Merge tag 'hyperv-next-signed-20240320' of git://git.kernel.org/pub/scm/linux/kernel/git/hyperv/linux

Pull hyperv updates from Wei Liu:

 - Use Hyper-V entropy to seed guest random number generator (Michael
   Kelley)

 - Convert to platform remove callback returning void for vmbus (Uwe
   Kleine-König)

 - Introduce hv_get_hypervisor_version function (Nuno Das Neves)

 - Rename some HV_REGISTER_* defines for consistency (Nuno Das Neves)

 - Change prefix of generic HV_REGISTER_* MSRs to HV_MSR_* (Nuno Das
   Neves)

 - Cosmetic changes for hv_spinlock.c (Purna Pavan Chandra Aekkaladevi)

 - Use per cpu initial stack for vtl context (Saurabh Sengar)

* tag 'hyperv-next-signed-20240320' of git://git.kernel.org/pub/scm/linux/kernel/git/hyperv/linux:
  x86/hyperv: Use Hyper-V entropy to seed guest random number generator
  x86/hyperv: Cosmetic changes for hv_spinlock.c
  hyperv-tlfs: Rename some HV_REGISTER_* defines for consistency
  hv: vmbus: Convert to platform remove callback returning void
  mshyperv: Introduce hv_get_hypervisor_version function
  x86/hyperv: Use per cpu initial stack for vtl context
  hyperv-tlfs: Change prefix of generic HV_REGISTER_* MSRs to HV_MSR_*

17 files changed, 375 insertions, 236 deletions

diff --git a/arch/arm64/hyperv/hv_core.c b/arch/arm64/hyperv/hv_core.c
index b54c34793701..f1ebc025e1df 100644
--- a/arch/arm64/hyperv/hv_core.c
+++ b/arch/arm64/hyperv/hv_core.c
@@ -160,22 +160,22 @@ void hyperv_report_panic(struct pt_regs *regs, long err, bool in_die)
 		return;
 	panic_reported = true;
 
-	guest_id = hv_get_vpreg(HV_REGISTER_GUEST_OSID);
+	guest_id = hv_get_vpreg(HV_REGISTER_GUEST_OS_ID);
 
 	/*
 	 * Hyper-V provides the ability to store only 5 values.
 	 * Pick the passed in error value, the guest_id, the PC,
 	 * and the SP.
 	 */
-	hv_set_vpreg(HV_REGISTER_CRASH_P0, err);
-	hv_set_vpreg(HV_REGISTER_CRASH_P1, guest_id);
-	hv_set_vpreg(HV_REGISTER_CRASH_P2, regs->pc);
-	hv_set_vpreg(HV_REGISTER_CRASH_P3, regs->sp);
-	hv_set_vpreg(HV_REGISTER_CRASH_P4, 0);
+	hv_set_vpreg(HV_REGISTER_GUEST_CRASH_P0, err);
+	hv_set_vpreg(HV_REGISTER_GUEST_CRASH_P1, guest_id);
+	hv_set_vpreg(HV_REGISTER_GUEST_CRASH_P2, regs->pc);
+	hv_set_vpreg(HV_REGISTER_GUEST_CRASH_P3, regs->sp);
+	hv_set_vpreg(HV_REGISTER_GUEST_CRASH_P4, 0);
 
 	/*
 	 * Let Hyper-V know there is crash data available
 	 */
-	hv_set_vpreg(HV_REGISTER_CRASH_CTL, HV_CRASH_CTL_CRASH_NOTIFY);
+	hv_set_vpreg(HV_REGISTER_GUEST_CRASH_CTL, HV_CRASH_CTL_CRASH_NOTIFY);
 }
 EXPORT_SYMBOL_GPL(hyperv_report_panic);
diff --git a/arch/arm64/hyperv/mshyperv.c b/arch/arm64/hyperv/mshyperv.c
index f1b8a04ee9f2..b1a4de4eee29 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;
 
@@ -39,7 +46,7 @@ static int __init hyperv_init(void)
 
 	/* Setup the guest ID */
 	guest_id = hv_generate_guest_id(LINUX_VERSION_CODE);
-	hv_set_vpreg(HV_REGISTER_GUEST_OSID, guest_id);
+	hv_set_vpreg(HV_REGISTER_GUEST_OS_ID, guest_id);
 
 	/* Get the features and hints from Hyper-V */
 	hv_get_vpreg_128(HV_REGISTER_FEATURES, &result);
@@ -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;
@@ -74,6 +72,8 @@ static int __init hyperv_init(void)
 		return ret;
 	}
 
+	ms_hyperv_late_init();
+
 	hyperv_initialized = true;
 	return 0;
 }
diff --git a/arch/arm64/include/asm/hyperv-tlfs.h b/arch/arm64/include/asm/hyperv-tlfs.h
index bc6c7ac934a1..bc30aadedfe9 100644
--- a/arch/arm64/include/asm/hyperv-tlfs.h
+++ b/arch/arm64/include/asm/hyperv-tlfs.h
@@ -22,14 +22,6 @@
  */
 
 /*
- * These Hyper-V registers provide information equivalent to the CPUID
- * instruction on x86/x64.
- */
-#define HV_REGISTER_HYPERVISOR_VERSION		0x00000100 /*CPUID 0x40000002 */
-#define HV_REGISTER_FEATURES			0x00000200 /*CPUID 0x40000003 */
-#define HV_REGISTER_ENLIGHTENMENTS		0x00000201 /*CPUID 0x40000004 */
-
-/*
  * Group C Features. See the asm-generic version of hyperv-tlfs.h
  * for a description of Feature Groups.
  */
@@ -41,28 +33,29 @@
 #define HV_STIMER_DIRECT_MODE_AVAILABLE		BIT(13)
 
 /*
- * Synthetic register definitions equivalent to MSRs on x86/x64
+ * To support arch-generic code calling hv_set/get_register:
+ * - On x86, HV_MSR_ indicates an MSR accessed via rdmsrl/wrmsrl
+ * - On ARM, HV_MSR_ indicates a VP register accessed via hypercall
  */
-#define HV_REGISTER_CRASH_P0		0x00000210
-#define HV_REGISTER_CRASH_P1		0x00000211
-#define HV_REGISTER_CRASH_P2		0x00000212
-#define HV_REGISTER_CRASH_P3		0x00000213
-#define HV_REGISTER_CRASH_P4		0x00000214
-#define HV_REGISTER_CRASH_CTL		0x00000215
+#define HV_MSR_CRASH_P0		(HV_REGISTER_GUEST_CRASH_P0)
+#define HV_MSR_CRASH_P1		(HV_REGISTER_GUEST_CRASH_P1)
+#define HV_MSR_CRASH_P2		(HV_REGISTER_GUEST_CRASH_P2)
+#define HV_MSR_CRASH_P3		(HV_REGISTER_GUEST_CRASH_P3)
+#define HV_MSR_CRASH_P4		(HV_REGISTER_GUEST_CRASH_P4)
+#define HV_MSR_CRASH_CTL	(HV_REGISTER_GUEST_CRASH_CTL)
 
-#define HV_REGISTER_GUEST_OSID		0x00090002
-#define HV_REGISTER_VP_INDEX		0x00090003
-#define HV_REGISTER_TIME_REF_COUNT	0x00090004
-#define HV_REGISTER_REFERENCE_TSC	0x00090017
+#define HV_MSR_VP_INDEX		(HV_REGISTER_VP_INDEX)
+#define HV_MSR_TIME_REF_COUNT	(HV_REGISTER_TIME_REF_COUNT)
+#define HV_MSR_REFERENCE_TSC	(HV_REGISTER_REFERENCE_TSC)
 
