __IOMMU_DOMAIN_PAGING); + if (ret) { + pt_iommu_deinit(&hv_domain->pt_iommu); + hv_delete_device_domain(hv_domain); + kfree(hv_domain); + return ERR_PTR(ret); + } + + return &hv_domain->domain; +} + +static struct iommu_ops hv_iommu_ops = { + .capable = hv_iommu_capable, + .domain_alloc_paging = hv_iommu_domain_alloc_paging, + .probe_device = hv_iommu_probe_device, + .release_device = hv_iommu_release_device, + .device_group = hv_iommu_device_group, + .get_resv_regions = hv_iommu_get_resv_regions, + .owner = THIS_MODULE, + .identity_domain = &hv_identity_domain.domain, + .blocked_domain = &hv_blocking_domain.domain, + .release_domain = &hv_blocking_domain.domain, +}; + +static int hv_iommu_detect(struct hv_output_get_iommu_capabilities *hv_iommu_cap) +{ + u64 status; + unsigned long flags; + struct hv_input_get_iommu_capabilities *input; + struct hv_output_get_iommu_capabilities *output; + + local_irq_save(flags); + + input = *this_cpu_ptr(hyperv_pcpu_input_arg); + output = *this_cpu_ptr(hyperv_pcpu_input_arg) + sizeof(*input); + memset(input, 0, sizeof(*input)); + input->partition_id = HV_PARTITION_ID_SELF; + status = hv_do_hypercall(HVCALL_GET_IOMMU_CAPABILITIES, input, output); + *hv_iommu_cap = *output; + + local_irq_restore(flags); + + if (!hv_result_success(status)) + pr_err("HVCALL_GET_IOMMU_CAPABILITIES failed, status %lld\n", status); + + return hv_result_to_errno(status); +} + +static void __init hv_init_iommu_device(struct hv_iommu_dev *hv_iommu, + struct hv_output_get_iommu_capabilities *hv_iommu_cap) +{ + ida_init(&hv_iommu->domain_ids); + + hv_iommu->cap = hv_iommu_cap->iommu_cap; + hv_iommu->max_iova_width = hv_iommu_cap->max_iova_width; + if (!hv_iommu_5lvl_supported(hv_iommu->cap) && + hv_iommu->max_iova_width > 48) { + pr_info("5-level paging not supported, limiting iova width to 48.\n"); + hv_iommu->max_iova_width = 48; + } + + hv_iommu->geometry = (struct iommu_domain_geometry) { + .aperture_start = 0, + .aperture_end = (((u64)1) << hv_iommu->max_iova_width) - 1, + .force_aperture = true, + }; + + hv_iommu->first_domain = HV_DEVICE_DOMAIN_ID_DEFAULT + 1; + hv_iommu->last_domain = HV_DEVICE_DOMAIN_ID_NULL - 1; + /* Only x86 page sizes (4K/2M/1G) are supported */ + hv_iommu->pgsize_bitmap = hv_iommu_cap->pgsize_bitmap & + (SZ_4K | SZ_2M | SZ_1G); + if (hv_iommu->pgsize_bitmap != hv_iommu_cap->pgsize_bitmap) + pr_warn("unsupported page sizes masked: 0x%llx -> 0x%llx\n", + hv_iommu_cap->pgsize_bitmap, hv_iommu->pgsize_bitmap); + if (!hv_iommu->pgsize_bitmap) { + pr_warn("no supported page sizes, defaulting to 4K\n"); + hv_iommu->pgsize_bitmap = SZ_4K; + } + hv_iommu_device = hv_iommu; +} + +int __init hv_iommu_init(void) +{ + int ret = 0; + struct hv_iommu_dev *hv_iommu = NULL; + struct hv_output_get_iommu_capabilities hv_iommu_cap = {0}; + + if (no_iommu || iommu_detected) + return -ENODEV; + + if (!hv_is_hyperv_initialized()) + return -ENODEV; + + ret = hv_iommu_detect(&hv_iommu_cap); + if (ret) { + pr_err("HVCALL_GET_IOMMU_CAPABILITIES failed: %d\n", ret); + return -ENODEV; + } + + if (!hv_iommu_present(hv_iommu_cap.iommu_cap) || + !hv_iommu_s1_domain_supported(hv_iommu_cap.iommu_cap)) { + pr_err("IOMMU capabilities not sufficient: cap=0x%llx\n", + hv_iommu_cap.iommu_cap); + return -ENODEV; + } + + iommu_detected = 1; + pci_request_acs(); + + hv_iommu = kzalloc_obj(*hv_iommu, GFP_KERNEL); + if (!hv_iommu) + return -ENOMEM; + + hv_init_iommu_device(hv_iommu, &hv_iommu_cap); + + ret = hv_initialize_static_domains(); + if (ret) { + pr_err("static domains init failed: %d\n", ret); + goto err_free; + } + + ret = iommu_device_sysfs_add(&hv_iommu->iommu, NULL, NULL, "%s", "hv-iommu"); + if (ret) { + pr_err("iommu_device_sysfs_add failed: %d\n", ret); + goto err_delete_static_domains; + } + + ret = iommu_device_register(&hv_iommu->iommu, &hv_iommu_ops, NULL); + if (ret) { + pr_err("iommu_device_register failed: %d\n", ret); + goto err_sysfs_remove; + } + + pr_info("successfully initialized\n"); + return 0; + +err_sysfs_remove: + iommu_device_sysfs_remove(&hv_iommu->iommu); +err_delete_static_domains: + hv_delete_device_domain(&hv_blocking_domain); + hv_delete_device_domain(&hv_identity_domain); +err_free: + kfree(hv_iommu); + return ret; +} diff --git a/drivers/iommu/hyperv/iommu.h b/drivers/iommu/hyperv/iommu.h new file mode 100644 index 000000000000..43f20d371245 --- /dev/null +++ b/drivers/iommu/hyperv/iommu.h @@ -0,0 +1,54 @@ +/* SPDX-License-Identifier: GPL-2.0 */ + +/* + * Hyper-V IOMMU driver. + * + * Copyright (C) 2024-2025, Microsoft, Inc. + * + */ + +#ifndef _HYPERV_IOMMU_H +#define _HYPERV_IOMMU_H + +struct hv_iommu_dev { + struct iommu_device iommu; + struct ida domain_ids; + + /* Device configuration */ + u8 max_iova_width; + u8 max_pasid_width; + u64 cap; + u64 pgsize_bitmap; + + struct iommu_domain_geometry geometry; + u64 first_domain; + u64 last_domain; +}; + +struct hv_iommu_domain { + union { + struct iommu_domain domain; + struct pt_iommu pt_iommu; + struct pt_iommu_x86_64 pt_iommu_x86_64; + }; + struct hv_iommu_dev *hv_iommu; + struct hv_input_device_domain device_domain; + u64 pgsize_bitmap; +}; + +struct hv_pci_busdata { + int pci_domain_nr; + u32 logical_dev_id_prefix; + struct list_head list; +}; + +struct hv_iommu_endpoint { + struct device *dev; + struct hv_iommu_dev *hv_iommu; + struct hv_iommu_domain *hv_domain; +}; + +#define to_hv_iommu_domain(d) \ + container_of(d, struct hv_iommu_domain, domain) + +#endif /* _HYPERV_IOMMU_H */ diff --git a/drivers/pci/controller/pci-hyperv.c b/drivers/pci/controller/pci-hyperv.c index cfc8fa403dad..a4af9c8c2220 100644 --- a/drivers/pci/controller/pci-hyperv.c +++ b/drivers/pci/controller/pci-hyperv.c @@ -3715,6 +3715,7 @@ static int hv_pci_probe(struct hv_device *hdev, struct hv_pcibus_device *hbus; int ret, dom; u16 dom_req; + u32 prefix; char *name; bridge = devm_pci_alloc_host_bridge(&hdev->device, 0); @@ -3857,13 +3858,25 @@ static int hv_pci_probe(struct hv_device *hdev, hbus->state = hv_pcibus_probed; - ret = create_root_hv_pci_bus(hbus); + /* Notify pvIOMMU before any device on the bus is scanned. */ + prefix = (hdev->dev_instance.b[5] << 24) | + (hdev->dev_instance.b[4] << 16) | + (hdev->dev_instance.b[7] << 8) | + (hdev->dev_instance.b[6] & 0xf8); + + ret = hv_iommu_register_pci_bus(dom, prefix); if (ret) goto free_windows; + ret = create_root_hv_pci_bus(hbus); + if (ret) + goto unregister_pviommu; + mutex_unlock(&hbus->state_lock); return 0; +unregister_pviommu: + hv_iommu_unregister_pci_bus(dom); free_windows: hv_pci_free_bridge_windows(hbus); exit_d0: @@ -3974,8 +3987,10 @@ static int hv_pci_bus_exit(struct hv_device *hdev, bool keep_devs) static void hv_pci_remove(struct hv_device *hdev) { struct hv_pcibus_device *hbus; + int dom; hbus = hv_get_drvdata(hdev); + dom = hbus->bridge->domain_nr; if (hbus->state == hv_pcibus_installed) { tasklet_disable(&hdev->channel->callback_event); hbus->state = hv_pcibus_removing; @@ -3994,6 +4009,8 @@ static void hv_pci_remove(struct hv_device *hdev) hv_pci_remove_slots(hbus); pci_remove_root_bus(hbus->bridge->bus); pci_unlock_rescan_remove(); + + hv_iommu_unregister_pci_bus(dom); } hv_pci_bus_exit(hdev, false); diff --git a/include/asm-generic/mshyperv.h b/include/asm-generic/mshyperv.h index bf601d67cecb..b71345c74568 100644 --- a/include/asm-generic/mshyperv.h +++ b/include/asm-generic/mshyperv.h @@ -73,6 +73,18 @@ extern enum hv_partition_type hv_curr_partition_type; extern void * __percpu *hyperv_pcpu_input_arg; extern void * __percpu *hyperv_pcpu_output_arg; +#ifdef CONFIG_HYPERV_PVIOMMU +int hv_iommu_register_pci_bus(int pci_domain_nr, u32 logical_dev_id_prefix); +void hv_iommu_unregister_pci_bus(int pci_domain_nr); +#else +static inline int hv_iommu_register_pci_bus(int pci_domain_nr, + u32 logical_dev_id_prefix) +{ + return 0; +} +static inline void hv_iommu_unregister_pci_bus(int pci_domain_nr) { } +#endif + u64 hv_do_hypercall(u64 control, void *inputaddr, void *outputaddr); u64 hv_do_fast_hypercall8(u16 control, u64 input8); u64 hv_do_fast_hypercall16(u16 control, u64 input1, u64 input2); -- 2.52.0 ^ permalink raw reply related [flat|nested] 6+ messages in thread
* Re: [PATCH v1 3/4] iommu/hyperv: Add para-virtualized IOMMU support for Hyper-V guest 2026-05-11 16:24 ` [PATCH v1 3/4] iommu/hyperv: Add para-virtualized IOMMU support for Hyper-V guest Yu Zhang @ 2026-05-13 18:39 ` Jacob Pan 0 siblings, 0 replies; 6+ messages in thread From: Jacob Pan @ 2026-05-13 18:39 UTC (permalink / raw) To: Yu Zhang Cc: linux-kernel, linux-hyperv, iommu, linux-pci, linux-arch, wei.liu, kys, haiyangz, decui, longli, joro, will, robin.murphy, bhelgaas, kwilczynski, lpieralisi, mani, robh, arnd, jgg, mhklinux, tgopinath, easwar.hariharan, jacob.pan Hi Yu, On Tue, 12 May 2026 00:24:07 +0800 Yu Zhang <zhangyu1@linux.microsoft.com> wrote: > Add a para-virtualized IOMMU driver for Linux guests running on > Hyper-V. This driver implements stage-1 IO translation within the > guest OS. It integrates with the Linux IOMMU core, utilizing Hyper-V > hypercalls for: > - Capability discovery > - Domain allocation, configuration, and deallocation > - Device attachment and detachment > - IOTLB invalidation > > The driver constructs x86-compatible stage-1 IO page tables in the > guest memory using consolidated IO page table helpers. This allows > the guest to manage stage-1 translations independently of vendor- > specific drivers (like Intel VT-d or AMD IOMMU). > > Hyper-V consumes this stage-1 IO page table when a device domain is > created and configured, and nests it with the host's stage-2 IO page > tables, therefore eliminating the VM exits for guest IOMMU mapping > operations. For unmapping operations, VM exits to perform the IOTLB > flush are still unavoidable. > > Hyper-V identifies each PCI pass-thru device by a logical device ID > in its hypercall interface. The vPCI driver (pci-hyperv) registers the > per-bus portion of this ID with the pvIOMMU driver during bus probe. > The pvIOMMU driver stores this mapping and combines it with the > function number of the endpoint PCI device to form the complete ID > for hypercalls. > > Co-developed-by: Wei Liu <wei.liu@kernel.org> > Signed-off-by: Wei Liu <wei.liu@kernel.org> > Co-developed-by: Easwar Hariharan > <easwar.hariharan@linux.microsoft.com> Signed-off-by: Easwar > Hariharan <easwar.hariharan@linux.microsoft.com> Signed-off-by: Yu > Zhang <zhangyu1@linux.microsoft.com> --- > arch/x86/hyperv/hv_init.c | 4 + > arch/x86/include/asm/mshyperv.h | 4 + > drivers/iommu/hyperv/Kconfig | 17 + > drivers/iommu/hyperv/Makefile | 1 + > drivers/iommu/hyperv/iommu.c | 705 > ++++++++++++++++++++++++++++ drivers/iommu/hyperv/iommu.h | > 54 +++ drivers/pci/controller/pci-hyperv.c | 19 +- > include/asm-generic/mshyperv.h | 12 + > 8 files changed, 815 insertions(+), 1 deletion(-) > create mode 100644 drivers/iommu/hyperv/iommu.c > create mode 100644 drivers/iommu/hyperv/iommu.h > > diff --git a/arch/x86/hyperv/hv_init.c b/arch/x86/hyperv/hv_init.c > index 323adc93f2dc..2c8ff8e06249 100644 > --- a/arch/x86/hyperv/hv_init.c > +++ b/arch/x86/hyperv/hv_init.c > @@ -578,6 +578,10 @@ void __init hyperv_init(void) > old_setup_percpu_clockev = > x86_init.timers.setup_percpu_clockev; > x86_init.timers.setup_percpu_clockev = > hv_stimer_setup_percpu_clockev; +#ifdef CONFIG_HYPERV_PVIOMMU > + x86_init.iommu.iommu_init = hv_iommu_init; > +#endif > + > hv_apic_init(); > > x86_init.pci.arch_init = hv_pci_init; > diff --git a/arch/x86/include/asm/mshyperv.h > b/arch/x86/include/asm/mshyperv.h index f64393e853ee..20d947c2c758 > 100644 --- a/arch/x86/include/asm/mshyperv.h > +++ b/arch/x86/include/asm/mshyperv.h > @@ -313,6 +313,10 @@ static inline void > mshv_vtl_return_hypercall(void) {} static inline void > __mshv_vtl_return_call(struct