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kelleymh
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arm64: hyperv: Add Hyper-V hypercall and register access utilities
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>
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‎MAINTAINERS‎

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@@ -8154,6 +8154,9 @@ T: git git://git.kernel.org/pub/scm/linux/kernel/git/hyperv/linux.git
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F: Documentation/ABI/stable/sysfs-bus-vmbus
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F: Documentation/ABI/testing/debugfs-hyperv
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F: Documentation/networking/device_drivers/ethernet/microsoft/netvsc.rst
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F: arch/arm64/hyperv
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F: arch/arm64/include/asm/hyperv-tlfs.h
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F: arch/arm64/include/asm/mshyperv.h
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F: arch/x86/hyperv
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F: arch/x86/include/asm/hyperv-tlfs.h
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F: arch/x86/include/asm/mshyperv.h

‎arch/arm64/Kbuild‎

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@@ -3,4 +3,5 @@ obj-y += kernel/ mm/
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obj-$(CONFIG_NET) += net/
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obj-$(CONFIG_KVM) += kvm/
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obj-$(CONFIG_XEN) += xen/
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obj-$(subst m,y,$(CONFIG_HYPERV)) += hyperv/
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obj-$(CONFIG_CRYPTO) += crypto/

‎arch/arm64/hyperv/Makefile‎

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# SPDX-License-Identifier: GPL-2.0
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obj-y := hv_core.o

‎arch/arm64/hyperv/hv_core.c‎

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// SPDX-License-Identifier: GPL-2.0
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/*
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* Low level utility routines for interacting with Hyper-V.
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*
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* Copyright (C) 2021, Microsoft, Inc.
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*
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* Author : Michael Kelley <mikelley@microsoft.com>
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*/
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#include <linux/types.h>
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#include <linux/export.h>
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#include <linux/mm.h>
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#include <linux/hyperv.h>
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#include <linux/arm-smccc.h>
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#include <linux/module.h>
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#include <asm-generic/bug.h>
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#include <asm/hyperv-tlfs.h>
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#include <asm/mshyperv.h>
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/*
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* hv_do_hypercall- Invoke the specified hypercall
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*/
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u64 hv_do_hypercall(u64 control, void *input, void *output)
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{
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struct arm_smccc_res res;
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u64 input_address;
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u64 output_address;
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input_address = input ? virt_to_phys(input) : 0;
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output_address = output ? virt_to_phys(output) : 0;
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arm_smccc_1_1_hvc(HV_FUNC_ID, control,
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input_address, output_address, &res);
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return res.a0;
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}
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EXPORT_SYMBOL_GPL(hv_do_hypercall);
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/*
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* hv_do_fast_hypercall8 -- Invoke the specified hypercall
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* with arguments in registers instead of physical memory.
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* Avoids the overhead of virt_to_phys for simple hypercalls.
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*/
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u64 hv_do_fast_hypercall8(u16 code, u64 input)
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{
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struct arm_smccc_res res;
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u64 control;
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control = (u64)code | HV_HYPERCALL_FAST_BIT;
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arm_smccc_1_1_hvc(HV_FUNC_ID, control, input, &res);
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return res.a0;
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}
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EXPORT_SYMBOL_GPL(hv_do_fast_hypercall8);
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/*
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* Set a single VP register to a 64-bit value.
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*/
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void hv_set_vpreg(u32 msr, u64 value)
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{
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struct arm_smccc_res res;
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arm_smccc_1_1_hvc(
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HV_FUNC_ID,
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HVCALL_SET_VP_REGISTERS | HV_HYPERCALL_FAST_BIT |
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HV_HYPERCALL_REP_COMP_1,
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HV_PARTITION_ID_SELF,
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HV_VP_INDEX_SELF,
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msr,
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0,
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value,
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0,
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&res);
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/*
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* Something is fundamentally broken in the hypervisor if
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* setting a VP register fails. There's really no way to
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* continue as a guest VM, so panic.
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*/
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BUG_ON((res.a0 & HV_HYPERCALL_RESULT_MASK) != HV_STATUS_SUCCESS);
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}
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EXPORT_SYMBOL_GPL(hv_set_vpreg);
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/*
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* Get the value of a single VP register. One version
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* returns just 64 bits and another returns the full 128 bits.
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* The two versions are separate to avoid complicating the
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* calling sequence for the more frequently used 64 bit version.
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*/
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void hv_get_vpreg_128(u32 msr, struct hv_get_vp_registers_output *result)
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{
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struct arm_smccc_res res;
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arm_smccc_1_1_hvc_reg("r5", "r6", "r7",
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HV_FUNC_ID,
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HVCALL_GET_VP_REGISTERS | HV_HYPERCALL_FAST_BIT |
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HV_HYPERCALL_REP_COMP_1,
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HV_PARTITION_ID_SELF,
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HV_VP_INDEX_SELF,
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msr,
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0,
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&res);
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/*
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* Something is fundamentally broken in the hypervisor if
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* getting a VP register fails. There's really no way to
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* continue as a guest VM, so panic.
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*/
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BUG_ON((res.a0 & HV_HYPERCALL_RESULT_MASK) != HV_STATUS_SUCCESS);
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result->as64.low = res.a2; /* r6 */
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result->as64.high = res.a3; /* r7 */
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}
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EXPORT_SYMBOL_GPL(hv_get_vpreg_128);
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u64 hv_get_vpreg(u32 msr)
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{
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struct hv_get_vp_registers_output output;
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hv_get_vpreg_128(msr, &output);
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return output.as64.low;
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}
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EXPORT_SYMBOL_GPL(hv_get_vpreg);