-#define HV_REGISTER_SINT0		0x000A0000
-#define HV_REGISTER_SCONTROL		0x000A0010
-#define HV_REGISTER_SIEFP		0x000A0012
-#define HV_REGISTER_SIMP		0x000A0013
-#define HV_REGISTER_EOM			0x000A0014
+#define HV_MSR_SINT0		(HV_REGISTER_SINT0)
+#define HV_MSR_SCONTROL		(HV_REGISTER_SCONTROL)
+#define HV_MSR_SIEFP		(HV_REGISTER_SIEFP)
+#define HV_MSR_SIMP		(HV_REGISTER_SIMP)
+#define HV_MSR_EOM		(HV_REGISTER_EOM)
 
-#define HV_REGISTER_STIMER0_CONFIG	0x000B0000
-#define HV_REGISTER_STIMER0_COUNT	0x000B0001
+#define HV_MSR_STIMER0_CONFIG	(HV_REGISTER_STIMER0_CONFIG)
+#define HV_MSR_STIMER0_COUNT	(HV_REGISTER_STIMER0_COUNT)
 
 union hv_msi_entry {
 	u64 as_uint64[2];
diff --git a/arch/arm64/include/asm/mshyperv.h b/arch/arm64/include/asm/mshyperv.h
index 20070a847304..a975e1a689dd 100644
--- a/arch/arm64/include/asm/mshyperv.h
+++ b/arch/arm64/include/asm/mshyperv.h
@@ -31,12 +31,12 @@ void hv_set_vpreg(u32 reg, u64 value);
 u64 hv_get_vpreg(u32 reg);
 void hv_get_vpreg_128(u32 reg, struct hv_get_vp_registers_output *result);
 
-static inline void hv_set_register(unsigned int reg, u64 value)
+static inline void hv_set_msr(unsigned int reg, u64 value)
 {
 	hv_set_vpreg(reg, value);
 }
 
-static inline u64 hv_get_register(unsigned int reg)
+static inline u64 hv_get_msr(unsigned int reg)
 {
 	return hv_get_vpreg(reg);
 }
diff --git a/arch/x86/hyperv/hv_init.c b/arch/x86/hyperv/hv_init.c
index 8f3a4d16bb79..17a71e92a343 100644
--- a/arch/x86/hyperv/hv_init.c
+++ b/arch/x86/hyperv/hv_init.c
@@ -667,14 +667,14 @@ void hyperv_cleanup(void)
 	hv_hypercall_pg = NULL;
 
 	/* Reset the hypercall page */
-	hypercall_msr.as_uint64 = hv_get_register(HV_X64_MSR_HYPERCALL);
+	hypercall_msr.as_uint64 = hv_get_msr(HV_X64_MSR_HYPERCALL);
 	hypercall_msr.enable = 0;
-	hv_set_register(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64);
+	hv_set_msr(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64);
 
 	/* Reset the TSC page */
-	tsc_msr.as_uint64 = hv_get_register(HV_X64_MSR_REFERENCE_TSC);
+	tsc_msr.as_uint64 = hv_get_msr(HV_X64_MSR_REFERENCE_TSC);
 	tsc_msr.enable = 0;
-	hv_set_register(HV_X64_MSR_REFERENCE_TSC, tsc_msr.as_uint64);
+	hv_set_msr(HV_X64_MSR_REFERENCE_TSC, tsc_msr.as_uint64);
 }
 
 void hyperv_report_panic(struct pt_regs *regs, long err, bool in_die)
diff --git a/arch/x86/hyperv/hv_spinlock.c b/arch/x86/hyperv/hv_spinlock.c
index 737d6f7a6155..151e851bef09 100644
--- a/arch/x86/hyperv/hv_spinlock.c
+++ b/arch/x86/hyperv/hv_spinlock.c
@@ -16,7 +16,7 @@
 #include <asm/paravirt.h>
 #include <asm/apic.h>
 
-static bool __initdata hv_pvspin = true;
+static bool hv_pvspin __initdata = true;
 
 static void hv_qlock_kick(int cpu)
 {
@@ -64,6 +64,7 @@ __visible bool hv_vcpu_is_preempted(int vcpu)
 {
 	return false;
 }
+
 PV_CALLEE_SAVE_REGS_THUNK(hv_vcpu_is_preempted);
 
 void __init hv_init_spinlocks(void)
diff --git a/arch/x86/hyperv/hv_vtl.c b/arch/x86/hyperv/hv_vtl.c
index edd2f35b2a5e..5c7de79423b8 100644
--- a/arch/x86/hyperv/hv_vtl.c
+++ b/arch/x86/hyperv/hv_vtl.c
@@ -12,6 +12,7 @@
 #include <asm/i8259.h>
 #include <asm/mshyperv.h>
 #include <asm/realmode.h>
+#include <../kernel/smpboot.h>
 
 extern struct boot_params boot_params;
 static struct real_mode_header hv_vtl_real_mode_header;
@@ -65,7 +66,7 @@ static void hv_vtl_ap_entry(void)
 	((secondary_startup_64_fn)secondary_startup_64)(&boot_params, &boot_params);
 }
 
-static int hv_vtl_bringup_vcpu(u32 target_vp_index, u64 eip_ignored)
+static int hv_vtl_bringup_vcpu(u32 target_vp_index, int cpu, u64 eip_ignored)
 {
 	u64 status;
 	int ret = 0;
@@ -79,7 +80,9 @@ static int hv_vtl_bringup_vcpu(u32 target_vp_index, u64 eip_ignored)
 	struct ldttss_desc *ldt;
 	struct desc_struct *gdt;
 
-	u64 rsp = current->thread.sp;
+	struct task_struct *idle = idle_thread_get(cpu);
+	u64 rsp = (unsigned long)idle->thread.sp;
+
 	u64 rip = (u64)&hv_vtl_ap_entry;
 
 	native_store_gdt(&gdt_ptr);
@@ -206,7 +209,15 @@ static int hv_vtl_apicid_to_vp_id(u32 apic_id)
 
 static int hv_vtl_wakeup_secondary_cpu(u32 apicid, unsigned long start_eip)
 {
-	int vp_id;
+	int vp_id, cpu;
+
+	/* Find the logical CPU for the APIC ID */
+	for_each_present_cpu(cpu) {
+		if (arch_match_cpu_phys_id(cpu, apicid))
+			break;
+	}
+	if (cpu >= nr_cpu_ids)
+		return -EINVAL;
 
 	pr_debug("Bringing up CPU with APIC ID %d in VTL2...\n", apicid);
 	vp_id = hv_vtl_apicid_to_vp_id(apicid);
@@ -220,7 +231,7 @@ static int hv_vtl_wakeup_secondary_cpu(u32 apicid, unsigned long start_eip)
 		return -EINVAL;
 	}
 
-	return hv_vtl_bringup_vcpu(vp_id, start_eip);
+	return hv_vtl_bringup_vcpu(vp_id, cpu, start_eip);
 }
 
 int __init hv_vtl_early_init(void)
diff --git a/arch/x86/include/asm/hyperv-tlfs.h b/arch/x86/include/asm/hyperv-tlfs.h
index 2ff26f53cd62..3787d26810c1 100644
--- a/arch/x86/include/asm/hyperv-tlfs.h
+++ b/arch/x86/include/asm/hyperv-tlfs.h
@@ -182,7 +182,7 @@ enum hv_isolation_type {
 #define HV_X64_MSR_HYPERCALL			0x40000001
 