mshv_vtl_cpu_context *vtl0) {} #endif > > +#ifdef CONFIG_HYPERV_PVIOMMU > +int __init hv_iommu_init(void); > +#endif > + > #include <asm-generic/mshyperv.h> > > #endif > diff --git a/drivers/iommu/hyperv/Kconfig > b/drivers/iommu/hyperv/Kconfig index 30f40d867036..9e658d5c9a77 100644 > --- a/drivers/iommu/hyperv/Kconfig > +++ b/drivers/iommu/hyperv/Kconfig > @@ -8,3 +8,20 @@ config HYPERV_IOMMU > help > Stub IOMMU driver to handle IRQs to support Hyper-V Linux > guest and root partitions. > + > +if HYPERV_IOMMU > +config HYPERV_PVIOMMU > + bool "Microsoft Hypervisor para-virtualized IOMMU support" > + depends on X86 && HYPERV > + select IOMMU_API > + select GENERIC_PT > + select IOMMU_PT > + select IOMMU_PT_X86_64 nit: If HYPERV_PVIOMMU is enabled on a (hypothetical) platform with GENERIC_ATOMIC64=y, the select would force-enable IOMMU_PT_X86_64 even though its depends on is unsatisfied — leading to a build failure. In practice this can't happen today because HYPERV_PVIOMMU already depends on X86 && HYPERV, and x86 never sets GENERIC_ATOMIC64. But adding the explicit guard is more defensive. i.e. depends on !GENERIC_ATOMIC64 # for cmpxchg64 in IOMMU_PT > + select IOMMU_IOVA > + default HYPERV > + help > + Para-virtualized IOMMU driver for Linux guests running on > + Microsoft Hyper-V. Provides DMA remapping and IOTLB > + flush support to enable DMA isolation for devices > + assigned to the guest. > +endif > diff --git a/drivers/iommu/hyperv/Makefile > b/drivers/iommu/hyperv/Makefile index 9f557bad94ff..8669741c0a51 > 100644 --- a/drivers/iommu/hyperv/Makefile > +++ b/drivers/iommu/hyperv/Makefile > @@ -1,2 +1,3 @@ > # SPDX-License-Identifier: GPL-2.0 > obj-$(CONFIG_HYPERV_IOMMU) += irq_remapping.o > +obj-$(CONFIG_HYPERV_PVIOMMU) += iommu.o > diff --git a/drivers/iommu/hyperv/iommu.c > b/drivers/iommu/hyperv/iommu.c new file mode 100644 > index 000000000000..e5fc625314b5 > --- /dev/null > +++ b/drivers/iommu/hyperv/iommu.c > @@ -0,0 +1,705 @@ > +// SPDX-License-Identifier: GPL-2.0 > + > +/* > + * Hyper-V IOMMU driver. > + * > + * Copyright (C) 2019, 2024-2026 Microsoft, Inc. > + */ > + > +#define pr_fmt(fmt) "Hyper-V pvIOMMU: " fmt > +#define dev_fmt(fmt) pr_fmt(fmt) > + > +#include <linux/iommu.h> > +#include <linux/pci.h> > +#include <linux/dma-map-ops.h> > +#include <linux/generic_pt/iommu.h> > +#include <linux/pci-ats.h> > + > +#include <asm/iommu.h> > +#include <asm/hypervisor.h> > +#include <asm/mshyperv.h> > + > +#include "iommu.h" > +#include "../iommu-pages.h" > + > +struct hv_iommu_dev *hv_iommu_device; > + > +/* > + * Identity and blocking domains are static singletons: identity is > a 1:1 > + * passthrough with no page table, blocking rejects all DMA. Neither > holds > + * per-IOMMU state, so one instance suffices even with multiple > vIOMMUs. > + */ > +static struct hv_iommu_domain hv_identity_domain; > +static struct hv_iommu_domain hv_blocking_domain; > +static const struct iommu_domain_ops hv_iommu_identity_domain_ops; > +static const struct iommu_domain_ops hv_iommu_blocking_domain_ops; > +static struct iommu_ops hv_iommu_ops; > +static LIST_HEAD(hv_iommu_pci_bus_list); > +static DEFINE_SPINLOCK(hv_iommu_pci_bus_lock); > + > +#define hv_iommu_present(iommu_cap) (iommu_cap & > HV_IOMMU_CAP_PRESENT) +#define > hv_iommu_s1_domain_supported(iommu_cap) (iommu_cap & HV_IOMMU_CAP_S1) > +#define hv_iommu_5lvl_supported(iommu_cap) (iommu_cap & > HV_IOMMU_CAP_S1_5LVL) +#define hv_iommu_ats_supported(iommu_cap) > (iommu_cap & HV_IOMMU_CAP_ATS) + +int hv_iommu_register_pci_bus(int > pci_domain_nr, u32 logical_dev_id_prefix) +{ > + struct hv_pci_busdata *bus, *new; > + int ret = 0; > + > + if (no_iommu || !iommu_detected) > + return 0; > + > + new = kzalloc_obj(*new, GFP_KERNEL); > + if (!new) > + return -ENOMEM; > + > + spin_lock(&hv_iommu_pci_bus_lock); > + list_for_each_entry(bus, &hv_iommu_pci_bus_list, list) { > + if (bus->pci_domain_nr != pci_domain_nr) > + continue; > + > + if (bus->logical_dev_id_prefix != > logical_dev_id_prefix) { > + pr_err("stale registration for PCI domain %d > (old prefix 0x%08x, new 0x%08x)\n", > + pci_domain_nr, > bus->logical_dev_id_prefix, > + logical_dev_id_prefix); > + ret = -EEXIST; > + } > + > + goto out_free; > + } > + > + new->pci_domain_nr = pci_domain_nr; > + new->logical_dev_id_prefix = logical_dev_id_prefix; > + list_add(&new->list, &hv_iommu_pci_bus_list); > + spin_unlock(&hv_iommu_pci_bus_lock); > + return 0; > + > +out_free: > + spin_unlock(&hv_iommu_pci_bus_lock); > + kfree(new); > + return ret; > +} > +EXPORT_SYMBOL_FOR_MODULES(hv_iommu_register_pci_bus, "pci-hyperv"); > + > +void hv_iommu_unregister_pci_bus(int pci_domain_nr) > +{ > + struct hv_pci_busdata *bus, *tmp; > + > + spin_lock(&hv_iommu_pci_bus_lock); > + list_for_each_entry_safe(bus, tmp, &hv_iommu_pci_bus_list, > list) { > + if (bus->pci_domain_nr == pci_domain_nr) { > + list_del(&bus->list); > + kfree(bus); > + break; > + } > + } > + spin_unlock(&hv_iommu_pci_bus_lock); > +} > +EXPORT_SYMBOL_FOR_MODULES(hv_iommu_unregister_pci_bus, "pci-hyperv"); > + > +/* > + * Look up the logical device ID for a vPCI device. Returns 0 on > success > + * with *logical_id filled in; -ENODEV if no entry registered for > this > + * device's vPCI bus. > + */ > +static int hv_iommu_lookup_logical_dev_id(struct pci_dev *pdev, u64 > *logical_id) +{ > + struct hv_pci_busdata *bus; > + int domain = pci_domain_nr(pdev->bus); > + int ret = -ENODEV; > + > + spin_lock(&hv_iommu_pci_bus_lock); this is called under local_irq_save, should use raw_spinlock_t for RT kernel? > + list_for_each_entry(bus, &hv_iommu_pci_bus_list, list) { > + if (bus->pci_domain_nr == domain) { > + *logical_id = > (u64)bus->logical_dev_id_prefix | > + PCI_FUNC(pdev->devfn); > + ret = 0; > + break; > + } > + } > + spin_unlock(&hv_iommu_pci_bus_lock); > + return ret; > +} > + > +static int hv_create_device_domain(struct