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2025-05-23arm64, x86: hyperv: Report the VTL the system boots inRoman Kisel
The hyperv guest code might run in various Virtual Trust Levels. Report the level when the kernel boots in the non-default (0) one. Signed-off-by: Roman Kisel <romank@linux.microsoft.com> Reviewed-by: Michael Kelley <mhklinux@outlook.com> Link: https://lore.kernel.org/r/20250428210742.435282-7-romank@linux.microsoft.com Signed-off-by: Wei Liu <wei.liu@kernel.org> Message-ID: <20250428210742.435282-7-romank@linux.microsoft.com>
2025-05-23arm64: hyperv: Initialize the Virtual Trust Level fieldRoman Kisel
Various parts of the hyperv code need to know what VTL the kernel runs at, most notably VMBus needs that to establish communication with the host. Initialize the Virtual Trust Level field to enable booting in the Virtual Trust Level. Signed-off-by: Roman Kisel <romank@linux.microsoft.com> Reviewed-by: Michael Kelley <mhklinux@outlook.com> Link: https://lore.kernel.org/r/20250428210742.435282-6-romank@linux.microsoft.com Signed-off-by: Wei Liu <wei.liu@kernel.org> Message-ID: <20250428210742.435282-6-romank@linux.microsoft.com>
2025-05-23arm64: hyperv: Use SMCCC to detect hypervisor presenceRoman Kisel
The arm64 Hyper-V startup path relies on ACPI to detect running under a Hyper-V compatible hypervisor. That doesn't work on non-ACPI systems. Hoist the ACPI detection logic into a separate function. Then use the vendor-specific hypervisor service call (implemented recently in Hyper-V) via SMCCC in the non-ACPI case. Signed-off-by: Roman Kisel <romank@linux.microsoft.com> Reviewed-by: Michael Kelley <mhklinux@outlook.com> Link: https://lore.kernel.org/r/20250428210742.435282-3-romank@linux.microsoft.com Signed-off-by: Wei Liu <wei.liu@kernel.org> Message-ID: <20250428210742.435282-3-romank@linux.microsoft.com>
2025-03-20Drivers: hv: Export some functions for use by root partition moduleNuno Das Neves
hv_get_hypervisor_version(), hv_call_deposit_pages(), and hv_call_create_vp(), are all needed in-module with CONFIG_MSHV_ROOT=m. Signed-off-by: Nuno Das Neves <nunodasneves@linux.microsoft.com> Reviewed-by: Stanislav Kinsburskii <skinsburskii@microsoft.linux.com> Reviewed-by: Roman Kisel <romank@linux.microsoft.com> Reviewed-by: Easwar Hariharan <eahariha@linux.microsoft.com> Reviewed-by: Tianyu Lan <tiala@microsoft.com> Link: https://lore.kernel.org/r/1741980536-3865-7-git-send-email-nunodasneves@linux.microsoft.com Signed-off-by: Wei Liu <wei.liu@kernel.org> Message-ID: <1741980536-3865-7-git-send-email-nunodasneves@linux.microsoft.com>
2025-03-20arm64/hyperv: Add some missing functions to arm64Nuno Das Neves
These non-nested msr and fast hypercall functions are present in x86, but they must be available in both architectures for the root partition driver code. While at it, remove the redundant 'extern' keywords from the hv_do_hypercall() variants in asm-generic/mshyperv.h. Signed-off-by: Nuno Das Neves <nunodasneves@linux.microsoft.com> Reviewed-by: Stanislav Kinsburskii <skinsburskii@linux.microsoft.com> Reviewed-by: Roman Kisel <romank@linux.microsoft.com> Link: https://lore.kernel.org/r/1741980536-3865-4-git-send-email-nunodasneves@linux.microsoft.com Signed-off-by: Wei Liu <wei.liu@kernel.org> Message-ID: <1741980536-3865-4-git-send-email-nunodasneves@linux.microsoft.com>
2025-02-22hyperv: Change hv_root_partition into a functionNuno Das Neves