 /* MSR used to provide vcpu index */
-#define HV_REGISTER_VP_INDEX			0x40000002
+#define HV_X64_MSR_VP_INDEX			0x40000002
 
 /* MSR used to reset the guest OS. */
 #define HV_X64_MSR_RESET			0x40000003
@@ -191,10 +191,10 @@ enum hv_isolation_type {
 #define HV_X64_MSR_VP_RUNTIME			0x40000010
 
 /* MSR used to read the per-partition time reference counter */
-#define HV_REGISTER_TIME_REF_COUNT		0x40000020
+#define HV_X64_MSR_TIME_REF_COUNT		0x40000020
 
 /* A partition's reference time stamp counter (TSC) page */
-#define HV_REGISTER_REFERENCE_TSC		0x40000021
+#define HV_X64_MSR_REFERENCE_TSC		0x40000021
 
 /* MSR used to retrieve the TSC frequency */
 #define HV_X64_MSR_TSC_FREQUENCY		0x40000022
@@ -209,61 +209,61 @@ enum hv_isolation_type {
 #define HV_X64_MSR_VP_ASSIST_PAGE		0x40000073
 
 /* Define synthetic interrupt controller model specific registers. */
-#define HV_REGISTER_SCONTROL			0x40000080
-#define HV_REGISTER_SVERSION			0x40000081
-#define HV_REGISTER_SIEFP			0x40000082
-#define HV_REGISTER_SIMP			0x40000083
-#define HV_REGISTER_EOM				0x40000084
-#define HV_REGISTER_SINT0			0x40000090
-#define HV_REGISTER_SINT1			0x40000091
-#define HV_REGISTER_SINT2			0x40000092
-#define HV_REGISTER_SINT3			0x40000093
-#define HV_REGISTER_SINT4			0x40000094
-#define HV_REGISTER_SINT5			0x40000095
-#define HV_REGISTER_SINT6			0x40000096
-#define HV_REGISTER_SINT7			0x40000097
-#define HV_REGISTER_SINT8			0x40000098
-#define HV_REGISTER_SINT9			0x40000099
-#define HV_REGISTER_SINT10			0x4000009A
-#define HV_REGISTER_SINT11			0x4000009B
-#define HV_REGISTER_SINT12			0x4000009C
-#define HV_REGISTER_SINT13			0x4000009D
-#define HV_REGISTER_SINT14			0x4000009E
-#define HV_REGISTER_SINT15			0x4000009F
+#define HV_X64_MSR_SCONTROL			0x40000080
+#define HV_X64_MSR_SVERSION			0x40000081
+#define HV_X64_MSR_SIEFP			0x40000082
+#define HV_X64_MSR_SIMP				0x40000083
+#define HV_X64_MSR_EOM				0x40000084
+#define HV_X64_MSR_SINT0			0x40000090
+#define HV_X64_MSR_SINT1			0x40000091
+#define HV_X64_MSR_SINT2			0x40000092
+#define HV_X64_MSR_SINT3			0x40000093
+#define HV_X64_MSR_SINT4			0x40000094
+#define HV_X64_MSR_SINT5			0x40000095
+#define HV_X64_MSR_SINT6			0x40000096
+#define HV_X64_MSR_SINT7			0x40000097
+#define HV_X64_MSR_SINT8			0x40000098
+#define HV_X64_MSR_SINT9			0x40000099
+#define HV_X64_MSR_SINT10			0x4000009A
+#define HV_X64_MSR_SINT11			0x4000009B
+#define HV_X64_MSR_SINT12			0x4000009C
+#define HV_X64_MSR_SINT13			0x4000009D
+#define HV_X64_MSR_SINT14			0x4000009E
+#define HV_X64_MSR_SINT15			0x4000009F
 
 /*
  * Define synthetic interrupt controller model specific registers for
  * nested hypervisor.
  */
-#define HV_REGISTER_NESTED_SCONTROL            0x40001080
-#define HV_REGISTER_NESTED_SVERSION            0x40001081
-#define HV_REGISTER_NESTED_SIEFP               0x40001082
-#define HV_REGISTER_NESTED_SIMP                0x40001083
-#define HV_REGISTER_NESTED_EOM                 0x40001084
-#define HV_REGISTER_NESTED_SINT0               0x40001090
+#define HV_X64_MSR_NESTED_SCONTROL		0x40001080
+#define HV_X64_MSR_NESTED_SVERSION		0x40001081
+#define HV_X64_MSR_NESTED_SIEFP			0x40001082
+#define HV_X64_MSR_NESTED_SIMP			0x40001083
+#define HV_X64_MSR_NESTED_EOM			0x40001084
+#define HV_X64_MSR_NESTED_SINT0			0x40001090
 
 /*
  * Synthetic Timer MSRs. Four timers per vcpu.
  */
-#define HV_REGISTER_STIMER0_CONFIG		0x400000B0
-#define HV_REGISTER_STIMER0_COUNT		0x400000B1
-#define HV_REGISTER_STIMER1_CONFIG		0x400000B2
-#define HV_REGISTER_STIMER1_COUNT		0x400000B3
-#define HV_REGISTER_STIMER2_CONFIG		0x400000B4
-#define HV_REGISTER_STIMER2_COUNT		0x400000B5
-#define HV_REGISTER_STIMER3_CONFIG		0x400000B6
-#define HV_REGISTER_STIMER3_COUNT		0x400000B7
+#define HV_X64_MSR_STIMER0_CONFIG		0x400000B0
+#define HV_X64_MSR_STIMER0_COUNT		0x400000B1
+#define HV_X64_MSR_STIMER1_CONFIG		0x400000B2
+#define HV_X64_MSR_STIMER1_COUNT		0x400000B3
+#define HV_X64_MSR_STIMER2_CONFIG		0x400000B4
+#define HV_X64_MSR_STIMER2_COUNT		0x400000B5
+#define HV_X64_MSR_STIMER3_CONFIG		0x400000B6
+#define HV_X64_MSR_STIMER3_COUNT		0x400000B7
 
 /* Hyper-V guest idle MSR */
 #define HV_X64_MSR_GUEST_IDLE			0x400000F0
 
 /* Hyper-V guest crash notification MSR's */
-#define HV_REGISTER_CRASH_P0			0x40000100
-#define HV_REGISTER_CRASH_P1			0x40000101
-#define HV_REGISTER_CRASH_P2			0x40000102
-#define HV_REGISTER_CRASH_P3			0x40000103
-#define HV_REGISTER_CRASH_P4			0x40000104
-#define HV_REGISTER_CRASH_CTL			0x40000105
+#define HV_X64_MSR_CRASH_P0			0x40000100
+#define HV_X64_MSR_CRASH_P1			0x40000101
+#define HV_X64_MSR_CRASH_P2			0x40000102
+#define HV_X64_MSR_CRASH_P3			0x40000103
+#define HV_X64_MSR_CRASH_P4			0x40000104
+#define HV_X64_MSR_CRASH_CTL			0x40000105
 
 /* TSC emulation after migration */
 #define HV_X64_MSR_REENLIGHTENMENT_CONTROL	0x40000106
@@ -276,31 +276,38 @@ enum hv_isolation_type {
 /* HV_X64_MSR_TSC_INVARIANT_CONTROL bits */
 #define HV_EXPOSE_INVARIANT_TSC		BIT_ULL(0)
 
