On Mon, Sep 07, 2026 at 04:48:23PM +0800, Yu Zhang wrote: Hi Joerg, Jason,
A gentle ping on this series. Could you let me know whether it is ready to be picked up, or whether any further changes or acks are needed? Thanks a lot! B.R. Yu > > Hi Jason, Joerg, > > > Do you have any further comments on this version, particularly > any remaining issues that would warrant a respin before the series > can be considered for inclusion? Thanks a lot! > > B.R. > Yu > > > 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 and attachment > > 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 standard x86 MSI interrupt range > > (0xfee00000 - 0xfeefffff) is reserved from normal IOVA mappings. > > 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. > > > > * Guest Hibernation > > Guest hibernation and resume are not supported by this initial > > implementation. The current pvIOMMU interface does not define how > > Hyper-V device-domain objects and device attachments are restored. > > > > Testing: > > Validated with the following configurations: > > - NVMe devices assigned to the guest on AMD platforms, tested > > with fio. > > - Intel DSA devices assigned to the guest, tested with dmatest. > > - dma_map_benchmark for DMA mapping performance evaluation. > > > > Changelog: > > > > v4[1] -> v5: > > - Added Michael Kelley's Reviewed-by tags for patch 1/2/3/4. > > > > - hv: logical device ID registry: > > - Used four-digit hexadecimal values to print PCI domain numbers. > > - Included the PCI domain number in the unregister failure warning. > > > > - iommu/hyperv: para-virtualized IOMMU: > > - Removed the unused per-device endpoint structure, allocation, > > private pointer, and release_device() callback. > > - Clarified the logical device ID lookup failure message. > > - Read the ATS capability from the IOMMU associated with the domain > > instead of the global IOMMU pointer. > > > > - iommu/hyperv: page-selective IOTLB flush: > > - Unified normal and full-range descriptor construction around the > > aligned range start. > > - Used max() to express the minimum Hyper-V page granularity. > > - Reported Hyper-V status values in warnings when the flush fails. > > > > v3[2] -> v4: > > - Added Jacob Pan's Reviewed-by tag for patch 1/4/5. > > > > - hyperv: hypercall interfaces: > > - Added the authoritative Hyper-V type names to imported definitions. > > - Added HV_STATUS_DEVICE_ALREADY_IN_DOMAIN and mapped it to -EEXIST. > > > > - hv: logical device ID registry: > > - Made the registry independent of CONFIG_HYPERV_PVIOMMU. > > - Renamed the APIs to hv_pci_xxx_dev_id(), > > - Reworked initialization and error cleanup to propagate failures. > > - Return -EEXIST with a warning for duplicate registration. > > > > - iommu/x86: architectural MSI reserved region: > > - Replaced the exported range constants with > > iommu_alloc_resv_x86_msi_region(). > > > > - iommu/hyperv: para-virtualized IOMMU: > > - Accepted HV_STATUS_DEVICE_ALREADY_IN_DOMAIN as a successful attach, > > and removed the blocking-domain-specific duplicate check. > > - Removed the redundant ATS disable from release_device(); ATS is > > disabled when attaching the release domain. > > > > - iommu/hyperv: page-selective IOTLB flush: > > - Removed the redundant include of linux/hyperv.h. > > - Documented that the list flush also invalidates non-leaf page-walk > > caches before detached page-table pages are freed. > > > > v2[3] -> v3: > > - Added a separate patch defining the common x86 architectural MSI > > reserved range and converted the Intel, AMD, and Hyper-V IOMMU > > drivers to use it. > > > > - hyperv: hypercall interfaces: > > - Used BIT_ULL() for 64-bit capability flags. > > - Matched the create-device-domain input layout to the 32-byte > > Hyper-V ABI. > > - Corrected the page-selective flush range layout to 6/6/52 bits. > > > > - hv: logical device ID registry: > > - Replaced the linear list with an rhashtable for the sparse PCI > > domain number mapping. > > - Used RCU-protected lookup and deferred freeing on removal. > > - Simplified the