Introduce hv_curr_partition_type to store the partition type as an enum. Right now this is limited to guest or root partition, but there will be other kinds in future and the enum is easily extensible. Set up hv_curr_partition_type early in Hyper-V initialization with hv_identify_partition_type(). hv_root_partition() just queries this value, and shouldn't be called before that. Making this check into a function sets the stage for adding a config option to gate the compilation of root partition code. In particular, hv_root_partition() can be stubbed out always be false if root partition support isn't desired. Signed-off-by: Nuno Das Neves <nunodasneves@linux.microsoft.com> Reviewed-by: Easwar Hariharan <eahariha@linux.microsoft.com> Reviewed-by: Michael Kelley <mhklinux@outlook.com> Link: https://lore.kernel.org/r/1740167795-13296-3-git-send-email-nunodasneves@linux.microsoft.com Signed-off-by: Wei Liu <wei.liu@kernel.org> Message-ID: <1740167795-13296-3-git-send-email-nunodasneves@linux.microsoft.com>
2025-02-13hyperv: Move hv_current_partition_id to arch-generic codeNuno Das Neves
Move hv_current_partition_id and hv_get_partition_id() to hv_common.c, and call hv_get_partition_id() on arm64 in hyperv_init(). These aren't specific to x86_64 and will be needed by common code. Set hv_current_partition_id to HV_PARTITION_ID_SELF by default. Rename struct hv_get_partition_id to hv_output_get_partition_id, to make it distinct from the function hv_get_partition_id(), and match the original Hyper-V struct name. Remove the BUG()s. Failing to get the id need not crash the machine. Signed-off-by: Nuno Das Neves <nunodasneves@linux.microsoft.com> Reviewed-by: Michael Kelley <mhklinux@outlook.com> Link: https://lore.kernel.org/r/1738955002-20821-2-git-send-email-nunodasneves@linux.microsoft.com Signed-off-by: Wei Liu <wei.liu@kernel.org> Message-ID: <1738955002-20821-2-git-send-email-nunodasneves@linux.microsoft.com>
2025-01-10hyperv: Switch from hyperv-tlfs.h to hyperv/hvhdk.hNuno Das Neves
Switch to using hvhdk.h everywhere in the kernel. This header includes all the new Hyper-V headers in include/hyperv, which form a superset of the definitions found in hyperv-tlfs.h. This makes it easier to add new Hyper-V interfaces without being restricted to those in the TLFS doc (reflected in hyperv-tlfs.h). To be more consistent with the original Hyper-V code, the names of some definitions are changed slightly. Update those where needed. Update comments in mshyperv.h files to point to include/hyperv for adding new definitions. Signed-off-by: Nuno Das Neves <nunodasneves@linux.microsoft.com> Reviewed-by: Michael Kelley <mhklinux@outlook.com> Reviewed-by: Easwar Hariharan <eahariha@linux.microsoft.com> Signed-off-by: Roman Kisel <romank@linux.microsoft.com> Reviewed-by: Easwar Hariharan <eahariha@linux.microsoft.com> Link: https://lore.kernel.org/r/1732577084-2122-5-git-send-email-nunodasneves@linux.microsoft.com Link: https://lore.kernel.org/r/20250108222138.1623703-3-romank@linux.microsoft.com Signed-off-by: Wei Liu <wei.liu@kernel.org>
2025-01-08hyperv: Clean up unnecessary #includesNuno Das Neves
Remove includes of linux/hyperv.h, mshyperv.h, and hyperv-tlfs.h where they are not used. Signed-off-by: Nuno Das Neves <nunodasneves@linux.microsoft.com> Acked-by: Wei Liu <wei.liu@kernel.org> Reviewed-by: Michael Kelley <mhklinux@outlook.com> Reviewed-by: Easwar Hariharan <eahariha@linux.microsoft.com> Link: https://lore.kernel.org/r/1732577084-2122-3-git-send-email-nunodasneves@linux.microsoft.com Signed-off-by: Wei Liu <wei.liu@kernel.org> Message-ID: <1732577084-2122-3-git-send-email-nunodasneves@linux.microsoft.com>
2024-03-18x86/hyperv: Use Hyper-V entropy to seed guest random number generatorMichael Kelley