-/* Register name aliases for temporary compatibility */
-#define HV_X64_MSR_STIMER0_COUNT	HV_REGISTER_STIMER0_COUNT
-#define HV_X64_MSR_STIMER0_CONFIG	HV_REGISTER_STIMER0_CONFIG
-#define HV_X64_MSR_STIMER1_COUNT	HV_REGISTER_STIMER1_COUNT
-#define HV_X64_MSR_STIMER1_CONFIG	HV_REGISTER_STIMER1_CONFIG
-#define HV_X64_MSR_STIMER2_COUNT	HV_REGISTER_STIMER2_COUNT
-#define HV_X64_MSR_STIMER2_CONFIG	HV_REGISTER_STIMER2_CONFIG
-#define HV_X64_MSR_STIMER3_COUNT	HV_REGISTER_STIMER3_COUNT
-#define HV_X64_MSR_STIMER3_CONFIG	HV_REGISTER_STIMER3_CONFIG
-#define HV_X64_MSR_SCONTROL		HV_REGISTER_SCONTROL
-#define HV_X64_MSR_SVERSION		HV_REGISTER_SVERSION
-#define HV_X64_MSR_SIMP			HV_REGISTER_SIMP
-#define HV_X64_MSR_SIEFP		HV_REGISTER_SIEFP
-#define HV_X64_MSR_VP_INDEX		HV_REGISTER_VP_INDEX
-#define HV_X64_MSR_EOM			HV_REGISTER_EOM
-#define HV_X64_MSR_SINT0		HV_REGISTER_SINT0
-#define HV_X64_MSR_SINT15		HV_REGISTER_SINT15
-#define HV_X64_MSR_CRASH_P0		HV_REGISTER_CRASH_P0
-#define HV_X64_MSR_CRASH_P1		HV_REGISTER_CRASH_P1
-#define HV_X64_MSR_CRASH_P2		HV_REGISTER_CRASH_P2
-#define HV_X64_MSR_CRASH_P3		HV_REGISTER_CRASH_P3
-#define HV_X64_MSR_CRASH_P4		HV_REGISTER_CRASH_P4
-#define HV_X64_MSR_CRASH_CTL		HV_REGISTER_CRASH_CTL
-#define HV_X64_MSR_TIME_REF_COUNT	HV_REGISTER_TIME_REF_COUNT
-#define HV_X64_MSR_REFERENCE_TSC	HV_REGISTER_REFERENCE_TSC
+/*
+ * To support arch-generic code calling hv_set/get_register:
+ * - On x86, HV_MSR_ indicates an MSR accessed via rdmsrl/wrmsrl
+ * - On ARM, HV_MSR_ indicates a VP register accessed via hypercall
+ */
+#define HV_MSR_CRASH_P0		(HV_X64_MSR_CRASH_P0)
+#define HV_MSR_CRASH_P1		(HV_X64_MSR_CRASH_P1)
+#define HV_MSR_CRASH_P2		(HV_X64_MSR_CRASH_P2)
+#define HV_MSR_CRASH_P3		(HV_X64_MSR_CRASH_P3)
+#define HV_MSR_CRASH_P4		(HV_X64_MSR_CRASH_P4)
+#define HV_MSR_CRASH_CTL	(HV_X64_MSR_CRASH_CTL)
+
+#define HV_MSR_VP_INDEX		(HV_X64_MSR_VP_INDEX)
+#define HV_MSR_TIME_REF_COUNT	(HV_X64_MSR_TIME_REF_COUNT)
+#define HV_MSR_REFERENCE_TSC	(HV_X64_MSR_REFERENCE_TSC)
+
+#define HV_MSR_SINT0		(HV_X64_MSR_SINT0)
+#define HV_MSR_SVERSION		(HV_X64_MSR_SVERSION)
+#define HV_MSR_SCONTROL		(HV_X64_MSR_SCONTROL)
+#define HV_MSR_SIEFP		(HV_X64_MSR_SIEFP)
+#define HV_MSR_SIMP		(HV_X64_MSR_SIMP)
+#define HV_MSR_EOM		(HV_X64_MSR_EOM)
+
+#define HV_MSR_NESTED_SCONTROL	(HV_X64_MSR_NESTED_SCONTROL)
+#define HV_MSR_NESTED_SVERSION	(HV_X64_MSR_NESTED_SVERSION)
+#define HV_MSR_NESTED_SIEFP	(HV_X64_MSR_NESTED_SIEFP)
+#define HV_MSR_NESTED_SIMP	(HV_X64_MSR_NESTED_SIMP)
+#define HV_MSR_NESTED_EOM	(HV_X64_MSR_NESTED_EOM)
+#define HV_MSR_NESTED_SINT0	(HV_X64_MSR_NESTED_SINT0)
+
+#define HV_MSR_STIMER0_CONFIG	(HV_X64_MSR_STIMER0_CONFIG)
+#define HV_MSR_STIMER0_COUNT	(HV_X64_MSR_STIMER0_COUNT)
 
 /*
  * Registers are only accessible via HVCALL_GET_VP_REGISTERS hvcall and
diff --git a/arch/x86/include/asm/mshyperv.h b/arch/x86/include/asm/mshyperv.h
index ce4ce8720d55..390c4d13956d 100644
--- a/arch/x86/include/asm/mshyperv.h
+++ b/arch/x86/include/asm/mshyperv.h
@@ -293,24 +293,24 @@ static inline void hv_ivm_msr_write(u64 msr, u64 value) {}
 static inline void hv_ivm_msr_read(u64 msr, u64 *value) {}
 #endif
 
-static inline bool hv_is_synic_reg(unsigned int reg)
+static inline bool hv_is_synic_msr(unsigned int reg)
 {
-	return (reg >= HV_REGISTER_SCONTROL) &&
-	       (reg <= HV_REGISTER_SINT15);
+	return (reg >= HV_X64_MSR_SCONTROL) &&
+	       (reg <= HV_X64_MSR_SINT15);
 }
 
-static inline bool hv_is_sint_reg(unsigned int reg)
+static inline bool hv_is_sint_msr(unsigned int reg)
 {
-	return (reg >= HV_REGISTER_SINT0) &&
-	       (reg <= HV_REGISTER_SINT15);
+	return (reg >= HV_X64_MSR_SINT0) &&
+	       (reg <= HV_X64_MSR_SINT15);
 }
 
-u64 hv_get_register(unsigned int reg);
-void hv_set_register(unsigned int reg, u64 value);
-u64 hv_get_non_nested_register(unsigned int reg);
-void hv_set_non_nested_register(unsigned int reg, u64 value);
+u64 hv_get_msr(unsigned int reg);
+void hv_set_msr(unsigned int reg, u64 value);
+u64 hv_get_non_nested_msr(unsigned int reg);
+void hv_set_non_nested_msr(unsigned int reg, u64 value);
 