‎arch/arm64/include/asm/hyperv-tlfs.h‎

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/* SPDX-License-Identifier: GPL-2.0 */
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/*
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* This file contains definitions from the Hyper-V Hypervisor Top-Level
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* Functional Specification (TLFS):
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* https://docs.microsoft.com/en-us/virtualization/hyper-v-on-windows/reference/tlfs
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*
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* Copyright (C) 2021, Microsoft, Inc.
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*
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* Author : Michael Kelley <mikelley@microsoft.com>
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*/
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#ifndef _ASM_HYPERV_TLFS_H
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#define _ASM_HYPERV_TLFS_H
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#include <linux/types.h>
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/*
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* All data structures defined in the TLFS that are shared between Hyper-V
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* and a guest VM use Little Endian byte ordering. This matches the default
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* byte ordering of Linux running on ARM64, so no special handling is required.
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*/
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/*
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* These Hyper-V registers provide information equivalent to the CPUID
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* instruction on x86/x64.
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*/
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#define HV_REGISTER_HYPERVISOR_VERSION 0x00000100 /*CPUID 0x40000002 */
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#define HV_REGISTER_FEATURES 0x00000200 /*CPUID 0x40000003 */
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#define HV_REGISTER_ENLIGHTENMENTS 0x00000201 /*CPUID 0x40000004 */
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/*
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* Group C Features. See the asm-generic version of hyperv-tlfs.h
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* for a description of Feature Groups.
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*/
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/* Crash MSRs available */
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#define HV_FEATURE_GUEST_CRASH_MSR_AVAILABLE BIT(8)
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/* STIMER direct mode is available */
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#define HV_STIMER_DIRECT_MODE_AVAILABLE BIT(13)
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/*
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* Synthetic register definitions equivalent to MSRs on x86/x64
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*/
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#define HV_REGISTER_CRASH_P0 0x00000210
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#define HV_REGISTER_CRASH_P1 0x00000211
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#define HV_REGISTER_CRASH_P2 0x00000212
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#define HV_REGISTER_CRASH_P3 0x00000213
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#define HV_REGISTER_CRASH_P4 0x00000214
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#define HV_REGISTER_CRASH_CTL 0x00000215
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#define HV_REGISTER_GUEST_OSID 0x00090002
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#define HV_REGISTER_VP_INDEX 0x00090003
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#define HV_REGISTER_TIME_REF_COUNT 0x00090004
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#define HV_REGISTER_REFERENCE_TSC 0x00090017
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#define HV_REGISTER_SINT0 0x000A0000
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#define HV_REGISTER_SCONTROL 0x000A0010
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#define HV_REGISTER_SIEFP 0x000A0012
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#define HV_REGISTER_SIMP 0x000A0013
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#define HV_REGISTER_EOM 0x000A0014
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#define HV_REGISTER_STIMER0_CONFIG 0x000B0000
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#define HV_REGISTER_STIMER0_COUNT 0x000B0001
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#include <asm-generic/hyperv-tlfs.h>
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#endif

‎arch/arm64/include/asm/mshyperv.h‎

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/* SPDX-License-Identifier: GPL-2.0 */
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/*
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* Linux-specific definitions for managing interactions with Microsoft's
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* Hyper-V hypervisor. The definitions in this file are specific to
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* the ARM64 architecture. See include/asm-generic/mshyperv.h for
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* definitions are that architecture independent.
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*
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* Definitions that are specified in the Hyper-V Top Level Functional
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* Spec (TLFS) should not go in this file, but should instead go in
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* hyperv-tlfs.h.
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*
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* Copyright (C) 2021, Microsoft, Inc.
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*
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* Author : Michael Kelley <mikelley@microsoft.com>
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*/
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#ifndef _ASM_MSHYPERV_H
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#define _ASM_MSHYPERV_H
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#include <linux/types.h>
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#include <linux/arm-smccc.h>
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#include <asm/hyperv-tlfs.h>
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/*
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* Declare calls to get and set Hyper-V VP register values on ARM64, which
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* requires a hypercall.
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*/
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extern void hv_set_vpreg(u32 reg, u64 value);
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extern u64 hv_get_vpreg(u32 reg);
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extern void hv_get_vpreg_128(u32 reg, struct hv_get_vp_registers_output *result);
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static inline void hv_set_register(unsigned int reg, u64 value)
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{
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hv_set_vpreg(reg, value);
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}
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static inline u64 hv_get_register(unsigned int reg)
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{
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return hv_get_vpreg(reg);
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}
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/* SMCCC hypercall parameters */
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#define HV_SMCCC_FUNC_NUMBER 1
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#define HV_FUNC_ID ARM_SMCCC_CALL_VAL( \
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ARM_SMCCC_STD_CALL, \
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ARM_SMCCC_SMC_64, \
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ARM_SMCCC_OWNER_VENDOR_HYP, \
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HV_SMCCC_FUNC_NUMBER)
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#include <asm-generic/mshyperv.h>
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#endif

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