registration and cleanup paths. > > > > - iommu/hyperv: para-virtualized IOMMU: > > - Renamed the guest driver source to hv-iommu-guest.c. > > - Enabled ATS only after a device-domain attachment succeeds, and > > disabled ATS before attaching the blocking domain. > > - Removed the obsolete deferred-flush capability, unused geometry, > > and redundant device-private-data clearing. > > - Made the Hyper-V domain settings explicit at each caller instead > > of deriving them from the Linux domain type. > > - Added transactional create/configure domain handling with rollback. > > - Required only the base page size and masked the domain page-size > > bitmap with the Hyper-V-supported bitmap. > > - Silenced detection for unsupported hosts while retaining errors > > for actual hypercall and capability failures. > > - Clarified Kconfig support for assigned PCI devices and documented > > the lack of guest hibernation/resume support. > > > > - iommu/hyperv: page-selective IOTLB flush: > > - Removed the inclusive-end overflow and kept the range calculation > > in byte addresses until the final page conversion. > > - Cleared both the fixed hypercall header and the range entry. > > - Warned on selective-flush failure before falling back to a > > full-domain flush. > > > > v1[4] -> v2: > > - Dropped the "move to subdirectory" patch; the directory now exists > > upstream. > > > > - hv: logical device ID registry: > > - Moved the registry to hv_common.c so it can be shared, and derived > > the prefix via a shared helper instead of caching it in pci-hyperv's > > private struct. > > - Moved the lookup out of the irq-disabled region (PREEMPT_RT). > > > > - iommu/hyperv: para-virtualized IOMMU: > > - Removed the unused detach_dev op. > > - Rejected a hypervisor not advertising x86 page sizes instead of > > masking and warning. > > - Statically initialized the identity and blocking domains. > > - Gave the blocking domain its own attach op, which returns the hypercall > > status and WARNs on failure. > > > > - iommu/hyperv: page-selective IOTLB flush: > > - Used a single descriptor covering a slightly larger power-of-two > > range, instead of splitting the range into multiple descriptors. > > - Fixed the inclusive-end corner case in the flush range calculation. > > > > RFC v1[5] -> v1[4]: > > - 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 > > - 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] v4: > > https://lore.kernel.org/linux-hyperv/[email protected]/ > > [2] v3: > > https://lore.kernel.org/linux-hyperv/[email protected]/ > > [3] v2: > > https://lore.kernel.org/linux-hyperv/[email protected]/ > > [4] v1: > > https://lore.kernel.org/linux-hyperv/[email protected]/ > > [5] RFC v1: > > https://lore.kernel.org/linux-hyperv/[email protected]/ > > > > Wei Liu (1): > > hyperv: Introduce new hypercall interfaces used by Hyper-V guest IOMMU > > > > Yu Zhang (4): > > Drivers: hv: Add logical device ID registry for vPCI devices > > iommu/x86: Add architectural MSI reserved region helper > > iommu/hyperv: Add para-virtualized IOMMU support for Hyper-V guest > > iommu/hyperv: Add page-selective IOTLB flush support > > > > arch/x86/hyperv/hv_init.c | 4 + > > arch/x86/include/asm/iommu.h | 14 + > > arch/x86/include/asm/mshyperv.h | 4 + > > drivers/hv/hv_common.c | 115 +++++ > > drivers/iommu/Kconfig | 1 + > > drivers/iommu/amd/iommu.c | 6 +- > > drivers/iommu/hyperv/Kconfig | 16 + > > drivers/iommu/hyperv/Makefile | 1 + > > drivers/iommu/hyperv/hv-iommu-guest.c | 679 ++++++++++++++++++++++++++ > > drivers/iommu/hyperv/iommu.h | 44 ++ > > drivers/iommu/intel/iommu.c | 6 +- > > drivers/pci/controller/pci-hyperv.c | 21 +- > > include/asm-generic/mshyperv.h | 4 + > > include/hyperv/hvgdk_mini.h | 10 + > > include/hyperv/hvhdk_mini.h | 155 ++++++ > > include/linux/hyperv.h | 8 + > > 16 files changed, 1073 insertions(+), 15 deletions(-) > > create mode 100644 drivers/iommu/hyperv/Kconfig > > create mode 100644 drivers/iommu/hyperv/hv-iommu-guest.c > > create mode 100644 drivers/iommu/hyperv/iommu.h > > > > -- > > 2.52.0 > > >
