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    Subject[PATCH v11 1/5] arm64: hyperv: Add Hyper-V hypercall and register access utilities
    Date
    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>

    ---
    MAINTAINERS | 3 +
    arch/arm64/Kbuild | 1 +
    arch/arm64/hyperv/Makefile | 2 +
    arch/arm64/hyperv/hv_core.c | 129 +++++++++++++++++++++++++++++++++++
    arch/arm64/include/asm/hyperv-tlfs.h | 69 +++++++++++++++++++
    arch/arm64/include/asm/mshyperv.h | 54 +++++++++++++++
    6 files changed, 258 insertions(+)
    create mode 100644 arch/arm64/hyperv/Makefile
    create mode 100644 arch/arm64/hyperv/hv_core.c
    create mode 100644 arch/arm64/include/asm/hyperv-tlfs.h
    create mode 100644 arch/arm64/include/asm/mshyperv.h

    diff --git a/MAINTAINERS b/MAINTAINERS
    index 6993219..8f6f429 100644
    --- a/MAINTAINERS
    +++ b/MAINTAINERS
    @@ -8608,6 +8608,9 @@ T: git git://git.kernel.org/pub/scm/linux/kernel/git/hyperv/linux.git
    F: Documentation/ABI/stable/sysfs-bus-vmbus
    F: Documentation/ABI/testing/debugfs-hyperv
    F: Documentation/networking/device_drivers/ethernet/microsoft/netvsc.rst
    +F: arch/arm64/hyperv
    +F: arch/arm64/include/asm/hyperv-tlfs.h
    +F: arch/arm64/include/asm/mshyperv.h
    F: arch/x86/hyperv
    F: arch/x86/include/asm/hyperv-tlfs.h
    F: arch/x86/include/asm/mshyperv.h
    diff --git a/arch/arm64/Kbuild b/arch/arm64/Kbuild
    index 7b393cf..ea7ab4c 100644
    --- a/arch/arm64/Kbuild
    +++ b/arch/arm64/Kbuild
    @@ -2,4 +2,5 @@
    obj-y += kernel/ mm/ net/
    obj-$(CONFIG_KVM) += kvm/
    obj-$(CONFIG_XEN) += xen/
    +obj-$(subst m,y,$(CONFIG_HYPERV)) += hyperv/
    obj-$(CONFIG_CRYPTO) += crypto/
    diff --git a/arch/arm64/hyperv/Makefile b/arch/arm64/hyperv/Makefile
    new file mode 100644
    index 0000000..1697d30
    --- /dev/null
    +++ b/arch/arm64/hyperv/Makefile
    @@ -0,0 +1,2 @@
    +# SPDX-License-Identifier: GPL-2.0
    +obj-y := hv_core.o
    diff --git a/arch/arm64/hyperv/hv_core.c b/arch/arm64/hyperv/hv_core.c
    new file mode 100644
    index 0000000..4c5dc0f
    --- /dev/null
    +++ b/arch/arm64/hyperv/hv_core.c
    @@ -0,0 +1,129 @@
    +// SPDX-License-Identifier: GPL-2.0
    +
    +/*
    + * Low level utility routines for interacting with Hyper-V.
    + *
    + * Copyright (C) 2021, Microsoft, Inc.
    + *
    + * Author : Michael Kelley <mikelley@microsoft.com>
    + */
    +
    +#include <linux/types.h>
    +#include <linux/export.h>
    +#include <linux/mm.h>
    +#include <linux/hyperv.h>
    +#include <linux/arm-smccc.h>
    +#include <linux/module.h>
    +#include <asm-generic/bug.h>
    +#include <asm/hyperv-tlfs.h>
    +#include <asm/mshyperv.h>
    +
    +/*
    + * hv_do_hypercall- Invoke the specified hypercall
    + */
    +u64 hv_do_hypercall(u64 control, void *input, void *output)
    +{
    + struct arm_smccc_res res;
    + u64 input_address;
    + u64 output_address;
    +
    + input_address = input ? virt_to_phys(input) : 0;
    + output_address = output ? virt_to_phys(output) : 0;
    +
    + arm_smccc_1_1_hvc(HV_FUNC_ID, control,
    + input_address, output_address, &res);
    + return res.a0;
    +}
    +EXPORT_SYMBOL_GPL(hv_do_hypercall);
    +
    +/*
    + * hv_do_fast_hypercall8 -- Invoke the specified hypercall
    + * with arguments in registers instead of physical memory.
    + * Avoids the overhead of virt_to_phys for simple hypercalls.