-static __always_inline u64 hv_raw_get_register(unsigned int reg)
+static __always_inline u64 hv_raw_get_msr(unsigned int reg)
 {
 	return __rdmsr(reg);
 }
@@ -331,10 +331,10 @@ static inline int hyperv_flush_guest_mapping_range(u64 as,
 {
 	return -1;
 }
-static inline void hv_set_register(unsigned int reg, u64 value) { }
-static inline u64 hv_get_register(unsigned int reg) { return 0; }
-static inline void hv_set_non_nested_register(unsigned int reg, u64 value) { }
-static inline u64 hv_get_non_nested_register(unsigned int reg) { return 0; }
+static inline void hv_set_msr(unsigned int reg, u64 value) { }
+static inline u64 hv_get_msr(unsigned int reg) { return 0; }
+static inline void hv_set_non_nested_msr(unsigned int reg, u64 value) { }
+static inline u64 hv_get_non_nested_msr(unsigned int reg) { return 0; }
 #endif /* CONFIG_HYPERV */
 
 
diff --git a/arch/x86/kernel/cpu/mshyperv.c b/arch/x86/kernel/cpu/mshyperv.c
index 303fef824167..e0fd57a8ba84 100644
--- a/arch/x86/kernel/cpu/mshyperv.c
+++ b/arch/x86/kernel/cpu/mshyperv.c
@@ -45,70 +45,70 @@ bool hyperv_paravisor_present __ro_after_init;
 EXPORT_SYMBOL_GPL(hyperv_paravisor_present);
 
 #if IS_ENABLED(CONFIG_HYPERV)
-static inline unsigned int hv_get_nested_reg(unsigned int reg)
+static inline unsigned int hv_get_nested_msr(unsigned int reg)
 {
-	if (hv_is_sint_reg(reg))
-		return reg - HV_REGISTER_SINT0 + HV_REGISTER_NESTED_SINT0;
+	if (hv_is_sint_msr(reg))
+		return reg - HV_X64_MSR_SINT0 + HV_X64_MSR_NESTED_SINT0;
 
 	switch (reg) {
-	case HV_REGISTER_SIMP:
-		return HV_REGISTER_NESTED_SIMP;
-	case HV_REGISTER_SIEFP:
-		return HV_REGISTER_NESTED_SIEFP;
-	case HV_REGISTER_SVERSION:
-		return HV_REGISTER_NESTED_SVERSION;
-	case HV_REGISTER_SCONTROL:
-		return HV_REGISTER_NESTED_SCONTROL;
-	case HV_REGISTER_EOM:
-		return HV_REGISTER_NESTED_EOM;
+	case HV_X64_MSR_SIMP:
+		return HV_X64_MSR_NESTED_SIMP;
+	case HV_X64_MSR_SIEFP:
+		return HV_X64_MSR_NESTED_SIEFP;
+	case HV_X64_MSR_SVERSION:
+		return HV_X64_MSR_NESTED_SVERSION;
+	case HV_X64_MSR_SCONTROL:
+		return HV_X64_MSR_NESTED_SCONTROL;
+	case HV_X64_MSR_EOM:
+		return HV_X64_MSR_NESTED_EOM;
 	default:
 		return reg;
 	}
 }
 
-u64 hv_get_non_nested_register(unsigned int reg)
+u64 hv_get_non_nested_msr(unsigned int reg)
 {
 	u64 value;
 
-	if (hv_is_synic_reg(reg) && ms_hyperv.paravisor_present)
+	if (hv_is_synic_msr(reg) && ms_hyperv.paravisor_present)
 		hv_ivm_msr_read(reg, &value);
 	else
 		rdmsrl(reg, value);
 	return value;
 }
-EXPORT_SYMBOL_GPL(hv_get_non_nested_register);
+EXPORT_SYMBOL_GPL(hv_get_non_nested_msr);
 
-void hv_set_non_nested_register(unsigned int reg, u64 value)
+void hv_set_non_nested_msr(unsigned int reg, u64 value)
 {
-	if (hv_is_synic_reg(reg) && ms_hyperv.paravisor_present) {
+	if (hv_is_synic_msr(reg) && ms_hyperv.paravisor_present) {
 		hv_ivm_msr_write(reg, value);
 
 		/* Write proxy bit via wrmsl instruction */
-		if (hv_is_sint_reg(reg))
+		if (hv_is_sint_msr(reg))
 			wrmsrl(reg, value | 1 << 20);
 	} else {
 		wrmsrl(reg, value);
 	}
 }
-EXPORT_SYMBOL_GPL(hv_set_non_nested_register);
+EXPORT_SYMBOL_GPL(hv_set_non_nested_msr);
 
-u64 hv_get_register(unsigned int reg)
+u64 hv_get_msr(unsigned int reg)
 {
 	if (hv_nested)
-		reg = hv_get_nested_reg(reg);
+		reg = hv_get_nested_msr(reg);
 
-	return hv_get_non_nested_register(reg);
+	return hv_get_non_nested_msr(reg);
 }
-EXPORT_SYMBOL_GPL(hv_get_register);
+EXPORT_SYMBOL_GPL(hv_get_msr);
 
-void hv_set_register(unsigned int reg, u64 value)
+void hv_set_msr(unsigned int reg, u64 value)
 {
 	if (hv_nested)
-		reg = hv_get_nested_reg(reg);
+		reg = hv_get_nested_msr(reg);
 
-	hv_set_non_nested_register(reg, value);
+	hv_set_non_nested_msr(reg, value);
 }
-EXPORT_SYMBOL_GPL(hv_set_register);
+EXPORT_SYMBOL_GPL(hv_set_msr);
 
 static void (*vmbus_handler)(void);
 static void (*hv_stimer0_handler)(void);
@@ -352,13 +352,24 @@ 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";
@@ -409,21 +420,6 @@ 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;
@@ -456,7 +452,7 @@ static void __init ms_hyperv_init_platform(void)
 				/* To be supported: more work is required.  */
 				ms_hyperv.features &= ~HV_MSR_REFERENCE_TSC_AVAILABLE;
 
-				/* HV_REGISTER_CRASH_CTL is unsupported. */
+				/* HV_MSR_CRASH_CTL is unsupported. */
 				ms_hyperv.misc_features &= ~HV_FEATURE_GUEST_CRASH_MSR_AVAILABLE;
 
 				/* Don't trust Hyper-V's TLB-flushing hypercalls. */
@@ -648,6 +644,7 @@ const __initconst struct hypervisor_x86 x86_hyper_ms_hyperv = {
 	.init.x2apic_available	= ms_hyperv_x2apic_available,
 	.init.msi_ext_dest_id	= ms_hyperv_msi_ext_dest_id,
 	.init.init_platform	= ms_hyperv_init_platform,
+	.init.guest_late_init	= ms_hyperv_late_init,
 #ifdef CONFIG_AMD_MEM_ENCRYPT
 	.runtime.sev_es_hcall_prepare = hv_sev_es_hcall_prepare,
 	.runtime.sev_es_hcall_finish = hv_sev_es_hcall_finish,
diff --git a/drivers/clocksource/hyperv_timer.c b/drivers/clocksource/hyperv_timer.c
index 8ff7cd4e20bb..b2a080647e41 100644
--- a/drivers/clocksource/hyperv_timer.c
+++ b/drivers/clocksource/hyperv_timer.c
@@ -81,14 +81,14 @@ static int hv_ce_set_next_event(unsigned long delta,
 
 	current_tick = hv_read_reference_counter();
 	current_tick += delta;
-	hv_set_register(HV_REGISTER_STIMER0_COUNT, current_tick);
+	hv_set_msr(HV_MSR_STIMER0_COUNT, current_tick);
 	return 0;
 }
 
 static int hv_ce_shutdown(struct clock_event_device *evt)
 {
-	hv_set_register(HV_REGISTER_STIMER0_COUNT, 0);
-	hv_set_register(HV_REGISTER_STIMER0_CONFIG, 0);
+	hv_set_msr(HV_MSR_STIMER0_COUNT, 0);
+	hv_set_msr(HV_MSR_STIMER0_CONFIG, 0);
 	if (direct_mode_enabled && stimer0_irq >= 0)
 		disable_percpu_irq(stimer0_irq);
 
