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From:   Michael Kelley <mikelley@microsoft.com>
To:     will@kernel.org, catalin.marinas@arm.com, mark.rutland@arm.com,
        linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org,
        linux-hyperv@vger.kernel.org, linux-efi@vger.kernel.org,
        arnd@arndb.de, wei.liu@kernel.org, ardb@kernel.org,
        daniel.lezcano@linaro.org, kys@microsoft.com
Cc:     mikelley@microsoft.com
Subject: [PATCH v8 4/6] arm64: hyperv: Initialize hypervisor on boot
Date:   Thu, 18 Feb 2021 15:16:32 -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      | 140 ++++++++++++++++++++++++++++++++++++++
 arch/arm64/include/asm/mshyperv.h |   6 ++
 arch/arm64/kernel/setup.c         |   4 ++
 3 files changed, 150 insertions(+)

diff --git a/arch/arm64/hyperv/mshyperv.c b/arch/arm64/hyperv/mshyperv.c
index d202b4c..c72bc66 100644
--- a/arch/arm64/hyperv/mshyperv.c
+++ b/arch/arm64/hyperv/mshyperv.c
@@ -14,6 +14,146 @@
 #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/log2.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);
+
+/*
+ * As hypercall input and output, align to a power of 2 to ensure they
+ * don't cross a page boundary. Initialize the first element of the
+ * variable size array in the input to ensure enough space is allocated.
+ */
+static struct hv_get_vp_registers_input  input __initdata __aligned(
+		roundup_pow_of_two(sizeof(struct hv_get_vp_registers_input) +
+		sizeof(struct input))) = {.element[0].name0 = 1};
+static struct hv_get_vp_registers_output result __initdata __aligned(
+		roundup_pow_of_two(sizeof(struct hv_get_vp_registers_output)));
+
+void __init hyperv_early_init(void)
+{
+	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, &input, &result);
+	ms_hyperv.features = result.as32.a;
+	ms_hyperv.misc_features = result.as32.c;
+
+	__hv_get_vpreg_128(HV_REGISTER_ENLIGHTENMENTS, &input, &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, &input, &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 u64 hypercall_output __initdata;
+
+static int __init hyperv_init(void)
+{
+	struct hv_get_vpindex_from_apicid_input *input;
+	u64	status;
+	int	i;
+
+	/*
+	 * Hypercall inputs must not cross a page boundary, so allocate
+	 * power of 2 size, which will be aligned to that size.
+	 */
+	input = kzalloc(roundup_pow_of_two(sizeof(input->header) +
+				sizeof(input->element[0])), GFP_KERNEL);
+	if (!input)
+		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) {
+		kfree(input);
+		return -ENOMEM;
+	}
+
+	input->header.partitionid = HV_PARTITION_ID_SELF;
+	for (i = 0; i < hv_max_vp_index; i++) {
+		input->element[0].mpidr = cpu_logical_map(i);
+		status = hv_do_hypercall(HVCALL_VPINDEX_FROM_APICID |
+				HV_HYPERCALL_REP_COMP_1, input,
+				&hypercall_output);
+		if ((status & HV_HYPERCALL_RESULT_MASK) == HV_STATUS_SUCCESS)
+			hv_vp_index[i] = hypercall_output;
+		else {
+			pr_warn("Hyper-V: No VP index for CPU %d MPIDR %llx status %llx\n",
+				i, cpu_logical_map(i), status);
+			hv_vp_index[i] = VP_INVAL;
+		}
+	}
+
+	kfree(input);
+	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 d6ff2ee..55a61a8 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