Hi Mukesh, On Mon, 6 Jul 2026 17:08:50 -0700 Mukesh R <[email protected]> wrote:
> From: Mukesh R <[email protected]> > To: Yu Zhang <[email protected]>, > [email protected], [email protected], > [email protected], [email protected], > [email protected] Cc: [email protected], [email protected], > [email protected], [email protected], [email protected], > [email protected], [email protected], [email protected], > [email protected], [email protected], [email protected], > [email protected], [email protected], [email protected], [email protected], > [email protected], [email protected], > [email protected], [email protected] > Subject: Re: [PATCH v2 3/4] iommu/hyperv: Add para-virtualized IOMMU > support for Hyper-V guest Date: Mon, 6 Jul 2026 17:08:50 -0700 > User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 > Thunderbird/91.13.1 > > On 7/2/26 09:05, Yu Zhang 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. > > > > To identify a device in its hypercall interface, the driver looks > > up the logical device ID prefix registered for the device's PCI > > domain (see the logical device ID registry in hv_common.c) and > > combines it with the PCI function number of the endpoint device. > > > > Co-developed-by: Wei Liu <[email protected]> > > Signed-off-by: Wei Liu <[email protected]> > > Co-developed-by: Easwar Hariharan > > <[email protected]> Signed-off-by: Easwar > > Hariharan <[email protected]> Signed-off-by: Yu > > Zhang <[email protected]> --- > > arch/x86/hyperv/hv_init.c | 4 + > > arch/x86/include/asm/mshyperv.h | 4 + > > drivers/iommu/Kconfig | 1 + > > drivers/iommu/hyperv/Kconfig | 16 + > > drivers/iommu/hyperv/Makefile | 1 + > > drivers/iommu/hyperv/iommu.c | 620 > > ++++++++++++++++++++++++++++++++ drivers/iommu/hyperv/iommu.h | > > 51 +++ 7 files changed, 697 insertions(+) > > create mode 100644 drivers/iommu/hyperv/Kconfig > > create mode 100644 drivers/iommu/hyperv/iommu.c > > Hey Jacob, > > You had suggested I rename iommu.c to iommu-root.c (I called it > hv-iommu-root.c eventually), so this needs to be renamed also, > right? yes, I agree. I feel it is clearer to name it hv-iommu-guest.c since this is a guest only driver.