@@ -119,7 +119,7 @@ static int hv_ce_set_oneshot(struct clock_event_device *evt)
 		timer_cfg.direct_mode = 0;
 		timer_cfg.sintx = stimer0_message_sint;
 	}
-	hv_set_register(HV_REGISTER_STIMER0_CONFIG, timer_cfg.as_uint64);
+	hv_set_msr(HV_MSR_STIMER0_CONFIG, timer_cfg.as_uint64);
 	return 0;
 }
 
@@ -372,11 +372,11 @@ static __always_inline u64 read_hv_clock_msr(void)
 	 * is set to 0 when the partition is created and is incremented in 100
 	 * nanosecond units.
 	 *
-	 * Use hv_raw_get_register() because this function is used from
-	 * noinstr. Notable; while HV_REGISTER_TIME_REF_COUNT is a synthetic
+	 * Use hv_raw_get_msr() because this function is used from
+	 * noinstr. Notable; while HV_MSR_TIME_REF_COUNT is a synthetic
 	 * register it doesn't need the GHCB path.
 	 */
-	return hv_raw_get_register(HV_REGISTER_TIME_REF_COUNT);
+	return hv_raw_get_msr(HV_MSR_TIME_REF_COUNT);
 }
 
 /*
@@ -439,9 +439,9 @@ static void suspend_hv_clock_tsc(struct clocksource *arg)
 	union hv_reference_tsc_msr tsc_msr;
 
 	/* Disable the TSC page */
-	tsc_msr.as_uint64 = hv_get_register(HV_REGISTER_REFERENCE_TSC);
+	tsc_msr.as_uint64 = hv_get_msr(HV_MSR_REFERENCE_TSC);
 	tsc_msr.enable = 0;
-	hv_set_register(HV_REGISTER_REFERENCE_TSC, tsc_msr.as_uint64);
+	hv_set_msr(HV_MSR_REFERENCE_TSC, tsc_msr.as_uint64);
 }
 
 
@@ -450,10 +450,10 @@ static void resume_hv_clock_tsc(struct clocksource *arg)
 	union hv_reference_tsc_msr tsc_msr;
 
 	/* Re-enable the TSC page */
-	tsc_msr.as_uint64 = hv_get_register(HV_REGISTER_REFERENCE_TSC);
+	tsc_msr.as_uint64 = hv_get_msr(HV_MSR_REFERENCE_TSC);
 	tsc_msr.enable = 1;
 	tsc_msr.pfn = tsc_pfn;
-	hv_set_register(HV_REGISTER_REFERENCE_TSC, tsc_msr.as_uint64);
+	hv_set_msr(HV_MSR_REFERENCE_TSC, tsc_msr.as_uint64);
 }
 
 #ifdef HAVE_VDSO_CLOCKMODE_HVCLOCK
@@ -555,14 +555,14 @@ static void __init hv_init_tsc_clocksource(void)
 	 * thus TSC clocksource will work even without the real TSC page
 	 * mapped.
 	 */
-	tsc_msr.as_uint64 = hv_get_register(HV_REGISTER_REFERENCE_TSC);
+	tsc_msr.as_uint64 = hv_get_msr(HV_MSR_REFERENCE_TSC);
 	if (hv_root_partition)
 		tsc_pfn = tsc_msr.pfn;
 	else
 		tsc_pfn = HVPFN_DOWN(virt_to_phys(tsc_page));
 	tsc_msr.enable = 1;
 	tsc_msr.pfn = tsc_pfn;
-	hv_set_register(HV_REGISTER_REFERENCE_TSC, tsc_msr.as_uint64);
+	hv_set_msr(HV_MSR_REFERENCE_TSC, tsc_msr.as_uint64);
 
 	clocksource_register_hz(&hyperv_cs_tsc, NSEC_PER_SEC/100);
 
diff --git a/drivers/hv/Kconfig b/drivers/hv/Kconfig
index 00242107d62e..862c47b191af 100644
--- a/drivers/hv/Kconfig
+++ b/drivers/hv/Kconfig
@@ -16,6 +16,7 @@ config HYPERV
 config HYPERV_VTL_MODE
 	bool "Enable Linux to boot in VTL context"
 	depends on X86_64 && HYPERV
+	depends on SMP
 	default n
 	help
 	  Virtual Secure Mode (VSM) is a set of hypervisor capabilities and
diff --git a/drivers/hv/hv.c b/drivers/hv/hv.c
index 51e5018ac9b2..a8ad728354cb 100644
--- a/drivers/hv/hv.c
+++ b/drivers/hv/hv.c
@@ -270,7 +270,7 @@ void hv_synic_enable_regs(unsigned int cpu)
 	union hv_synic_scontrol sctrl;
 
 	/* Setup the Synic's message page */
-	simp.as_uint64 = hv_get_register(HV_REGISTER_SIMP);
+	simp.as_uint64 = hv_get_msr(HV_MSR_SIMP);
 	simp.simp_enabled = 1;
 
 	if (ms_hyperv.paravisor_present || hv_root_partition) {
@@ -286,10 +286,10 @@ void hv_synic_enable_regs(unsigned int cpu)
 			>> HV_HYP_PAGE_SHIFT;
 	}
 
-	hv_set_register(HV_REGISTER_SIMP, simp.as_uint64);
+	hv_set_msr(HV_MSR_SIMP, simp.as_uint64);
 
 	/* Setup the Synic's event page */
-	siefp.as_uint64 = hv_get_register(HV_REGISTER_SIEFP);
+	siefp.as_uint64 = hv_get_msr(HV_MSR_SIEFP);
 	siefp.siefp_enabled = 1;
 
 	if (ms_hyperv.paravisor_present || hv_root_partition) {
@@ -305,13 +305,12 @@ void hv_synic_enable_regs(unsigned int cpu)
 			>> HV_HYP_PAGE_SHIFT;
 	}
 
-	hv_set_register(HV_REGISTER_SIEFP, siefp.as_uint64);
+	hv_set_msr(HV_MSR_SIEFP, siefp.as_uint64);
 
 	/* Setup the shared SINT. */
 	if (vmbus_irq != -1)
 		enable_percpu_irq(vmbus_irq, 0);
-	shared_sint.as_uint64 = hv_get_register(HV_REGISTER_SINT0 +
-					VMBUS_MESSAGE_SINT);
+	shared_sint.as_uint64 = hv_get_msr(HV_MSR_SINT0 + VMBUS_MESSAGE_SINT);
 
 	shared_sint.vector = vmbus_interrupt;
 	shared_sint.masked = false;
@@ -326,14 +325,13 @@ void hv_synic_enable_regs(unsigned int cpu)
 #else
 	shared_sint.auto_eoi = 0;
 #endif
-	hv_set_register(HV_REGISTER_SINT0 + VMBUS_MESSAGE_SINT,
-				shared_sint.as_uint64);
+	hv_set_msr(HV_MSR_SINT0 + VMBUS_MESSAGE_SINT, shared_sint.as_uint64);
 