hv_iommu_domain > *hv_domain, u32 domain_stage) +{ > + int ret; > + u64 status; > + unsigned long flags; > + struct hv_input_create_device_domain *input; > + > + ret = ida_alloc_range(&hv_iommu_device->domain_ids, > + hv_iommu_device->first_domain, > hv_iommu_device->last_domain, > + GFP_KERNEL); > + if (ret < 0) > + return ret; > + > + hv_domain->device_domain.partition_id = HV_PARTITION_ID_SELF; > + hv_domain->device_domain.domain_id.type = domain_stage; > + hv_domain->device_domain.domain_id.id = ret; > + hv_domain->hv_iommu = hv_iommu_device; > + > + local_irq_save(flags); > + > + input = *this_cpu_ptr(hyperv_pcpu_input_arg); > + memset(input, 0, sizeof(*input)); > + input->device_domain = hv_domain->device_domain; > + input->create_device_domain_flags.forward_progress_required > = 1; > + input->create_device_domain_flags.inherit_owning_vtl = 0; > + status = hv_do_hypercall(HVCALL_CREATE_DEVICE_DOMAIN, input, > NULL); + > + local_irq_restore(flags); > + > + if (!hv_result_success(status)) { > + pr_err("HVCALL_CREATE_DEVICE_DOMAIN failed, status > %lld\n", status); > + ida_free(&hv_iommu_device->domain_ids, > hv_domain->device_domain.domain_id.id); > + } > + > + return hv_result_to_errno(status); > +} > + > +static void hv_delete_device_domain(struct hv_iommu_domain > *hv_domain) +{ > + u64 status; > + unsigned long flags; > + struct hv_input_delete_device_domain *input; > + > + local_irq_save(flags); > + > + input = *this_cpu_ptr(hyperv_pcpu_input_arg); > + memset(input, 0, sizeof(*input)); > + input->device_domain = hv_domain->device_domain; > + status = hv_do_hypercall(HVCALL_DELETE_DEVICE_DOMAIN, input, > NULL); + > + local_irq_restore(flags); > + > + if (!hv_result_success(status)) > + pr_err("HVCALL_DELETE_DEVICE_DOMAIN failed, status > %lld\n", status); + > + ida_free(&hv_domain->hv_iommu->domain_ids, > hv_domain->device_domain.domain_id.id); +} > + > +static bool hv_iommu_capable(struct device *dev, enum iommu_cap cap) > +{ > + switch (cap) { > + case IOMMU_CAP_CACHE_COHERENCY: > + return true; > + case IOMMU_CAP_DEFERRED_FLUSH: > + return true; > + default: > + return false; > + } > +} > + > +static void hv_flush_device_domain(struct hv_iommu_domain *hv_domain) > +{ > + u64 status; > + unsigned long flags; > + struct hv_input_flush_device_domain *input; > + > + local_irq_save(flags); > + > + input = *this_cpu_ptr(hyperv_pcpu_input_arg); > + memset(input, 0, sizeof(*input)); > + input->device_domain = hv_domain->device_domain; > + status = hv_do_hypercall(HVCALL_FLUSH_DEVICE_DOMAIN, input, > NULL); + > + local_irq_restore(flags); > + > + if (!hv_result_success(status)) > + pr_err("HVCALL_FLUSH_DEVICE_DOMAIN failed, status > %lld\n", status); +} > + > +static void hv_iommu_detach_dev(struct iommu_domain *domain, struct > device *dev) +{ > + u64 status; > + unsigned long flags; > + struct hv_input_detach_device_domain *input; > + struct pci_dev *pdev; > + struct hv_iommu_domain *hv_domain = > to_hv_iommu_domain(domain); > + struct hv_iommu_endpoint *vdev = dev_iommu_priv_get(dev); > + > + /* See the attach function, only PCI devices for now */ > + if (!dev_is_pci(dev) || vdev->hv_domain != hv_domain) > + return; > + > + pdev = to_pci_dev(dev); > + > + dev_dbg(dev, "detaching from domain %d\n", > hv_domain->device_domain.domain_id.id); + > + local_irq_save(flags); > + > + input = *this_cpu_ptr(hyperv_pcpu_input_arg); > + memset(input, 0, sizeof(*input)); > + input->partition_id = HV_PARTITION_ID_SELF; > + if (hv_iommu_lookup_logical_dev_id(pdev, > &input->device_id.as_uint64)) { > + local_irq_restore(flags); > + dev_warn(&pdev->dev, "no IOMMU registration for vPCI > bus on detach\n"); > + return; > + } > + status = hv_do_hypercall(HVCALL_DETACH_DEVICE_DOMAIN, input, > NULL); + > + local_irq_restore(flags); > + > + if (!hv_result_success(status)) > + pr_err("HVCALL_DETACH_DEVICE_DOMAIN failed, status > %lld\n", status); + > + hv_flush_device_domain(hv_domain); > + > + vdev->hv_domain = NULL; > +} > + > +static int hv_iommu_attach_dev(struct iommu_domain *domain, struct > device *dev, > + struct iommu_domain *old) > +{ > + u64 status; > + unsigned long flags; > + struct pci_dev *pdev; > + struct hv_input_attach_device_domain *input; > + struct hv_iommu_endpoint *vdev = dev_iommu_priv_get(dev); > + struct hv_iommu_domain *hv_domain = > to_hv_iommu_domain(domain); > + int ret; > + > + /* Only allow PCI devices for now */ > + if (!dev_is_pci(dev)) > + return -EINVAL; > + > + if (vdev->hv_domain == hv_domain) > + return 0; > + > + if (vdev->hv_domain) > + hv_iommu_detach_dev(&vdev->hv_domain->domain, dev); > + > + pdev = to_pci_dev(dev); > + dev_dbg(dev, "attaching to domain %d\n", > + hv_domain->device_domain.domain_id.id); > + > + local_irq_save(flags); > + > + input = *this_cpu_ptr(hyperv_pcpu_input_arg); > + memset(input, 0, sizeof(*input)); > + input->device_domain = hv_domain->device_domain; > + ret = hv_iommu_lookup_logical_dev_id(pdev, > &input->device_id.as_uint64); > + if (ret) { > + local_irq_restore(flags); > + dev_err(&pdev->dev, "no IOMMU registration for vPCI > bus\n"); > + return ret; > + } > + status = hv_do_hypercall(HVCALL_ATTACH_DEVICE_DOMAIN, input, > NULL); + > + local_irq_restore(flags); > + > + if (!hv_result_success(status)) > + pr_err("HVCALL_ATTACH_DEVICE_DOMAIN failed, status > %lld\n", status); > + else > + vdev->hv_domain = hv_domain; > + > + return hv_result_to_errno(status); > +} > + > +static int hv_iommu_get_logical_device_property(struct device *dev, > + u32 code, > + struct > hv_output_get_logical_device_property *property) +{ > + u64 status, lid; > + unsigned long flags; > + int ret; > + struct hv_input_get_logical_device_property *input; > + struct hv_output_get_logical_device_property *output; > + > + local_irq_save(flags); > + > + input = *this_cpu_ptr(hyperv_pcpu_input_arg); > + output = *this_cpu_ptr(hyperv_pcpu_input_arg) + > sizeof(*input); > + memset(input, 