A Hyper-V host provides its guest VMs with entropy in a custom ACPI table named "OEM0". The entropy bits are updated each time Hyper-V boots the VM, and are suitable for seeding the Linux guest random number generator (rng). See a brief description of OEM0 in [1]. Generation 2 VMs on Hyper-V use UEFI to boot. Existing EFI code in Linux seeds the rng with entropy bits from the EFI_RNG_PROTOCOL. Via this path, the rng is seeded very early during boot with good entropy. The ACPI OEM0 table provided in such VMs is an additional source of entropy. Generation 1 VMs on Hyper-V boot from BIOS. For these VMs, Linux doesn't currently get any entropy from the Hyper-V host. While this is not fundamentally broken because Linux can generate its own entropy, using the Hyper-V host provided entropy would get the rng off to a better start and would do so earlier in the boot process. Improve the rng seeding for Generation 1 VMs by having Hyper-V specific code in Linux take advantage of the OEM0 table to seed the rng. For Generation 2 VMs, use the OEM0 table to provide additional entropy beyond the EFI_RNG_PROTOCOL. Because the OEM0 table is custom to Hyper-V, parse it directly in the Hyper-V code in the Linux kernel and use add_bootloader_randomness() to add it to the rng. Once the entropy bits are read from OEM0, zero them out in the table so they don't appear in /sys/firmware/acpi/tables/OEM0 in the running VM. The zero'ing is done out of an abundance of caution to avoid potential security risks to the rng. Also set the OEM0 data length to zero so a kexec or other subsequent use of the table won't try to use the zero'ed bits. [1] https://download.microsoft.com/download/1/c/9/1c9813b8-089c-4fef-b2ad-ad80e79403ba/Whitepaper%20-%20The%20Windows%2010%20random%20number%20generation%20infrastructure.pdf Signed-off-by: Michael Kelley <mhklinux@outlook.com> Reviewed-by: Jason A. Donenfeld <Jason@zx2c4.com> Link: https://lore.kernel.org/r/20240318155408.216851-1-mhklinux@outlook.com Signed-off-by: Wei Liu <wei.liu@kernel.org> Message-ID: <20240318155408.216851-1-mhklinux@outlook.com>
2024-03-18hyperv-tlfs: Rename some HV_REGISTER_* defines for consistencyNuno Das Neves
Rename HV_REGISTER_GUEST_OSID to HV_REGISTER_GUEST_OS_ID. This matches the existing HV_X64_MSR_GUEST_OS_ID. Rename HV_REGISTER_CRASH_* to HV_REGISTER_GUEST_CRASH_*. Including GUEST_ is consistent with other #defines such as HV_FEATURE_GUEST_CRASH_MSR_AVAILABLE. The new names also match the TLFS document more accurately, i.e. HvRegisterGuestCrash*. Signed-off-by: Nuno Das Neves <nunodasneves@linux.microsoft.com> Link: https://lore.kernel.org/r/1710285687-9160-1-git-send-email-nunodasneves@linux.microsoft.com Signed-off-by: Wei Liu <wei.liu@kernel.org> Message-ID: <1710285687-9160-1-git-send-email-nunodasneves@linux.microsoft.com>
2024-03-12mshyperv: Introduce hv_get_hypervisor_version functionNuno Das Neves
Introduce x86_64 and arm64 functions to get the hypervisor version information and store it in a structure for simpler parsing. Use the new function to get and parse the version at boot time. While at it, move the printing code to hv_common_init() so it is not duplicated. Signed-off-by: Nuno Das Neves <nunodasneves@linux.microsoft.com> Acked-by: Wei Liu <wei.liu@kernel.org> Reviewed-by: Michael Kelley <mhklinux@outlook.com> Link: https://lore.kernel.org/r/1709852618-29110-1-git-send-email-nunodasneves@linux.microsoft.com Signed-off-by: Wei Liu <wei.liu@kernel.org> Message-ID: <1709852618-29110-1-git-send-email-nunodasneves@linux.microsoft.com>
