[PATCH v0 00/15] PCI passthru on Hyper-V (Part I)

Mukesh R
2026-01-20T06:43:28Z

From: Mukesh Rathor <mrathor@linux.microsoft.com>

Implement passthru of PCI devices to unprivileged virtual machines
(VMs) when Linux is running as a privileged VM on Microsoft Hyper-V
hypervisor. This support is made to fit within the workings of VFIO
framework, and any VMM needing to use it must use the VFIO subsystem.
This supports both full device passthru and SR-IOV based VFs.

There are 3 cases where Linux can run as a privileged VM (aka MSHV):
Baremetal root (meaning Hyper-V+Linux), L1VH, and Nested.

At a high level, the hypervisor supports traditional mapped iommu domains
that use explicit map and unmap hypercalls for mapping and unmapping guest
RAM into the iommu subsystem. Hyper-V also has a concept of direct attach
devices whereby the iommu subsystem simply uses the guest HW page table
(ept/npt/..). This series adds support for both, and both are made to
work in VFIO type1 subsystem.

While this Part I focuses on memory mappings, upcoming Part II
will focus on irq bypass along with some minor irq remapping
updates.

This patch series was tested using Cloud Hypervisor verion 48. Qemu
support of MSHV is in the works, and that will be extended to include
PCI passthru and SR-IOV support also in near future.

Based on: 8f0b4cce4481 (origin/hyperv-next)

Thanks,
-Mukesh

Mukesh Rathor (15):
iommu/hyperv: rename hyperv-iommu.c to hyperv-irq.c
x86/hyperv: cosmetic changes in irqdomain.c for readability
x86/hyperv: add insufficient memory support in irqdomain.c
mshv: Provide a way to get partition id if running in a VMM process
mshv: Declarations and definitions for VFIO-MSHV bridge device
mshv: Implement mshv bridge device for VFIO
mshv: Add ioctl support for MSHV-VFIO bridge device
PCI: hv: rename hv_compose_msi_msg to hv_vmbus_compose_msi_msg
mshv: Import data structs around device domains and irq remapping
PCI: hv: Build device id for a VMBus device
x86/hyperv: Build logical device ids for PCI passthru hcalls
x86/hyperv: Implement hyperv virtual iommu
x86/hyperv: Basic interrupt support for direct attached devices
mshv: Remove mapping of mmio space during map user ioctl
mshv: Populate mmio mappings for PCI passthru

MAINTAINERS | 1 +
arch/arm64/include/asm/mshyperv.h | 15 +
arch/x86/hyperv/irqdomain.c | 314 ++++++---
arch/x86/include/asm/mshyperv.h | 21 +
arch/x86/kernel/pci-dma.c | 2 +
drivers/hv/Makefile | 3 +-
drivers/hv/mshv_root.h | 24 +
drivers/hv/mshv_root_main.c | 296 +++++++-
drivers/hv/mshv_vfio.c | 210 ++++++
drivers/iommu/Kconfig | 1 +
drivers/iommu/Makefile | 2 +-
drivers/iommu/hyperv-iommu.c | 1004 +++++++++++++++++++++------
drivers/iommu/hyperv-irq.c | 330 +++++++++
drivers/pci/controller/pci-hyperv.c | 207 ++++--
include/asm-generic/mshyperv.h | 1 +
include/hyperv/hvgdk_mini.h | 11 +
include/hyperv/hvhdk_mini.h | 112 +++
include/linux/hyperv.h | 6 +
include/uapi/linux/mshv.h | 31 +
19 files changed, 2182 insertions(+), 409 deletions(-)
create mode 100644 drivers/hv/mshv_vfio.c
create mode 100644 drivers/iommu/hyperv-irq.c

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