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From:   Michael Kelley <mikelley@microsoft.com>
To:     will@kernel.org, catalin.marinas@arm.com, mark.rutland@arm.com,
        lorenzo.pieralisi@arm.com, sudeep.holla@arm.com,
        linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org,
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        arnd@arndb.de, wei.liu@kernel.org, ardb@kernel.org,
        daniel.lezcano@linaro.org, kys@microsoft.com
Cc:     mikelley@microsoft.com
Subject: [PATCH v9 5/7] arm64: hyperv: Initialize hypervisor on boot
Date:   Mon,  8 Mar 2021 11:57:17 -0800
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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      | 119 ++++++++++++++++++++++++++++++++++++++
 arch/arm64/include/asm/mshyperv.h |   6 ++
 arch/arm64/kernel/setup.c         |   4 ++
 3 files changed, 129 insertions(+)

diff --git a/arch/arm64/hyperv/mshyperv.c b/arch/arm64/hyperv/mshyperv.c
index d202b4c..125e83e 100644
--- a/arch/arm64/hyperv/mshyperv.c
+++ b/arch/arm64/hyperv/mshyperv.c
@@ -14,6 +14,125 @@
 #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);
+
+u32	*hv_vp_index;
+EXPORT_SYMBOL_GPL(hv_vp_index);
+
+u32	hv_max_vp_index;
+EXPORT_SYMBOL_GPL(hv_max_vp_index);
+
+static int hv_cpu_init(unsigned int cpu)
+{
+	hv_vp_index[cpu] = hv_get_vpreg(HV_REGISTER_VP_INDEX);
+	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.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);
+
+	hyperv_initialized = true;
+}
+
+static int __init hyperv_init(void)
+{
+	int	i;
+
+	/* 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) {
+		hv_max_vp_index = 0;
+		return -ENOMEM;
+	}
+
+	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) {
+		hv_max_vp_index = 0;
+		kfree(hv_vp_index);
+		hv_vp_index = NULL;
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+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);
 
 /*
  * 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 c18aacd..1df8285 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;
@@ -340,6 +341,9 @@ 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