    + */
    +
    +u64 hv_do_fast_hypercall8(u16 code, u64 input)
    +{
    + struct arm_smccc_res res;
    + u64 control;
    +
    + control = (u64)code | HV_HYPERCALL_FAST_BIT;
    +
    + arm_smccc_1_1_hvc(HV_FUNC_ID, control, input, &res);
    + return res.a0;
    +}
    +EXPORT_SYMBOL_GPL(hv_do_fast_hypercall8);
    +
    +/*
    + * Set a single VP register to a 64-bit value.
    + */
    +void hv_set_vpreg(u32 msr, u64 value)
    +{
    + struct arm_smccc_res res;
    +
    + arm_smccc_1_1_hvc(HV_FUNC_ID,
    + HVCALL_SET_VP_REGISTERS | HV_HYPERCALL_FAST_BIT |
    + HV_HYPERCALL_REP_COMP_1,
    + HV_PARTITION_ID_SELF,
    + HV_VP_INDEX_SELF,
    + msr,
    + 0,
    + value,
    + 0,
    + &res);
    +
    + /*
    + * Something is fundamentally broken in the hypervisor if
    + * setting a VP register fails. There's really no way to
    + * continue as a guest VM, so panic.
    + */
    + BUG_ON(!hv_result_success(res.a0));
    +}
    +EXPORT_SYMBOL_GPL(hv_set_vpreg);
    +
    +/*
    + * Get the value of a single VP register. One version
    + * returns just 64 bits and another returns the full 128 bits.
    + * The two versions are separate to avoid complicating the
    + * calling sequence for the more frequently used 64 bit version.
    + */
    +
    +void hv_get_vpreg_128(u32 msr, struct hv_get_vp_registers_output *result)
    +{
    + struct arm_smccc_1_2_regs args;
    + struct arm_smccc_1_2_regs res;
    +
    + args.a0 = HV_FUNC_ID;
    + args.a1 = HVCALL_GET_VP_REGISTERS | HV_HYPERCALL_FAST_BIT |
    + HV_HYPERCALL_REP_COMP_1;
    + args.a2 = HV_PARTITION_ID_SELF;
    + args.a3 = HV_VP_INDEX_SELF;
    + args.a4 = msr;
    +
    + /*
    + * Use the SMCCC 1.2 interface because the results are in registers
    + * beyond X0-X3.
    + */
    + arm_smccc_1_2_hvc(&args, &res);
    +
    + /*
    + * Something is fundamentally broken in the hypervisor if
    + * getting a VP register fails. There's really no way to
    + * continue as a guest VM, so panic.
    + */
    + BUG_ON(!hv_result_success(res.a0));
    +
    + result->as64.low = res.a6;
    + result->as64.high = res.a7;
    +}
    +EXPORT_SYMBOL_GPL(hv_get_vpreg_128);
    +
    +u64 hv_get_vpreg(u32 msr)
    +{
    + struct hv_get_vp_registers_output output;
    +
    + hv_get_vpreg_128(msr, &output);
    +
    + return output.as64.low;
    +}
    +EXPORT_SYMBOL_GPL(hv_get_vpreg);
    diff --git a/arch/arm64/include/asm/hyperv-tlfs.h b/arch/arm64/include/asm/hyperv-tlfs.h
    new file mode 100644
    index 0000000..4d964a7
    --- /dev/null
    +++ b/arch/arm64/include/asm/hyperv-tlfs.h
    @@ -0,0 +1,69 @@
    +/* SPDX-License-Identifier: GPL-2.0 */
    +
    +/*
    + * This file contains definitions from the Hyper-V Hypervisor Top-Level
    + * Functional Specification (TLFS):
    + * https://docs.microsoft.com/en-us/virtualization/hyper-v-on-windows/reference/tlfs
    + *
    + * Copyright (C) 2021, Microsoft, Inc.
    + *
    + * Author : Michael Kelley <mikelley@microsoft.com>
    + */
    +
    +#ifndef _ASM_HYPERV_TLFS_H
    +#define _ASM_HYPERV_TLFS_H
    +
    +#include <linux/types.h>
    +
    +/*
    + * All data structures defined in the TLFS that are shared between Hyper-V
    + * and a guest VM use Little Endian byte ordering. This matches the default
    + * byte ordering of Linux running on ARM64, so no special handling is required.
    + */
    +
    +/*
    + * These Hyper-V registers provide information equivalent to the CPUID
    + * instruction on x86/x64.