 	/* Enable the global synic bit */
-	sctrl.as_uint64 = hv_get_register(HV_REGISTER_SCONTROL);
+	sctrl.as_uint64 = hv_get_msr(HV_MSR_SCONTROL);
 	sctrl.enable = 1;
 
-	hv_set_register(HV_REGISTER_SCONTROL, sctrl.as_uint64);
+	hv_set_msr(HV_MSR_SCONTROL, sctrl.as_uint64);
 }
 
 int hv_synic_init(unsigned int cpu)
@@ -357,17 +355,15 @@ void hv_synic_disable_regs(unsigned int cpu)
 	union hv_synic_siefp siefp;
 	union hv_synic_scontrol sctrl;
 
-	shared_sint.as_uint64 = hv_get_register(HV_REGISTER_SINT0 +
-					VMBUS_MESSAGE_SINT);
+	shared_sint.as_uint64 = hv_get_msr(HV_MSR_SINT0 + VMBUS_MESSAGE_SINT);
 
 	shared_sint.masked = 1;
 
 	/* Need to correctly cleanup in the case of SMP!!! */
 	/* Disable the interrupt */
-	hv_set_register(HV_REGISTER_SINT0 + VMBUS_MESSAGE_SINT,
-				shared_sint.as_uint64);
+	hv_set_msr(HV_MSR_SINT0 + VMBUS_MESSAGE_SINT, shared_sint.as_uint64);
 
-	simp.as_uint64 = hv_get_register(HV_REGISTER_SIMP);
+	simp.as_uint64 = hv_get_msr(HV_MSR_SIMP);
 	/*
 	 * In Isolation VM, sim and sief pages are allocated by
 	 * paravisor. These pages also will be used by kdump
@@ -382,9 +378,9 @@ void hv_synic_disable_regs(unsigned int cpu)
 		simp.base_simp_gpa = 0;
 	}
 
-	hv_set_register(HV_REGISTER_SIMP, simp.as_uint64);
+	hv_set_msr(HV_MSR_SIMP, simp.as_uint64);
 
-	siefp.as_uint64 = hv_get_register(HV_REGISTER_SIEFP);
+	siefp.as_uint64 = hv_get_msr(HV_MSR_SIEFP);
 	siefp.siefp_enabled = 0;
 
 	if (ms_hyperv.paravisor_present || hv_root_partition) {
@@ -394,12 +390,12 @@ void hv_synic_disable_regs(unsigned int cpu)
 		siefp.base_siefp_gpa = 0;
 	}
 
-	hv_set_register(HV_REGISTER_SIEFP, siefp.as_uint64);
+	hv_set_msr(HV_MSR_SIEFP, siefp.as_uint64);
 
 	/* Disable the global synic bit */
-	sctrl.as_uint64 = hv_get_register(HV_REGISTER_SCONTROL);
+	sctrl.as_uint64 = hv_get_msr(HV_MSR_SCONTROL);
 	sctrl.enable = 0;
-	hv_set_register(HV_REGISTER_SCONTROL, sctrl.as_uint64);
+	hv_set_msr(HV_MSR_SCONTROL, sctrl.as_uint64);
 
 	if (vmbus_irq != -1)
 		disable_percpu_irq(vmbus_irq);
diff --git a/drivers/hv/hv_common.c b/drivers/hv/hv_common.c
index 0285a74363b3..dde3f9b6871a 100644
--- a/drivers/hv/hv_common.c
+++ b/drivers/hv/hv_common.c
@@ -20,8 +20,11 @@
 #include <linux/sched/task_stack.h>
 #include <linux/panic_notifier.h>
 #include <linux/ptrace.h>
+#include <linux/random.h>
+#include <linux/efi.h>
 #include <linux/kdebug.h>
 #include <linux/kmsg_dump.h>
+#include <linux/sizes.h>
 #include <linux/slab.h>
 #include <linux/dma-map-ops.h>
 #include <linux/set_memory.h>
@@ -227,19 +230,19 @@ static void hv_kmsg_dump(struct kmsg_dumper *dumper,
 	 * contain the size of the panic data in that page. Rest of the
 	 * registers are no-op when the NOTIFY_MSG flag is set.
 	 */
-	hv_set_register(HV_REGISTER_CRASH_P0, 0);
-	hv_set_register(HV_REGISTER_CRASH_P1, 0);
-	hv_set_register(HV_REGISTER_CRASH_P2, 0);
-	hv_set_register(HV_REGISTER_CRASH_P3, virt_to_phys(hv_panic_page));
-	hv_set_register(HV_REGISTER_CRASH_P4, bytes_written);
+	hv_set_msr(HV_MSR_CRASH_P0, 0);
+	hv_set_msr(HV_MSR_CRASH_P1, 0);
+	hv_set_msr(HV_MSR_CRASH_P2, 0);
+	hv_set_msr(HV_MSR_CRASH_P3, virt_to_phys(hv_panic_page));
+	hv_set_msr(HV_MSR_CRASH_P4, bytes_written);
 
 	/*
 	 * Let Hyper-V know there is crash data available along with
 	 * the panic message.
 	 */
-	hv_set_register(HV_REGISTER_CRASH_CTL,
-			(HV_CRASH_CTL_CRASH_NOTIFY |
-			 HV_CRASH_CTL_CRASH_NOTIFY_MSG));
+	hv_set_msr(HV_MSR_CRASH_CTL,
+		   (HV_CRASH_CTL_CRASH_NOTIFY |
+		    HV_CRASH_CTL_CRASH_NOTIFY_MSG));
 }
 
 static struct kmsg_dumper hv_kmsg_dumper = {
@@ -278,6 +281,14 @@ 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;
@@ -310,7 +321,7 @@ int __init hv_common_init(void)
 		 * Register for panic kmsg callback only if the right
 		 * capability is supported by the hypervisor.
 		 */
-		hyperv_crash_ctl = hv_get_register(HV_REGISTER_CRASH_CTL);
+		hyperv_crash_ctl = hv_get_msr(HV_MSR_CRASH_CTL);
 		if (hyperv_crash_ctl & HV_CRASH_CTL_CRASH_NOTIFY_MSG)
 			hv_kmsg_dump_register();
 
