Hi Mukesh, On Mon, 19 Jan 2026 22:42:15 -0800 Mukesh R <[email protected]> wrote:
> From: Mukesh Rathor <[email protected]> > > 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. > I think some introduction/background to L1VH would help. > 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. It may be clearer to state that the hypervisor supports Linux IOMMU paging domains through map/unmap hypercalls, mapping GPAs to HPAs using stage‑2 I/O page tables. > 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. > This may warrant introducing a new IOMMU domain feature flag, as it performs mappings but does not support map/unmap semantics in the same way as a paging domain. > 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 >