    + */
    +#define HV_REGISTER_HYPERVISOR_VERSION 0x00000100 /*CPUID 0x40000002 */
    +#define HV_REGISTER_FEATURES 0x00000200 /*CPUID 0x40000003 */
    +#define HV_REGISTER_ENLIGHTENMENTS 0x00000201 /*CPUID 0x40000004 */
    +
    +/*
    + * Group C Features. See the asm-generic version of hyperv-tlfs.h
    + * for a description of Feature Groups.
    + */
    +
    +/* Crash MSRs available */
    +#define HV_FEATURE_GUEST_CRASH_MSR_AVAILABLE BIT(8)
    +
    +/* STIMER direct mode is available */
    +#define HV_STIMER_DIRECT_MODE_AVAILABLE BIT(13)
    +
    +/*
    + * Synthetic register definitions equivalent to MSRs on x86/x64
    + */
    +#define HV_REGISTER_CRASH_P0 0x00000210
    +#define HV_REGISTER_CRASH_P1 0x00000211
    +#define HV_REGISTER_CRASH_P2 0x00000212
    +#define HV_REGISTER_CRASH_P3 0x00000213
    +#define HV_REGISTER_CRASH_P4 0x00000214
    +#define HV_REGISTER_CRASH_CTL 0x00000215
    +
    +#define HV_REGISTER_GUEST_OSID 0x00090002
    +#define HV_REGISTER_VP_INDEX 0x00090003
    +#define HV_REGISTER_TIME_REF_COUNT 0x00090004
    +#define HV_REGISTER_REFERENCE_TSC 0x00090017
    +
    +#define HV_REGISTER_SINT0 0x000A0000
    +#define HV_REGISTER_SCONTROL 0x000A0010
    +#define HV_REGISTER_SIEFP 0x000A0012
    +#define HV_REGISTER_SIMP 0x000A0013
    +#define HV_REGISTER_EOM 0x000A0014
    +
    +#define HV_REGISTER_STIMER0_CONFIG 0x000B0000
    +#define HV_REGISTER_STIMER0_COUNT 0x000B0001
    +
    +#include <asm-generic/hyperv-tlfs.h>
    +
    +#endif
    diff --git a/arch/arm64/include/asm/mshyperv.h b/arch/arm64/include/asm/mshyperv.h
    new file mode 100644
    index 0000000..20070a8
    --- /dev/null
    +++ b/arch/arm64/include/asm/mshyperv.h
    @@ -0,0 +1,54 @@
    +/* SPDX-License-Identifier: GPL-2.0 */
    +
    +/*
    + * Linux-specific definitions for managing interactions with Microsoft's
    + * Hyper-V hypervisor. The definitions in this file are specific to
    + * the ARM64 architecture. See include/asm-generic/mshyperv.h for
    + * definitions are that architecture independent.
    + *
    + * Definitions that are specified in the Hyper-V Top Level Functional
    + * Spec (TLFS) should not go in this file, but should instead go in
    + * hyperv-tlfs.h.
    + *
    + * Copyright (C) 2021, Microsoft, Inc.
    + *
    + * Author : Michael Kelley <mikelley@microsoft.com>
    + */
    +
    +#ifndef _ASM_MSHYPERV_H
    +#define _ASM_MSHYPERV_H
    +
    +#include <linux/types.h>
    +#include <linux/arm-smccc.h>
    +#include <asm/hyperv-tlfs.h>
    +
    +/*
    + * Declare calls to get and set Hyper-V VP register values on ARM64, which
    + * requires a hypercall.
    + */
    +
    +void hv_set_vpreg(u32 reg, u64 value);
    +u64 hv_get_vpreg(u32 reg);
    +void hv_get_vpreg_128(u32 reg, struct hv_get_vp_registers_output *result);
    +
    +static inline void hv_set_register(unsigned int reg, u64 value)
    +{
    + hv_set_vpreg(reg, value);
    +}
    +
    +static inline u64 hv_get_register(unsigned int reg)
    +{
    + return hv_get_vpreg(reg);
    +}
    +
    +/* SMCCC hypercall parameters */
    +#define HV_SMCCC_FUNC_NUMBER 1
    +#define HV_FUNC_ID ARM_SMCCC_CALL_VAL( \
    + ARM_SMCCC_STD_CALL, \
    + ARM_SMCCC_SMC_64, \
    + ARM_SMCCC_OWNER_VENDOR_HYP, \
    + HV_SMCCC_FUNC_NUMBER)
    +
    +#include <asm-generic/mshyperv.h>
    +
    +#endif
    --
    1.8.3.1
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