[PATCH v2] mshyperv: Introduce hv_get_hypervisor_version function

[Nuno Das Neves <nunodasneves@linux.microsoft.com>]

Introduce x86_64 and arm64 functions to get the hypervisor version
information and store it in a structure for simpler parsing.

Use the new function to get and parse the version at boot time. While at
it, move the printing code to hv_common_init() so it is not duplicated.

Signed-off-by: Nuno Das Neves <nunodasneves@linux.microsoft.com>
Acked-by: Wei Liu <wei.liu@kernel.org>
---
Changes since v1:
- Amend commit message
- Address minor style issues
- Remove unneeded EXPORT_SYMBOL_GPL(hv_get_hypervisor_version)
---
 arch/arm64/hyperv/mshyperv.c      | 18 ++++++++--------
 arch/x86/kernel/cpu/mshyperv.c    | 34 ++++++++++++++-----------------
 drivers/hv/hv_common.c            |  8 ++++++++
 include/asm-generic/hyperv-tlfs.h | 23 +++++++++++++++++++++
 include/asm-generic/mshyperv.h    |  1 +
 5 files changed, 55 insertions(+), 29 deletions(-)

diff --git a/arch/arm64/hyperv/mshyperv.c b/arch/arm64/hyperv/mshyperv.c
index f1b8a04ee9f2..99362716ac87 100644
--- a/arch/arm64/hyperv/mshyperv.c
+++ b/arch/arm64/hyperv/mshyperv.c
@@ -19,10 +19,17 @@
 
 static bool hyperv_initialized;
 
+int hv_get_hypervisor_version(union hv_hypervisor_version_info *info)
+{
+	hv_get_vpreg_128(HV_REGISTER_HYPERVISOR_VERSION,
+			 (struct hv_get_vp_registers_output *)info);
+
+	return 0;
+}
+
 static int __init hyperv_init(void)
 {
 	struct hv_get_vp_registers_output	result;
-	u32	a, b, c, d;
 	u64	guest_id;
 	int	ret;
 
@@ -54,15 +61,6 @@ static int __init hyperv_init(void)
 		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;
diff --git a/arch/x86/kernel/cpu/mshyperv.c b/arch/x86/kernel/cpu/mshyperv.c
index d306f6184cee..56e731d8f513 100644
--- a/arch/x86/kernel/cpu/mshyperv.c
+++ b/arch/x86/kernel/cpu/mshyperv.c
@@ -350,13 +350,24 @@ static void __init reduced_hw_init(void)
 	x86_init.irqs.pre_vector_init	= x86_init_noop;
 }
 
+int hv_get_hypervisor_version(union hv_hypervisor_version_info *info)
+{
+	unsigned int hv_max_functions;
+
+	hv_max_functions = cpuid_eax(HYPERV_CPUID_VENDOR_AND_MAX_FUNCTIONS);
+	if (hv_max_functions < HYPERV_CPUID_VERSION) {
+		pr_err("%s: Could not detect Hyper-V version\n", __func__);
+		return -ENODEV;
+	}
+
+	cpuid(HYPERV_CPUID_VERSION, &info->eax, &info->ebx, &info->ecx, &info->edx);
+
+	return 0;
+}
+
 static void __init ms_hyperv_init_platform(void)
 {
 	int hv_max_functions_eax;
-	int hv_host_info_eax;
-	int hv_host_info_ebx;
-	int hv_host_info_ecx;
-	int hv_host_info_edx;
 
 #ifdef CONFIG_PARAVIRT
 	pv_info.name = "Hyper-V";
@@ -407,21 +418,6 @@ static void __init ms_hyperv_init_platform(void)
 		pr_info("Hyper-V: running on a nested hypervisor\n");
 	}
 
-	/*
-	 * Extract host information.
-	 */
-	if (hv_max_functions_eax >= HYPERV_CPUID_VERSION) {
-		hv_host_info_eax = cpuid_eax(HYPERV_CPUID_VERSION);
-		hv_host_info_ebx = cpuid_ebx(HYPERV_CPUID_VERSION);
-		hv_host_info_ecx = cpuid_ecx(HYPERV_CPUID_VERSION);
-		hv_host_info_edx = cpuid_edx(HYPERV_CPUID_VERSION);
-
-		pr_info("Hyper-V: Host Build %d.%d.%d.%d-%d-%d\n",
-			hv_host_info_ebx >> 16, hv_host_info_ebx & 0xFFFF,
-			hv_host_info_eax, hv_host_info_edx & 0xFFFFFF,
-			hv_host_info_ecx, hv_host_info_edx >> 24);
-	}
-
 	if (ms_hyperv.features & HV_ACCESS_FREQUENCY_MSRS &&
 	    ms_hyperv.misc_features & HV_FEATURE_FREQUENCY_MSRS_AVAILABLE) {
 		x86_platform.calibrate_tsc = hv_get_tsc_khz;
diff --git a/drivers/hv/hv_common.c b/drivers/hv/hv_common.c
index 2f1dd4b07f9a..5d64cb0a709d 100644
--- a/drivers/hv/hv_common.c
+++ b/drivers/hv/hv_common.c
@@ -278,6 +278,14 @@ static void hv_kmsg_dump_register(void)
 int __init hv_common_init(void)
 {
 	int i;
+	union hv_hypervisor_version_info version;
+
+	/* Get information about the Hyper-V host version */
+	if (!hv_get_hypervisor_version(&version))
+		pr_info("Hyper-V: Host Build %d.%d.%d.%d-%d-%d\n",
+			version.major_version, version.minor_version,
+			version.build_number, version.service_number,
+			version.service_pack, version.service_branch);
 
 	if (hv_is_isolation_supported())
 		sysctl_record_panic_msg = 0;
diff --git a/include/asm-generic/hyperv-tlfs.h b/include/asm-generic/hyperv-tlfs.h
index 3d1b31f90ed6..32514a870b98 100644
--- a/include/asm-generic/hyperv-tlfs.h
+++ b/include/asm-generic/hyperv-tlfs.h
@@ -817,6 +817,29 @@ struct hv_input_unmap_device_interrupt {
 #define HV_SOURCE_SHADOW_NONE               0x0
 #define HV_SOURCE_SHADOW_BRIDGE_BUS_RANGE   0x1
 
+/*
+ * Version info reported by hypervisor
+ */
+union hv_hypervisor_version_info {
+	struct {
+		u32 build_number;
+
+		u32 minor_version : 16;
+		u32 major_version : 16;
+
+		u32 service_pack;
+
+		u32 service_number : 24;
+		u32 service_branch : 8;
+	};
+	struct {
+		u32 eax;
+		u32 ebx;
+		u32 ecx;
+		u32 edx;
+	};
+};
+
 /*
  * The whole argument should fit in a page to be able to pass to the hypervisor
  * in one hypercall.
diff --git a/include/asm-generic/mshyperv.h b/include/asm-generic/mshyperv.h
index 04424a446bb7..f8e7428f1e55 100644
--- a/include/asm-generic/mshyperv.h
+++ b/include/asm-generic/mshyperv.h
@@ -275,6 +275,7 @@ static inline int cpumask_to_vpset_skip(struct hv_vpset *vpset,
 	return __cpumask_to_vpset(vpset, cpus, func);
 }
 
+int hv_get_hypervisor_version(union hv_hypervisor_version_info *info);
 void hyperv_report_panic(struct pt_regs *regs, long err, bool in_die);
 bool hv_is_hyperv_initialized(void);
 bool hv_is_hibernation_supported(void);
-- 
2.25.1