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    Subject[PATCH v10 5/7] arm64: hyperv: Initialize hypervisor on boot
    Date
    Add ARM64-specific code to initialize the Hyper-V
    hypervisor when booting as a guest VM. Provide functions
    and data structures indicating hypervisor status that
    are needed by VMbus driver.

    This code is built only when CONFIG_HYPERV is enabled.

    Signed-off-by: Michael Kelley <mikelley@microsoft.com>
    ---
    arch/arm64/hyperv/mshyperv.c | 152 ++++++++++++++++++++++++++++++++++++++
    arch/arm64/include/asm/mshyperv.h | 6 ++
    arch/arm64/kernel/setup.c | 4 +
    3 files changed, 162 insertions(+)

    diff --git a/arch/arm64/hyperv/mshyperv.c b/arch/arm64/hyperv/mshyperv.c
    index d202b4c..95f7e4e 100644
    --- a/arch/arm64/hyperv/mshyperv.c
    +++ b/arch/arm64/hyperv/mshyperv.c
    @@ -14,6 +14,158 @@
    #include <linux/types.h>
    #include <linux/export.h>
    #include <linux/ptrace.h>
    +#include <linux/errno.h>
    +#include <linux/acpi.h>
    +#include <linux/version.h>
    +#include <linux/cpuhotplug.h>
    +#include <linux/slab.h>
    +#include <linux/cpumask.h>
    +#include <asm/mshyperv.h>
    +
    +static bool hyperv_initialized;
    +struct ms_hyperv_info ms_hyperv __ro_after_init;
    +EXPORT_SYMBOL_GPL(ms_hyperv);
    +
    +bool hv_root_partition;
    +EXPORT_SYMBOL_GPL(hv_root_partition);
    +
    +u32 *hv_vp_index;
    +EXPORT_SYMBOL_GPL(hv_vp_index);
    +
    +u32 hv_max_vp_index;
    +EXPORT_SYMBOL_GPL(hv_max_vp_index);
    +
    +void __percpu **hyperv_pcpu_input_arg;
    +EXPORT_SYMBOL_GPL(hyperv_pcpu_input_arg);
    +
    +static int hv_cpu_init(unsigned int cpu)
    +{
    + void **input_arg = (void **)this_cpu_ptr(hyperv_pcpu_input_arg);
    +
    + hv_vp_index[cpu] = hv_get_vpreg(HV_REGISTER_VP_INDEX);
    +
    + *input_arg = kmalloc(HV_HYP_PAGE_SIZE, GFP_KERNEL);
    + if (!(*input_arg))
    + return -ENOMEM;
    +
    + return 0;
    +}
    +
    +void __init hyperv_early_init(void)
    +{
    + struct hv_get_vp_registers_output result;
    + u32 a, b, c, d;
    + u64 guest_id;
    +
    + /*
    + * If we're in a VM on Hyper-V, the ACPI hypervisor_id field will
    + * have the string "MsHyperV".
    + */
    + if (strncmp((char *)&acpi_gbl_FADT.hypervisor_id, "MsHyperV", 8))
    + return;
    +
    + /* Setup the guest ID */
    + guest_id = generate_guest_id(0, LINUX_VERSION_CODE, 0);
    + hv_set_vpreg(HV_REGISTER_GUEST_OSID, guest_id);
    +
    + /* Get the features and hints from Hyper-V */
    + hv_get_vpreg_128(HV_REGISTER_FEATURES, &result);
    + ms_hyperv.features = result.as32.a;
    + ms_hyperv.priv_high = result.as32.b;
    + ms_hyperv.misc_features = result.as32.c;
    +
    + hv_get_vpreg_128(HV_REGISTER_ENLIGHTENMENTS, &result);
    + ms_hyperv.hints = result.as32.a;
    +
    + pr_info("Hyper-V: privilege flags low 0x%x, high 0x%x, hints 0x%x, misc 0x%x\n",
    + ms_hyperv.features, ms_hyperv.priv_high, ms_hyperv.hints,
    + ms_hyperv.misc_features);
    +
    + /*
    + * If Hyper-V has crash notifications, set crash_kexec_post_notifiers
    + * so that we will report the panic to Hyper-V before running kdump.
    + */
    + if (ms_hyperv.misc_features & HV_FEATURE_GUEST_CRASH_MSR_AVAILABLE)
    + crash_kexec_post_notifiers = true;
    +
    + /* Get information about the Hyper-V host version */
    + hv_get_vpreg_128(HV_REGISTER_HYPERVISOR_VERSION, &result);
    + a = result.as32.a;
    + b = result.as32.b;
    + c = result.as32.c;
    + d = result.as32.d;
    + pr_info("Hyper-V: Host Build %d.%d.%d.%d-%d-%d\n",
    + b >> 16, b & 0xFFFF, a, d & 0xFFFFFF, c, d >> 24);
    +
    + hyperv_initialized = true;
    +}
    +
    +static int __init hyperv_init(void)
    +{
    + int i, ret;
    +
    + hyperv_pcpu_input_arg = alloc_percpu(void *);
    + if (!hyperv_pcpu_input_arg)
    + return -ENOMEM;
    +
    + /* Allocate and initialize percpu VP index array */
    + hv_max_vp_index = num_possible_cpus();
    + hv_vp_index = kmalloc_array(hv_max_vp_index, sizeof(*hv_vp_index),
    + GFP_KERNEL);
    + if (!hv_vp_index) {
    + ret = -ENOMEM;
    + goto free_input_arg;
    + }
    +
    + for (i = 0; i < hv_max_vp_index; i++)
    + hv_vp_index[i] = VP_INVAL;
    +
    + if (cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "arm64/hyperv_init:online",
    + hv_cpu_init, NULL) < 0) {
    + ret = -EINVAL;
    + goto free_vp_index;
    + }
    +
    + return 0;
    +
    +free_vp_index:
    + kfree(hv_vp_index);
    + hv_vp_index = NULL;
    +
    +free_input_arg:
    + hv_max_vp_index = 0;
    + free_percpu(hyperv_pcpu_input_arg);
    + hyperv_pcpu_input_arg = NULL;
    + return ret;
    +}
    +
    +early_initcall(hyperv_init);
    +
    +/* This routine is called before kexec/kdump. It does required cleanup. */
    +void hyperv_cleanup(void)
    +{
    + hv_set_vpreg(HV_REGISTER_GUEST_OSID, 0);
    +
    +}
    +EXPORT_SYMBOL_GPL(hyperv_cleanup);
    +
    +bool hv_is_hyperv_initialized(void)
    +{
    + return hyperv_initialized;
    +}
    +EXPORT_SYMBOL_GPL(hv_is_hyperv_initialized);
    +
    +bool hv_is_hibernation_supported(void)
    +{
    + return false;
    +}
    +EXPORT_SYMBOL_GPL(hv_is_hibernation_supported);
    +
    +bool hv_is_isolation_supported(void)
    +{
    + return false;
    +}
    +EXPORT_SYMBOL_GPL(hv_is_isolation_supported);