0, sizeof(*input)); > + input->partition_id = HV_PARTITION_ID_SELF; > + ret = hv_iommu_lookup_logical_dev_id(to_pci_dev(dev), &lid); > + if (ret) { > + local_irq_restore(flags); > + return ret; > + } > + input->logical_device_id = lid; > + input->code = code; > + status = hv_do_hypercall(HVCALL_GET_LOGICAL_DEVICE_PROPERTY, > input, output); > + *property = *output; > + > + local_irq_restore(flags); > + > + if (!hv_result_success(status)) > + pr_err("HVCALL_GET_LOGICAL_DEVICE_PROPERTY failed, > status %lld\n", status); + > + return hv_result_to_errno(status); > +} > + > +static struct iommu_device *hv_iommu_probe_device(struct device *dev) > +{ > + struct pci_dev *pdev; > + struct hv_iommu_endpoint *vdev; > + struct hv_output_get_logical_device_property > device_iommu_property = {0}; + > + if (!dev_is_pci(dev)) > + return ERR_PTR(-ENODEV); > + > + pdev = to_pci_dev(dev); > + > + if (hv_iommu_get_logical_device_property(dev, > + > HV_LOGICAL_DEVICE_PROPERTY_PVIOMMU, > + > &device_iommu_property) || > + !(device_iommu_property.device_iommu & > HV_DEVICE_IOMMU_ENABLED)) > + return ERR_PTR(-ENODEV); > + > + vdev = kzalloc_obj(*vdev, GFP_KERNEL); > + if (!vdev) > + return ERR_PTR(-ENOMEM); > + > + vdev->dev = dev; > + vdev->hv_iommu = hv_iommu_device; > + dev_iommu_priv_set(dev, vdev); > + > + if (hv_iommu_ats_supported(hv_iommu_device->cap) && > + pci_ats_supported(pdev)) > + pci_enable_ats(pdev, > __ffs(hv_iommu_device->pgsize_bitmap)); + > + return &vdev->hv_iommu->iommu; > +} > + > +static void hv_iommu_release_device(struct device *dev) > +{ > + struct hv_iommu_endpoint *vdev = dev_iommu_priv_get(dev); > + struct pci_dev *pdev = to_pci_dev(dev); > + > + if (pdev->ats_enabled) > + pci_disable_ats(pdev); > + > + dev_iommu_priv_set(dev, NULL); > + set_dma_ops(dev, NULL); I don't think this is necessary. > + > + kfree(vdev); > +} > + > +static struct iommu_group *hv_iommu_device_group(struct device *dev) > +{ > + if (dev_is_pci(dev)) > + return pci_device_group(dev); > + else > + return generic_device_group(dev); non pci device already rejected during attach, maybe we should warn here? WARN_ON_ONCE(1); return generic_device_group(dev); > +} > + > +static int hv_configure_device_domain(struct hv_iommu_domain > *hv_domain, u32 domain_type) +{ > + u64 status; > + unsigned long flags; > + struct pt_iommu_x86_64_hw_info pt_info; > + struct hv_input_configure_device_domain *input; > + > + local_irq_save(flags); > + > + input = *this_cpu_ptr(hyperv_pcpu_input_arg); > + memset(input, 0, sizeof(*input)); > + input->device_domain = hv_domain->device_domain; > + input->settings.flags.blocked = (domain_type == > IOMMU_DOMAIN_BLOCKED); > + input->settings.flags.translation_enabled = (domain_type != > IOMMU_DOMAIN_IDENTITY); + Should this be: input->settings.flags.translation_enabled = (domain_type & __IOMMU_DOMAIN_PAGING); Otherwise, blocked domain will have translation enabled. Maybe add some explanation of what HV expects. > + if (domain_type & __IOMMU_DOMAIN_PAGING) { > + pt_iommu_x86_64_hw_info(&hv_domain->pt_iommu_x86_64, > &pt_info); > + input->settings.page_table_root = pt_info.gcr3_pt; > + input->settings.flags.first_stage_paging_mode = > + pt_info.levels == 5; > + } > + status = hv_do_hypercall(HVCALL_CONFIGURE_DEVICE_DOMAIN, > input, NULL); + > + local_irq_restore(flags); > + > + if (!hv_result_success(status)) > + pr_err("HVCALL_CONFIGURE_DEVICE_DOMAIN failed, > status %lld\n", status); + > + return hv_result_to_errno(status); > +} > + > +static int __init hv_initialize_static_domains(void) > +{ > + int ret; > + struct hv_iommu_domain *hv_domain; > + > + /* Default stage-1 identity domain */ > + hv_domain = &hv_identity_domain; > + > + ret = hv_create_device_domain(hv_domain, > HV_DEVICE_DOMAIN_TYPE_S1); > + if (ret) > + return ret; > + > + ret = hv_configure_device_domain(hv_domain, > IOMMU_DOMAIN_IDENTITY); > + if (ret) > + goto delete_identity_domain; > + > + hv_domain->domain.type = IOMMU_DOMAIN_IDENTITY; > + hv_domain->domain.ops = &hv_iommu_identity_domain_ops; > + hv_domain->domain.owner = &hv_iommu_ops; > + hv_domain->domain.geometry = hv_iommu_device->geometry; > + hv_domain->domain.pgsize_bitmap = > hv_iommu_device->pgsize_bitmap; + > + /* Default stage-1 blocked domain */ > + hv_domain = &hv_blocking_domain; > + > + ret = hv_create_device_domain(hv_domain, > HV_DEVICE_DOMAIN_TYPE_S1); > + if (ret) > + goto delete_identity_domain; > + > + ret = hv_configure_device_domain(hv_domain, > IOMMU_DOMAIN_BLOCKED); > + if (ret) > + goto delete_blocked_domain; > + > + hv_domain->domain.type = IOMMU_DOMAIN_BLOCKED; > + hv_domain->domain.ops = &hv_iommu_blocking_domain_ops; > + hv_domain->domain.owner = &hv_iommu_ops; > + hv_domain->domain.geometry = hv_iommu_device->geometry; > + hv_domain->domain.pgsize_bitmap = > hv_iommu_device->pgsize_bitmap; + > + return 0; > + > +delete_blocked_domain: > + hv_delete_device_domain(&hv_blocking_domain); > +delete_identity_domain: > + hv_delete_device_domain(&hv_identity_domain); > + return ret; > +} > + > +#define INTERRUPT_RANGE_START (0xfee00000) > +#define INTERRUPT_RANGE_END (0xfeefffff) > +static void hv_iommu_get_resv_regions(struct device *dev, > + struct list_head *head) > +{ > + struct iommu_resv_region *region; > + > + region = iommu_alloc_resv_region(INTERRUPT_RANGE_START, > + INTERRUPT_RANGE_END - > INTERRUPT_RANGE_START + 1, > + 0, IOMMU_RESV_MSI, GFP_KERNEL); > + if (!region) > + return; > + > + list_add_tail(®ion->list, head); > +} > + > +static void hv_iommu_flush_iotlb_all(struct iommu_domain *domain) > +{ > + hv_flush_device_domain(to_hv_iommu_domain(domain)); > +} > + > +static void hv_iommu_iotlb_sync(struct iommu_domain *domain, > + struct iommu_iotlb_gather > *iotlb_gather) +{ > + hv_flush_device_domain(to_hv_iommu_domain(domain)); > + > + iommu_put_pages_list(&iotlb_gather->freelist); > +} > + > +static void