@@ -347,6 +358,72 @@ int __init hv_common_init(void)
 	return 0;
 }
 
+void __init ms_hyperv_late_init(void)
+{
+	struct acpi_table_header *header;
+	acpi_status status;
+	u8 *randomdata;
+	u32 length, i;
+
+	/*
+	 * Seed the Linux random number generator with entropy provided by
+	 * the Hyper-V host in ACPI table OEM0.
+	 */
+	if (!IS_ENABLED(CONFIG_ACPI))
+		return;
+
+	status = acpi_get_table("OEM0", 0, &header);
+	if (ACPI_FAILURE(status) || !header)
+		return;
+
+	/*
+	 * Since the "OEM0" table name is for OEM specific usage, verify
+	 * that what we're seeing purports to be from Microsoft.
+	 */
+	if (strncmp(header->oem_table_id, "MICROSFT", 8))
+		goto error;
+
+	/*
+	 * Ensure the length is reasonable. Requiring at least 8 bytes and
+	 * no more than 4K bytes is somewhat arbitrary and just protects
+	 * against a malformed table. Hyper-V currently provides 64 bytes,
+	 * but allow for a change in a later version.
+	 */
+	if (header->length < sizeof(*header) + 8 ||
+	    header->length > sizeof(*header) + SZ_4K)
+		goto error;
+
+	length = header->length - sizeof(*header);
+	randomdata = (u8 *)(header + 1);
+
+	pr_debug("Hyper-V: Seeding rng with %d random bytes from ACPI table OEM0\n",
+			length);
+
+	add_bootloader_randomness(randomdata, length);
+
+	/*
+	 * To prevent the seed data from being visible in /sys/firmware/acpi,
+	 * zero out the random data in the ACPI table and fixup the checksum.
+	 * The zero'ing is done out of an abundance of caution in avoiding
+	 * potential security risks to the rng. Similarly, reset the table
+	 * length to just the header size so that a subsequent kexec doesn't
+	 * try to use the zero'ed out random data.
+	 */
+	for (i = 0; i < length; i++) {
+		header->checksum += randomdata[i];
+		randomdata[i] = 0;
+	}
+
+	for (i = 0; i < sizeof(header->length); i++)
+		header->checksum += ((u8 *)&header->length)[i];
+	header->length = sizeof(*header);
+	for (i = 0; i < sizeof(header->length); i++)
+		header->checksum -= ((u8 *)&header->length)[i];
+
+error:
+	acpi_put_table(header);
+}
+
 /*
  * Hyper-V specific initialization and die code for
  * individual CPUs that is common across all architectures.
@@ -409,7 +486,7 @@ int hv_common_cpu_init(unsigned int cpu)
 		*inputarg = mem;
 	}
 
-	msr_vp_index = hv_get_register(HV_REGISTER_VP_INDEX);
+	msr_vp_index = hv_get_msr(HV_MSR_VP_INDEX);
 
 	hv_vp_index[cpu] = msr_vp_index;
 
@@ -506,7 +583,7 @@ EXPORT_SYMBOL_GPL(hv_is_hibernation_supported);
  */
 static u64 __hv_read_ref_counter(void)
 {
-	return hv_get_register(HV_REGISTER_TIME_REF_COUNT);
+	return hv_get_msr(HV_MSR_TIME_REF_COUNT);
 }
 
 u64 (*hv_read_reference_counter)(void) = __hv_read_ref_counter;
diff --git a/drivers/hv/vmbus_drv.c b/drivers/hv/vmbus_drv.c
index 7f7965f3d187..4cb17603a828 100644
--- a/drivers/hv/vmbus_drv.c
+++ b/drivers/hv/vmbus_drv.c
@@ -2359,10 +2359,9 @@ static int vmbus_platform_driver_probe(struct platform_device *pdev)
 		return vmbus_acpi_add(pdev);
 }
 
-static int vmbus_platform_driver_remove(struct platform_device *pdev)
+static void vmbus_platform_driver_remove(struct platform_device *pdev)
 {
 	vmbus_mmio_remove();
-	return 0;
 }
 
 #ifdef CONFIG_PM_SLEEP
@@ -2542,7 +2541,7 @@ static const struct dev_pm_ops vmbus_bus_pm = {
 
 static struct platform_driver vmbus_platform_driver = {
 	.probe = vmbus_platform_driver_probe,
-	.remove = vmbus_platform_driver_remove,
+	.remove_new = vmbus_platform_driver_remove,
 	.driver = {
 		.name = "vmbus",
 		.acpi_match_table = ACPI_PTR(vmbus_acpi_device_ids),
diff --git a/include/asm-generic/hyperv-tlfs.h b/include/asm-generic/hyperv-tlfs.h
index fdac4a1714ec..87e3d49a4e29 100644
--- a/include/asm-generic/hyperv-tlfs.h
+++ b/include/asm-generic/hyperv-tlfs.h
@@ -625,6 +625,37 @@ struct hv_retarget_device_interrupt {
 	struct hv_device_interrupt_target int_target;
 } __packed __aligned(8);
 
+/*
+ * These Hyper-V registers provide information equivalent to the CPUID
+ * instruction on x86/x64.
+ */
+#define HV_REGISTER_HYPERVISOR_VERSION		0x00000100 /*CPUID 0x40000002 */
+#define HV_REGISTER_FEATURES			0x00000200 /*CPUID 0x40000003 */
+#define HV_REGISTER_ENLIGHTENMENTS		0x00000201 /*CPUID 0x40000004 */
+
+/*
+ * Synthetic register definitions equivalent to MSRs on x86/x64
+ */
+#define HV_REGISTER_GUEST_CRASH_P0	0x00000210
+#define HV_REGISTER_GUEST_CRASH_P1	0x00000211
+#define HV_REGISTER_GUEST_CRASH_P2	0x00000212
+#define HV_REGISTER_GUEST_CRASH_P3	0x00000213
+#define HV_REGISTER_GUEST_CRASH_P4	0x00000214
+#define HV_REGISTER_GUEST_CRASH_CTL	0x00000215
+
+#define HV_REGISTER_GUEST_OS_ID		0x00090002
+#define HV_REGISTER_VP_INDEX		0x00090003
+#define HV_REGISTER_TIME_REF_COUNT	0x00090004
+#define HV_REGISTER_REFERENCE_TSC	0x00090017
+
+#define HV_REGISTER_SINT0		0x000A0000
+#define HV_REGISTER_SCONTROL		0x000A0010
+#define HV_REGISTER_SIEFP		0x000A0012
+#define HV_REGISTER_SIMP		0x000A0013
+#define HV_REGISTER_EOM			0x000A0014
+
+#define HV_REGISTER_STIMER0_CONFIG	0x000B0000
+#define HV_REGISTER_STIMER0_COUNT	0x000B0001
 
 /* HvGetVpRegisters hypercall input with variable size reg name list*/
 struct hv_get_vp_registers_input {
@@ -640,7 +671,6 @@ struct hv_get_vp_registers_input {
 	} element[];
 } __packed;
 
-
 /* HvGetVpRegisters returns an array of these output elements */
 struct hv_get_vp_registers_output {
 	union {
@@ -788,6 +818,29 @@ struct hv_input_unmap_device_interrupt {
 #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 430f0ae0dde2..99935779682d 100644
--- a/include/asm-generic/mshyperv.h
+++ b/include/asm-generic/mshyperv.h
@@ -157,10 +157,12 @@ static inline void vmbus_signal_eom(struct hv_message *msg, u32 old_msg_type)
 		 * possibly deliver another msg from the
 		 * hypervisor
 		 */
-		hv_set_register(HV_REGISTER_EOM, 0);
+		hv_set_msr(HV_MSR_EOM, 0);
 	}
 }
 
+int hv_get_hypervisor_version(union hv_hypervisor_version_info *info);
+
 void hv_setup_vmbus_handler(void (*handler)(void));
 void hv_remove_vmbus_handler(void);
 void hv_setup_stimer0_handler(void (*handler)(void));
@@ -193,6 +195,7 @@ extern u64 (*hv_read_reference_counter)(void);
 
 int __init hv_common_init(void);
 void __init hv_common_free(void);
+void __init ms_hyperv_late_init(void);
 int hv_common_cpu_init(unsigned int cpu);
 int hv_common_cpu_die(unsigned int cpu);
 
@@ -290,6 +293,7 @@ void hv_setup_dma_ops(struct device *dev, bool coherent);
 static inline bool hv_is_hyperv_initialized(void) { return false; }
 static inline bool hv_is_hibernation_supported(void) { return false; }
 static inline void hyperv_cleanup(void) {}
+static inline void ms_hyperv_late_init(void) {}
 static inline bool hv_is_isolation_supported(void) { return false; }
 static inline enum hv_isolation_type hv_get_isolation_type(void)
 {