2023-06-17arm64/hyperv: Use CPUHP_AP_HYPERV_ONLINE state to fix CPU online sequencingMichael Kelley
State CPUHP_AP_HYPERV_ONLINE has been introduced to correctly sequence the initialization of hyperv_pcpu_input_arg. Use this new state for Hyper-V initialization so that hyperv_pcpu_input_arg is allocated early enough. Signed-off-by: Michael Kelley <mikelley@microsoft.com> Reviewed-by: Dexuan Cui <decui@microsoft.com> Link: https://lore.kernel.org/r/1684862062-51576-2-git-send-email-mikelley@microsoft.com Signed-off-by: Wei Liu <wei.liu@kernel.org>
2022-09-28hyperv: simplify and rename generate_guest_idLi kunyu
The generate_guest_id function is more suitable for use after the following modifications. 1. The return value of the function is modified to u64. 2. Remove the d_info1 and d_info2 parameters from the function, keep the u64 type kernel_version parameter. 3. Rename the function to make it clearly a Hyper-V related function, and modify it to hv_generate_guest_id. Signed-off-by: Li kunyu <kunyu@nfschina.com> Reviewed-by: Michael Kelley <mikelley@microsoft.com> Link: https://lore.kernel.org/r/20220928064046.3545-1-kunyu@nfschina.com Signed-off-by: Wei Liu <wei.liu@kernel.org>
2021-08-04arm64: hyperv: Initialize hypervisor on bootMichael Kelley
Add ARM64-specific code to initialize the Hyper-V hypervisor when booting as a guest VM. This code is built only when CONFIG_HYPERV is enabled. Signed-off-by: Michael Kelley <mikelley@microsoft.com> Acked-by: Marc Zyngier <maz@kernel.org> Acked-by: Mark Rutland <mark.rutland@arm.com> Acked-by: Catalin Marinas <catalin.marinas@arm.com> Link: https://lore.kernel.org/r/1628092359-61351-4-git-send-email-mikelley@microsoft.com Signed-off-by: Wei Liu <wei.liu@kernel.org>
2021-08-04arm64: hyperv: Add panic handlerMichael Kelley
Add a function to inform Hyper-V about a guest panic. This code is built only when CONFIG_HYPERV is enabled. Signed-off-by: Michael Kelley <mikelley@microsoft.com> Reviewed-by: Sunil Muthuswamy <sunilmut@microsoft.com> Reviewed-by: Boqun Feng <boqun.feng@gmail.com> Acked-by: Marc Zyngier <maz@kernel.org> Acked-by: Mark Rutland <mark.rutland@arm.com> Acked-by: Catalin Marinas <catalin.marinas@arm.com> Link: https://lore.kernel.org/r/1628092359-61351-3-git-send-email-mikelley@microsoft.com Signed-off-by: Wei Liu <wei.liu@kernel.org>
2021-08-04arm64: hyperv: Add Hyper-V hypercall and register access utilitiesMichael Kelley
hyperv-tlfs.h defines Hyper-V interfaces from the Hyper-V Top Level Functional Spec (TLFS), and #includes the architecture-independent part of hyperv-tlfs.h in include/asm-generic. The published TLFS is distinctly oriented to x86/x64, so the ARM64-specific hyperv-tlfs.h includes information for ARM64 that is not yet formally published. The TLFS is available here: docs.microsoft.com/en-us/virtualization/hyper-v-on-windows/reference/tlfs mshyperv.h defines Linux-specific structures and routines for interacting with Hyper-V on ARM64, and #includes the architecture- independent part of mshyperv.h in include/asm-generic. Use these definitions to provide utility functions to make Hyper-V hypercalls and to get and set Hyper-V provided registers associated with a virtual processor. Signed-off-by: Michael Kelley <mikelley@microsoft.com> Reviewed-by: Sunil Muthuswamy <sunilmut@microsoft.com> Acked-by: Marc Zyngier <maz@kernel.org> Acked-by: Mark Rutland <mark.rutland@arm.com> Acked-by: Catalin Marinas <catalin.marinas@arm.com> Link: https://lore.kernel.org/r/1628092359-61351-2-git-send-email-mikelley@microsoft.com Signed-off-by: Wei Liu <wei.liu@kernel.org>