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. [V4] - 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 (6): arm64: hyperv: Use SMCCC to detect hypervisor presence Drivers: hv: Enable VTL mode for arm64 Drivers: hv: Provide arch-neutral implementation of get_vtl() dt-bindings: microsoft,vmbus: Add GIC and DMA coherence to the example Drivers: hv: vmbus: Get the IRQ number from DeviceTree PCI: hv: Get vPCI MSI IRQ domain from DeviceTree .../bindings/bus/microsoft,vmbus.yaml | 11 +++ arch/arm64/hyperv/mshyperv.c | 43 ++++++++++-- arch/arm64/include/asm/mshyperv.h | 5 ++ arch/x86/hyperv/hv_init.c | 34 --------- drivers/hv/Kconfig | 10 +-- drivers/hv/hv_common.c | 32 +++++++++ drivers/hv/vmbus_drv.c | 59 +++++++++++++--- drivers/pci/controller/pci-hyperv.c | 69 +++++++++++++++++-- include/asm-generic/mshyperv.h | 6 ++ include/hyperv/hvgdk_mini.h | 2 +- include/linux/hyperv.h | 2 + 11 files changed, 215 insertions(+), 58 deletions(-) base-commit: 2e03358be78b65d28b66e17aca9e0c8700b0df78 -- 2.43.0
