This patch set allows the Hyper-V code to boot on ARM64 inside a Virtual Trust Level. These levels are a part of the Virtual Secure Mode documented in the Top-Level Functional Specification available at https://learn.microsoft.com/en-us/virtualization/hyper-v-on-windows/tlfs/vsm. The OpenHCL paravisor https://github.com/microsoft/openvmm/tree/main/openhcl can serve as a practical application of these patches on ARM64. For validation, I built kernels for the {x86_64, ARM64} x {VTL0, VTL2} set with a small initrd embedded into the kernel and booted VMs managed by Hyper-V and OpenVMM off of that. Starting from V5, the patch series includes a non-functional change to KVM on arm64 which I tested as well. [V5] - Provide and use a common SMCCC-based infra for the arm64 hypervisor guests to detect hypervisor presence. ** Thank you, Arnd! ** - Fix line wraps to follow the rest of the code. - Open-code getting IRQ domain parent in the ACPI case to make the code better. ** Thank you, Bjorn! ** - Test the binding with the latest dtschema. - Clean up the commit title and description. - Use proper defines for known constants. ** Thank you, Krzysztof! ** - Extend comment on why ACPI v6 is checked for. - Reorder patches to make sure that even with partial series application the compilation succeeds. - Report VTL the kernel runs in. - Use "X86_64" in Kconfig rather than "X86". - Extract a non-functional change for hv_get_vmbus_root_device() into a separate patch. ** Thank you, Michael! ** [V4] https://lore.kernel.org/linux-hyperv/20250212014321.1108840-1-romank@xxxxxxxxxxxxxxxxxxx/ - Fixed wording to match acronyms defined in the "Terms and Abbreviations" section of the SMCCC specification throughout the patch series. **Thank you, Michael!** - Replaced the hypervisor ID containing ASCII with an UUID as required by the specification. **Thank you, Michael!** - Added an explicit check for `SMCCC_RET_NOT_SUPPORTED` when discovering the hypervisor presence to make the backward compatibility obvious. **Thank you, Saurabh!** - Split the fix for `get_vtl(void)` out to make it easier to backport. - Refactored the configuration options as requested to eliminate the risk of building non-functional kernels with randomly selected options. **Thank you, Michael!** - Refactored the changes not to introduce an additional file with a one-line function. **Thank you, Wei!** - Fixed change description for the VMBus DeviceTree changes, used `scripts/get_maintainers.pl` on the latest kernel to get the up-to-date list of maintainers as requested. **Thank you, Krzysztof!** - Removed the added (paranoidal+superfluous) checks for DMA coherence in the VMBus driver and instead relied on the DMA and the OF subsystem code. **Thank you, Arnd, Krzysztof, Michael!** - Used another set of APIs for discovering the hardware interrupt number in the VMBus driver to be able to build the driver as a module. **Thank you, Michael, Saurabh!** - Renamed the newly introduced `get_vmbus_root_device(void)` function to `hv_get_vmbus_root_device(void)` as requested. **Thank you, Wei!** - Applied the suggested small-scale refactoring to simplify changes to the Hyper-V PCI driver. Taking the offered liberty of doing the large scale refactoring in another patch series. **Thank you, Michael!** - Added a fix for the issue discovered internally where the CPU would not get the interrupt from a PCI device attached to VTL2 as the shared peripheral interrupt number (SPI) was not offset by 32 (the first valid SPI number). **Thank you, Brian!** [V3] https://lore.kernel.org/lkml/20240726225910.1912537-1-romank@xxxxxxxxxxxxxxxxxxx/ - Employed the SMCCC function recently implemented in the Microsoft Hyper-V hypervisor to detect running on Hyper-V/arm64. No dependence on ACPI/DT is needed anymore although the source code still falls back to ACPI as the new hypervisor might be available only in the Windows Insiders channel just yet. - As a part of the above, refactored detecting the hypervisor via ACPI FADT. - There was a suggestion to explore whether it is feasible or not to express that ACPI must be absent for the VTL mode and present for the regular guests in the Hyper-V Kconfig file. My current conclusion is that this will require refactoring in many places. That becomes especially convoluted on x86_64 due to the MSI and APIC dependencies. I'd ask to let us tackle that in another patch series (or chalk up to nice-have's rather than fires to put out) to separate concerns and decrease chances of breakage. - While refactoring `get_vtl(void)` and the related code, fixed the hypercall output address not to overlap with the input as the Hyper-V TLFS mandates: "The input and output parameter lists cannot overlap or cross page boundaries." See https://learn.microsoft.com/en-us/virtualization/hyper-v-on-windows/tlfs/hypercall-interface for more. Some might argue that should've been a topic for a separate patch series; I'd counter that the change is well-contained (one line), has no dependencies, and makes the code legal. - Made the VTL boot code (c)leaner as was suggested. - Set DMA cache coherency for the VMBus. - Updated DT bindings in the VMBus documentation (separated out into a new patch). - Fixed `vmbus_set_irq` to use the API that works both for the ACPI and OF. - Reworked setting up the vPCI MSI IRQ domain in the non-ACPI case. The logic looks a bit fiddly/ad-hoc as I couldn't find the API that would fit the bill. Added comments to explain myself. [V2] https://lore.kernel.org/all/20240514224508.212318-1-romank@xxxxxxxxxxxxxxxxxxx/ - Decreased number of #ifdef's - Updated the wording in the commit messages to adhere to the guidlines - Sending to the correct set of maintainers and mail lists [V1] https://lore.kernel.org/all/20240510160602.1311352-1-romank@xxxxxxxxxxxxxxxxxxx/ Roman Kisel (11): arm64: kvm, smccc: Introduce and use API for detectting hypervisor presence arm64: hyperv: Use SMCCC to detect hypervisor presence Drivers: hv: Enable VTL mode for arm64 Drivers: hv: Provide arch-neutral implementation of get_vtl() arm64: hyperv: Initialize the Virtual Trust Level field arm64, x86: hyperv: Report the VTL the system boots in dt-bindings: microsoft,vmbus: Add interrupts and DMA coherence Drivers: hv: vmbus: Get the IRQ number from DeviceTree Drivers: hv: vmbus: Introduce hv_get_vmbus_root_device() ACPI: irq: Introduce acpi_get_gsi_dispatcher() PCI: hv: Get vPCI MSI IRQ domain from DeviceTree .../bindings/bus/microsoft,vmbus.yaml | 8 +- arch/arm64/hyperv/mshyperv.c | 46 +++++++++-- arch/arm64/kvm/hypercalls.c | 5 +- arch/x86/hyperv/hv_init.c | 34 -------- arch/x86/hyperv/hv_vtl.c | 2 +- drivers/acpi/irq.c | 14 +++- drivers/firmware/smccc/kvm_guest.c | 10 +-- drivers/firmware/smccc/smccc.c | 19 +++++ drivers/hv/Kconfig | 10 ++- drivers/hv/hv_common.c | 31 ++++++++ drivers/hv/vmbus_drv.c | 59 ++++++++++++-- drivers/pci/controller/pci-hyperv.c | 79 +++++++++++++++++-- include/asm-generic/mshyperv.h | 6 ++ include/hyperv/hvgdk_mini.h | 2 +- include/linux/acpi.h | 5 +- include/linux/arm-smccc.h | 55 ++++++++++++- include/linux/hyperv.h | 2 + 17 files changed, 308 insertions(+), 79 deletions(-) base-commit: 3a7f7785eae7cf012af128ca9e383c91e4955354 -- 2.43.0
