arm64: hyperv: Initialize hypervisor on boot

Add ARM64-specific code to initialize the Hyper-V
hypervisor when booting as a guest VM.

This code is built only when CONFIG_HYPERV is enabled.

Signed-off-by: Michael Kelley <mikelley@microsoft.com>
Acked-by: Marc Zyngier <maz@kernel.org>
Acked-by: Mark Rutland <mark.rutland@arm.com>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Link: https://lore.kernel.org/r/1628092359-61351-4-git-send-email-mikelley@microsoft.com
Signed-off-by: Wei Liu <wei.liu@kernel.org>

diff --git a/arch/arm64/hyperv/Makefile b/arch/arm64/hyperv/Makefile
index 1697d30ff106f90949e5267b28fa827e5c07fb98..87c31c001da995a6db8a626fe9108b2d50265dc6 100644 (file)
--- a/arch/arm64/hyperv/Makefile
+++ b/arch/arm64/hyperv/Makefile
@@ -1,2 +1,2 @@
 # SPDX-License-Identifier: GPL-2.0
-obj-y          := hv_core.o
+obj-y          := hv_core.o mshyperv.o

diff --git a/arch/arm64/hyperv/mshyperv.c b/arch/arm64/hyperv/mshyperv.c
new file mode 100644 (file)
index 0000000..bbbe351
--- /dev/null
+++ b/arch/arm64/hyperv/mshyperv.c
@@ -0,0 +1,87 @@
+// SPDX-License-Identifier: GPL-2.0
+
+/*
+ * Core routines for interacting with Microsoft's Hyper-V hypervisor,
+ * including hypervisor initialization.
+ *
+ * Copyright (C) 2021, Microsoft, Inc.
+ *
+ * Author : Michael Kelley <mikelley@microsoft.com>
+ */
+
+#include <linux/types.h>
+#include <linux/acpi.h>
+#include <linux/export.h>
+#include <linux/errno.h>
+#include <linux/version.h>
+#include <linux/cpuhotplug.h>
+#include <asm/mshyperv.h>
+
+static bool hyperv_initialized;
+
+static int __init hyperv_init(void)
+{
+       struct hv_get_vp_registers_output       result;
+       u32     a, b, c, d;
+       u64     guest_id;
+       int     ret;
+
+       /*
+        * Allow for a kernel built with CONFIG_HYPERV to be running in
+        * a non-Hyper-V environment, including on DT instead of ACPI.
+        * In such cases, do nothing and return success.
+        */
+       if (acpi_disabled)
+               return 0;
+
+       if (strncmp((char *)&acpi_gbl_FADT.hypervisor_id, "MsHyperV", 8))
+               return 0;
+
+       /* 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);
+
+       /* 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);
+
+       ret = hv_common_init();
+       if (ret)
+               return ret;
+
+       ret = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "arm64/hyperv_init:online",
+                               hv_common_cpu_init, hv_common_cpu_die);
+       if (ret < 0) {
+               hv_common_free();
+               return ret;
+       }
+
+       hyperv_initialized = true;
+       return 0;
+}
+
+early_initcall(hyperv_init);
+
+bool hv_is_hyperv_initialized(void)
+{
+       return hyperv_initialized;
+}
+EXPORT_SYMBOL_GPL(hv_is_hyperv_initialized);