On Mon, Aug 24, 2020 at 6:48 PM Michael Kelley <mikelley@xxxxxxxxxxxxx> wrote:
>
> /*
> + * This function is invoked via the ACPI clocksource probe mechanism. We
> + * don't actually use any values from the ACPI GTDT table, but we set up
> + * the Hyper-V synthetic clocksource and do other initialization for
> + * interacting with Hyper-V the first time. Using early_initcall to invoke
> + * this function is too late because interrupts are already enabled at that
> + * point, and hv_init_clocksource() must run before interrupts are enabled.
> + *
> + * 1. Setup the guest ID.
> + * 2. Get features and hints info from Hyper-V
> + * 3. Setup per-cpu VP indices.
> + * 4. Initialize the Hyper-V clocksource.
> + */
> +
> +static int __init hyperv_init(struct acpi_table_header *table)
> +{
> + struct hv_get_vp_registers_output result;
> + u32 a, b, c, d;
> + u64 guest_id;
> + int i, cpuhp;
> +
> + /*
> + * 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 -EINVAL;
> +
> + /* 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.misc_features = result.as32.c;
> +
> + hv_get_vpreg_128(HV_REGISTER_ENLIGHTENMENTS, &result);
> + ms_hyperv.hints = result.as32.a;
> +
> + pr_info("Hyper-V: Features 0x%x, hints 0x%x, misc 0x%x\n",
> + ms_hyperv.features, 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);
> +
> + /* Allocate and initialize percpu VP index array */
> + hv_vp_index = kmalloc_array(num_possible_cpus(), sizeof(*hv_vp_index),
> + GFP_KERNEL);
> + if (!hv_vp_index)
> + return -ENOMEM;
> +
> + for (i = 0; i < num_possible_cpus(); i++)
> + hv_vp_index[i] = VP_INVAL;
> +
> + cpuhp = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN,
> + "arm64/hyperv_init:online", hv_cpu_init, NULL);
> + if (cpuhp < 0)
> + goto free_vp_index;
> +
> + hv_init_clocksource();
> + if (hv_stimer_alloc())
> + goto remove_cpuhp_state;
> +
> + hyperv_initialized = true;
> + return 0;
> +
> +remove_cpuhp_state:
> + cpuhp_remove_state(cpuhp);
> +free_vp_index:
> + kfree(hv_vp_index);
> + hv_vp_index = NULL;
> + return -EINVAL;
> +}
> +TIMER_ACPI_DECLARE(hyperv, ACPI_SIG_GTDT, hyperv_init);
I think this has come up before, and I still don't consider it an acceptable
hack to hook platform initialization code into the timer code.
Please split out the timer into a standalone driver in drivers/clocksource
that can get reviewed by the clocksource maintainers.
Arnd