hv_iommu_paging_domain_free(struct iommu_domain *domain) > +{ > + struct hv_iommu_domain *hv_domain = > to_hv_iommu_domain(domain); + > + /* Free all remaining mappings */ > + pt_iommu_deinit(&hv_domain->pt_iommu); > + > + hv_delete_device_domain(hv_domain); > + > + kfree(hv_domain); > +} > + > +static const struct iommu_domain_ops hv_iommu_identity_domain_ops = { > + .attach_dev = hv_iommu_attach_dev, > +}; > + > +static const struct iommu_domain_ops hv_iommu_blocking_domain_ops = { > + .attach_dev = hv_iommu_attach_dev, > +}; > + > +static const struct iommu_domain_ops hv_iommu_paging_domain_ops = { > + .attach_dev = hv_iommu_attach_dev, > + IOMMU_PT_DOMAIN_OPS(x86_64), > + .flush_iotlb_all = hv_iommu_flush_iotlb_all, > + .iotlb_sync = hv_iommu_iotlb_sync, > + .free = hv_iommu_paging_domain_free, > +}; > + > +static struct iommu_domain *hv_iommu_domain_alloc_paging(struct > device *dev) +{ > + int ret; > + struct hv_iommu_domain *hv_domain; > + struct pt_iommu_x86_64_cfg cfg = {}; > + > + hv_domain = kzalloc_obj(*hv_domain, GFP_KERNEL); > + if (!hv_domain) > + return ERR_PTR(-ENOMEM); > + > + ret = hv_create_device_domain(hv_domain, > HV_DEVICE_DOMAIN_TYPE_S1); > + if (ret) { > + kfree(hv_domain); > + return ERR_PTR(ret); > + } > + > + hv_domain->domain.geometry = hv_iommu_device->geometry; > + hv_domain->pt_iommu.nid = dev_to_node(dev); > + > + cfg.common.hw_max_vasz_lg2 = hv_iommu_device->max_iova_width; > + cfg.common.hw_max_oasz_lg2 = 52; > + cfg.top_level = (hv_iommu_device->max_iova_width > 48) ? 4 : > 3; + > + ret = pt_iommu_x86_64_init(&hv_domain->pt_iommu_x86_64, > &cfg, GFP_KERNEL); > + if (ret) { > + hv_delete_device_domain(hv_domain); > + kfree(hv_domain); > + return ERR_PTR(ret); > + } > + > + /* Constrain to page sizes the hypervisor supports */ > + hv_domain->domain.pgsize_bitmap &= > hv_iommu_device->pgsize_bitmap; + > + hv_domain->domain.ops = &hv_iommu_paging_domain_ops; > + > + ret = hv_configure_device_domain(hv_domain, > __IOMMU_DOMAIN_PAGING); > + if (ret) { > + pt_iommu_deinit(&hv_domain->pt_iommu); > + hv_delete_device_domain(hv_domain); > + kfree(hv_domain); > + return ERR_PTR(ret); > + } > + > + return &hv_domain->domain; > +} > + > +static struct iommu_ops hv_iommu_ops = { > + .capable = hv_iommu_capable, > + .domain_alloc_paging = hv_iommu_domain_alloc_paging, > + .probe_device = hv_iommu_probe_device, > + .release_device = hv_iommu_release_device, > + .device_group = hv_iommu_device_group, > + .get_resv_regions = hv_iommu_get_resv_regions, > + .owner = THIS_MODULE, > + .identity_domain = &hv_identity_domain.domain, > + .blocked_domain = > &hv_blocking_domain.domain, > + .release_domain = > &hv_blocking_domain.domain, +}; > + > +static int hv_iommu_detect(struct hv_output_get_iommu_capabilities > *hv_iommu_cap) +{ > + u64 status; > + unsigned long flags; > + struct hv_input_get_iommu_capabilities *input; > + struct hv_output_get_iommu_capabilities *output; > + > + local_irq_save(flags); > + > + input = *this_cpu_ptr(hyperv_pcpu_input_arg); > + output = *this_cpu_ptr(hyperv_pcpu_input_arg) + > sizeof(*input); > + memset(input, 0, sizeof(*input)); > + input->partition_id = HV_PARTITION_ID_SELF; > + status = hv_do_hypercall(HVCALL_GET_IOMMU_CAPABILITIES, > input, output); > + *hv_iommu_cap = *output; > + > + local_irq_restore(flags); > + > + if (!hv_result_success(status)) > + pr_err("HVCALL_GET_IOMMU_CAPABILITIES failed, status > %lld\n", status); + > + return hv_result_to_errno(status); > +} > + > +static void __init hv_init_iommu_device(struct hv_iommu_dev > *hv_iommu, > + struct hv_output_get_iommu_capabilities > *hv_iommu_cap) +{ > + ida_init(&hv_iommu->domain_ids); > + > + hv_iommu->cap = hv_iommu_cap->iommu_cap; > + hv_iommu->max_iova_width = hv_iommu_cap->max_iova_width; > + if (!hv_iommu_5lvl_supported(hv_iommu->cap) && > + hv_iommu->max_iova_width > 48) { > + pr_info("5-level paging not supported, limiting iova > width to 48.\n"); > + hv_iommu->max_iova_width = 48; > + } > + > + hv_iommu->geometry = (struct iommu_domain_geometry) { > + .aperture_start = 0, > + .aperture_end = (((u64)1) << > hv_iommu->max_iova_width) - 1, > + .force_aperture = true, > + }; > + > + hv_iommu->first_domain = HV_DEVICE_DOMAIN_ID_DEFAULT + 1; > + hv_iommu->last_domain = HV_DEVICE_DOMAIN_ID_NULL - 1; > + /* Only x86 page sizes (4K/2M/1G) are supported */ > + hv_iommu->pgsize_bitmap = hv_iommu_cap->pgsize_bitmap & > + (SZ_4K | SZ_2M | SZ_1G); > + if (hv_iommu->pgsize_bitmap != hv_iommu_cap->pgsize_bitmap) > + pr_warn("unsupported page sizes masked: 0x%llx -> > 0x%llx\n", > + hv_iommu_cap->pgsize_bitmap, > hv_iommu->pgsize_bitmap); > + if (!hv_iommu->pgsize_bitmap) { > + pr_warn("no supported page sizes, defaulting to > 4K\n"); > + hv_iommu->pgsize_bitmap = SZ_4K; > + } > + hv_iommu_device = hv_iommu; > +} > + > +int __init hv_iommu_init(void) > +{ > + int ret = 0; > + struct hv_iommu_dev *hv_iommu = NULL; > + struct hv_output_get_iommu_capabilities hv_iommu_cap = {0}; > + > + if (no_iommu || iommu_detected) > + return -ENODEV; > + > + if (!hv_is_hyperv_initialized()) > + return -ENODEV; > + > + ret = hv_iommu_detect(&hv_iommu_cap); > + if (ret) { > + pr_err("HVCALL_GET_IOMMU_CAPABILITIES failed: %d\n", > ret); > + return -ENODEV; > + } > + > + if (!hv_iommu_present(hv_iommu_cap.iommu_cap) || > + !hv_iommu_s1_domain_supported(hv_iommu_cap.iommu_cap)) { > + pr_err("IOMMU capabilities not sufficient: > cap=0x%llx\n", > + hv_iommu_cap.iommu_cap); > + return -ENODEV; > + } > + > + iommu_detected = 1; > + pci_request_acs(); > + > + hv_iommu = kzalloc_obj(*hv_iommu, GFP_KERNEL); > + if (!hv_iommu) > + return -ENOMEM; > + > + hv_init_iommu_device(hv_iommu, &hv_iommu_cap); > + > + ret = hv_initialize_static_domains(); > + if (ret) { > + pr_err("static domains init failed: %d\n", ret); > + goto err_free; > + } > + > + ret = iommu_device_sysfs_add(&hv_iommu->iommu, NULL, NULL, > "%s", "hv-iommu"); > + if (ret) { > + pr_err("iommu_device_sysfs_add failed: %d\n", ret); > + goto err_delete_static_domains; > + } > + > + ret = iommu_device_register(&hv_iommu->iommu, &hv_iommu_ops, > NULL); > + if (ret) { > + pr_err("iommu_device_register failed: %d\n", ret); > + goto err_sysfs_remove; > + } > + > + pr_info("successfully initialized\n"); > + return 0; > + > +err_sysfs_remove: > + iommu_device_sysfs_remove(&hv_iommu->iommu); > +err_delete_static_domains: > + hv_delete_device_domain(&hv_blocking_domain); > + hv_delete_device_domain(&hv_identity_domain); > +err_free: > + kfree(hv_iommu); > + return ret; > +} > diff --git a/drivers/iommu/hyperv/iommu.h > b/drivers/iommu/hyperv/iommu.h new file mode 100644 > index 000000000000..43f20d371245 > --- /dev/null > +++ b/drivers/iommu/hyperv/iommu.h > @@ -0,0 +1,54 @@ > +/* SPDX-License-Identifier: GPL-2.0 */ > + > +/* > + * Hyper-V IOMMU driver. > + * > + * Copyright (C) 2024-2025, Microsoft, Inc. > + * > + */ > + > +#ifndef _HYPERV_IOMMU_H > +#define _HYPERV_IOMMU_H > + > +struct hv_iommu_dev { > + struct iommu_device iommu; > + struct ida domain_ids; > + > + /* Device configuration */ > + u8 max_iova_width; > + u8 max_pasid_width; > + u64 cap; > + u64 pgsize_bitmap; > + > + struct iommu_domain_geometry geometry; > + u64 first_domain; > + u64 last_domain; > +}; > + > +struct hv_iommu_domain { > + union { > + struct iommu_domain domain; > + struct pt_iommu pt_iommu; > + struct pt_iommu_x86_64 pt_iommu_x86_64; > + }; > + struct hv_iommu_dev *hv_iommu; > + struct hv_input_device_domain device_domain; > + u64 pgsize_bitmap; > +}; > + > +struct hv_pci_busdata { > + int pci_domain_nr; > + u32 logical_dev_id_prefix; > + struct list_head list; > +}; > + > +struct hv_iommu_endpoint { > + struct device *dev; > + struct hv_iommu_dev *hv_iommu; > + struct hv_iommu_domain *hv_domain; > +}; > + > +#define to_hv_iommu_domain(d) \ > + container_of(d, struct hv_iommu_domain, domain) > + > +#endif /* _HYPERV_IOMMU_H */ > diff --git a/drivers/pci/controller/pci-hyperv.c > b/drivers/pci/controller/pci-hyperv.c index > cfc8fa403dad..a4af9c8c2220 100644 --- > a/drivers/pci/controller/pci-hyperv.c +++ > b/drivers/pci/controller/pci-hyperv.c @@ -3715,6 +3715,7 @@ static > int hv_pci_probe(struct hv_device *hdev, struct hv_pcibus_device > *hbus; int ret, dom; > u16 dom_req; > + u32 prefix; > char *name; > > bridge = devm_pci_alloc_host_bridge(&hdev->device, 0); > @@ -3857,13 +3858,25 @@ static int hv_pci_probe(struct hv_device > *hdev, > hbus->state = hv_pcibus_probed; > > - ret = create_root_hv_pci_bus(hbus); > + /* Notify pvIOMMU before any device on the bus is scanned. */ > + prefix = (hdev->dev_instance.b[5] << 24) | > + (hdev->dev_instance.b[4] << 16) | > + (hdev->dev_instance.b[7] << 8) | > + (hdev->dev_instance.b[6] & 0xf8); > + > + ret = hv_iommu_register_pci_bus(dom, prefix); > if (ret) > goto free_windows; > > + ret = create_root_hv_pci_bus(hbus); > + if (ret) > + goto unregister_pviommu; > + > mutex_unlock(&hbus->state_lock); > return 0; > > +unregister_pviommu: > + hv_iommu_unregister_pci_bus(dom); > free_windows: > hv_pci_free_bridge_windows(hbus); > exit_d0: > @@ -3974,8 +3987,10 @@ static int hv_pci_bus_exit(struct hv_device > *hdev, bool keep_devs) static void hv_pci_remove(struct hv_device > *hdev) { > struct hv_pcibus_device *hbus; > + int dom; > > hbus = hv_get_drvdata(hdev); > + dom = hbus->bridge->domain_nr; > if (hbus->state == hv_pcibus_installed) { > tasklet_disable(&hdev->channel->callback_event); > hbus->state = hv_pcibus_removing; > @@ -3994,6 +4009,8 @@ static void hv_pci_remove(struct hv_device > *hdev) hv_pci_remove_slots(hbus); > pci_remove_root_bus(hbus->bridge->bus); > pci_unlock_rescan_remove(); > + > + hv_iommu_unregister_pci_bus(dom); > } > > hv_pci_bus_exit(hdev, false); > diff --git a/include/asm-generic/mshyperv.h > b/include/asm-generic/mshyperv.h index bf601d67cecb..b71345c74568 > 100644 --- a/include/asm-generic/mshyperv.h > +++ b/include/asm-generic/mshyperv.h > @@ -73,6 +73,18 @@ extern enum hv_partition_type > hv_curr_partition_type; extern void * __percpu *hyperv_pcpu_input_arg; > extern void * __percpu *hyperv_pcpu_output_arg; > > +#ifdef CONFIG_HYPERV_PVIOMMU > +int hv_iommu_register_pci_bus(int pci_domain_nr, u32 > logical_dev_id_prefix); +void hv_iommu_unregister_pci_bus(int > pci_domain_nr); +#else > +static inline int hv_iommu_register_pci_bus(int pci_domain_nr, > + u32 > logical_dev_id_prefix) +{ > + return 0; > +} > +static inline void hv_iommu_unregister_pci_bus(int pci_domain_nr) { } > +#endif > + > u64 hv_do_hypercall(u64 control, void *inputaddr, void *outputaddr); > u64 hv_do_fast_hypercall8(u16 control, u64 input8); > u64 hv_do_fast_hypercall16(u16 control, u64 input1, u64 input2); ^ permalink raw reply [flat|nested] 6+ messages in thread
* [PATCH v1 4/4] iommu/hyperv: Add page-selective IOTLB flush support 2026-05-11 16:24 [PATCH v1 0/4] Hyper-V: Add para-virtualized IOMMU support for Linux guests Yu Zhang ` (2 preceding siblings ...) 