    /*
    * The VMbus handler functions are no-ops on ARM64 because
    diff --git a/arch/arm64/include/asm/mshyperv.h b/arch/arm64/include/asm/mshyperv.h
    index b17299c..86ca5c5 100644
    --- a/arch/arm64/include/asm/mshyperv.h
    +++ b/arch/arm64/include/asm/mshyperv.h
    @@ -23,6 +23,12 @@
    #include <asm/hyperv-tlfs.h>
    #include <clocksource/arm_arch_timer.h>

    +#if IS_ENABLED(CONFIG_HYPERV)
    +void __init hyperv_early_init(void);
    +#else
    +static inline void hyperv_early_init(void) {};
    +#endif
    +
    /*
    * Declare calls to get and set Hyper-V VP register values on ARM64, which
    * requires a hypercall.
    diff --git a/arch/arm64/kernel/setup.c b/arch/arm64/kernel/setup.c
    index 61845c0..7b17d6a 100644
    --- a/arch/arm64/kernel/setup.c
    +++ b/arch/arm64/kernel/setup.c
    @@ -49,6 +49,7 @@
    #include <asm/traps.h>
    #include <asm/efi.h>
    #include <asm/xen/hypervisor.h>
    +#include <asm/mshyperv.h>
    #include <asm/mmu_context.h>

    static int num_standard_resources;
    @@ -355,6 +356,9 @@ void __init __no_sanitize_address setup_arch(char **cmdline_p)
    if (acpi_disabled)
    unflatten_device_tree();

    + /* Do after acpi_boot_table_init() so local FADT is available */
    + hyperv_early_init();
    +
    bootmem_init();

    kasan_init();
    --
    1.8.3.1
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