2026-05-11 16:24 ` [PATCH v1 3/4] iommu/hyperv: Add para-virtualized IOMMU support for Hyper-V guest Yu Zhang @ 2026-05-11 16:24 ` Yu Zhang 3 siblings, 0 replies; 6+ messages in thread From: Yu Zhang @ 2026-05-11 16:24 UTC (permalink / raw) To: linux-kernel, linux-hyperv, iommu, linux-pci, linux-arch Cc: wei.liu, kys, haiyangz, decui, longli, joro, will, robin.murphy, bhelgaas, kwilczynski, lpieralisi, mani, robh, arnd, jgg, mhklinux, jacob.pan, tgopinath, easwar.hariharan Add page-selective IOTLB flush using HVCALL_FLUSH_DEVICE_DOMAIN_LIST. This hypercall accepts a list of (page_number, page_mask_shift) entries, enabling finer-grained IOTLB invalidation compared to the domain-wide HVCALL_FLUSH_DEVICE_DOMAIN used by hv_iommu_flush_iotlb_all(). hv_iommu_fill_iova_list() decomposes a contiguous IOVA range into a minimal set of aligned power-of-two regions that fit in a single hypercall input page. When the range exceeds the page capacity, the code falls back to a full domain flush automatically. Signed-off-by: Yu Zhang <zhangyu1@linux.microsoft.com> Signed-off-by: Easwar Hariharan <easwar.hariharan@linux.microsoft.com> --- drivers/iommu/hyperv/iommu.c | 91 +++++++++++++++++++++++++++++++++++- include/hyperv/hvgdk_mini.h | 1 + include/hyperv/hvhdk_mini.h | 17 +++++++ 3 files changed, 108 insertions(+), 1 deletion(-) diff --git a/drivers/iommu/hyperv/iommu.c b/drivers/iommu/hyperv/iommu.c index e5fc625314b5..3bca362b7815 100644 --- a/drivers/iommu/hyperv/iommu.c +++ b/drivers/iommu/hyperv/iommu.c @@ -486,10 +486,98 @@ static void hv_iommu_flush_iotlb_all(struct iommu_domain *domain) hv_flush_device_domain(to_hv_iommu_domain(domain)); } +/* Max number of iova_list entries in a single hypercall input page. */ +#define HV_IOMMU_MAX_FLUSH_VA_COUNT \ + ((HV_HYP_PAGE_SIZE - sizeof(struct hv_input_flush_device_domain_list)) / \ + sizeof(union hv_iommu_flush_va)) + +/* Returned by hv_iommu_fill_iova_list() when the range exceeds the capacity */ +#define HV_IOMMU_FLUSH_VA_OVERFLOW U16_MAX + +static inline u16 hv_iommu_fill_iova_list(union hv_iommu_flush_va *iova_list, + unsigned long start, + unsigned long end) +{ + unsigned long start_pfn = start >> PAGE_SHIFT; + unsigned long end_pfn = PAGE_ALIGN(end) >> PAGE_SHIFT; + unsigned long nr_pages = end_pfn - start_pfn; + u16 count = 0; + + while (nr_pages > 0) { + unsigned long flush_pages; + int order; + unsigned long pfn_align; + unsigned long size_align; + + if (count >= HV_IOMMU_MAX_FLUSH_VA_COUNT) { + count = HV_IOMMU_FLUSH_VA_OVERFLOW; + break; + } + + if (start_pfn) + pfn_align = __ffs(start_pfn); + else + pfn_align = BITS_PER_LONG - 1; + + size_align = __fls(nr_pages); + order = min(pfn_align, size_align); + iova_list[count].page_mask_shift = order; + iova_list[count].page_number = start_pfn; + + flush_pages = 1UL << order; + start_pfn += flush_pages; + nr_pages -= flush_pages; + count++; + } + + return count; +} + +static void hv_flush_device_domain_list(struct hv_iommu_domain *hv_domain, + struct iommu_iotlb_gather *iotlb_gather) +{ + u64 status; + u16 count; + unsigned long flags; + struct hv_input_flush_device_domain_list *input; + + local_irq_save(flags); + + input = *this_cpu_ptr(hyperv_pcpu_input_arg); + memset(input, 0, sizeof(*input)); + + input->device_domain = hv_domain->device_domain; + input->flags |= HV_FLUSH_DEVICE_DOMAIN_LIST_IOMMU_FORMAT; + count = hv_iommu_fill_iova_list(input->iova_list, + iotlb_gather->start, + iotlb_gather->end); + if (count == HV_IOMMU_FLUSH_VA_OVERFLOW) { + /* + * Range exceeds hypercall page capacity. Fall back to a full + * domain flush. + */ + struct hv_input_flush_device_domain *flush_all = (void *)input; + + memset(flush_all, 0, sizeof(*flush_all)); + flush_all->device_domain = hv_domain->device_domain; + status = hv_do_hypercall(HVCALL_FLUSH_DEVICE_DOMAIN, + flush_all, NULL); + } else { + status = hv_do_rep_hypercall( + HVCALL_FLUSH_DEVICE_DOMAIN_LIST, + count, 0, input, NULL); + } + + local_irq_restore(flags); + + if (!hv_result_success(status)) + pr_err("HVCALL_FLUSH_DEVICE_DOMAIN_LIST failed, status %lld\n", status); +} + static void hv_iommu_iotlb_sync(struct iommu_domain *domain, struct iommu_iotlb_gather *iotlb_gather) { - hv_flush_device_domain(to_hv_iommu_domain(domain)); + hv_flush_device_domain_list(to_hv_iommu_domain(domain), iotlb_gather); iommu_put_pages_list(&iotlb_gather->freelist); } @@ -543,6 +631,7 @@ static struct iommu_domain *hv_iommu_domain_alloc_paging(struct device *dev) cfg.common.hw_max_vasz_lg2 = hv_iommu_device->max_iova_width; cfg.common.hw_max_oasz_lg2 = 52; + cfg.common.features |= BIT(PT_FEAT_FLUSH_RANGE); cfg.top_level = (hv_iommu_device->max_iova_width > 48) ? 4 : 3; ret = pt_iommu_x86_64_init(&hv_domain->pt_iommu_x86_64, &cfg, GFP_KERNEL); diff --git a/include/hyperv/hvgdk_mini.h b/include/hyperv/hvgdk_mini.h index 5bdbb44da112..eaaf87171478 100644 --- a/include/hyperv/hvgdk_mini.h +++ b/include/hyperv/hvgdk_mini.h @@ -496,6 +496,7 @@ union hv_vp_assist_msr_contents { /* HV_REGISTER_VP_ASSIST_PAGE */ #define HVCALL_GET_GPA_PAGES_ACCESS_STATES 0x00c9 #define HVCALL_CONFIGURE_DEVICE_DOMAIN 0x00ce #define HVCALL_FLUSH_DEVICE_DOMAIN 0x00d0 +#define HVCALL_FLUSH_DEVICE_DOMAIN_LIST 0x00d1 #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 diff --git a/include/hyperv/hvhdk_mini.h b/include/hyperv/hvhdk_mini.h index 493608e791b4..f51d5d9467f1 100644 --- a/include/hyperv/hvhdk_mini.h +++ b/include/hyperv/hvhdk_mini.h @@ -671,4 +671,21 @@ struct hv_input_flush_device_domain { u32 reserved; } __packed; +union hv_iommu_flush_va { + u64 iova; + struct { + u64 page_mask_shift : 12; + u64 page_number : 52; + }; +} __packed; + + +struct hv_input_flush_device_domain_list { + struct hv_input_device_domain device_domain; +#define HV_FLUSH_DEVICE_DOMAIN_LIST_IOMMU_FORMAT (1 << 0) + u32 flags; + u32 reserved; + union hv_iommu_flush_va iova_list[]; +} __packed; + #endif /* _HV_HVHDK_MINI_H */ -- 2.52.0 ^ permalink raw reply related [flat|nested] 6+ messages in thread
end of thread, other threads:[~2026-05-13 18:39 UTC | newest] Thread overview: 6+ messages (download: mbox.gz follow: Atom feed -- links below jump to the message on this page -- 2026-05-11 16:24 [PATCH v1 0/4] Hyper-V: Add para-virtualized IOMMU support for Linux guests Yu Zhang 2026-05-11 16:24 ` [PATCH v1 1/4] iommu: Move Hyper-V IOMMU driver to its own subdirectory Yu Zhang 2026-05-11 16:24 ` [PATCH v1 2/4] hyperv: Introduce new hypercall interfaces used by Hyper-V guest IOMMU Yu Zhang 2026-05-11 16:24 ` [PATCH v1 3/4] iommu/hyperv: Add para-virtualized IOMMU support for Hyper-V guest Yu Zhang 2026-05-13 18:39 ` Jacob Pan 2026-05-11 16:24 ` [PATCH v1 4/4] iommu/hyperv: Add page-selective IOTLB flush support Yu Zhang
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