Merge tag 'hyperv-next-signed-20230424' of git://git.kernel.org/pub/scm/linux/kernel/git/hyperv/linux

Pull hyperv updates from Wei Liu:

 - PCI passthrough for Hyper-V confidential VMs (Michael Kelley)

 - Hyper-V VTL mode support (Saurabh Sengar)

 - Move panic report initialization code earlier (Long Li)

 - Various improvements and bug fixes (Dexuan Cui and Michael Kelley)

* tag 'hyperv-next-signed-20230424' of git://git.kernel.org/pub/scm/linux/kernel/git/hyperv/linux: (22 commits)
  PCI: hv: Replace retarget_msi_interrupt_params with hyperv_pcpu_input_arg
  Drivers: hv: move panic report code from vmbus to hv early init code
  x86/hyperv: VTL support for Hyper-V
  Drivers: hv: Kconfig: Add HYPERV_VTL_MODE
  x86/hyperv: Make hv_get_nmi_reason public
  x86/hyperv: Add VTL specific structs and hypercalls
  x86/init: Make get/set_rtc_noop() public
  x86/hyperv: Exclude lazy TLB mode CPUs from enlightened TLB flushes
  x86/hyperv: Add callback filter to cpumask_to_vpset()
  Drivers: hv: vmbus: Remove the per-CPU post_msg_page
  clocksource: hyper-v: make sure Invariant-TSC is used if it is available
  PCI: hv: Enable PCI pass-thru devices in Confidential VMs
  Drivers: hv: Don't remap addresses that are above shared_gpa_boundary
  hv_netvsc: Remove second mapping of send and recv buffers
  Drivers: hv: vmbus: Remove second way of mapping ring buffers
  Drivers: hv: vmbus: Remove second mapping of VMBus monitor pages
  swiotlb: Remove bounce buffer remapping for Hyper-V
  Driver: VMBus: Add Devicetree support
  dt-bindings: bus: Add Hyper-V VMBus
  Drivers: hv: vmbus: Convert acpi_device to more generic platform_device
  ...

Documentation/devicetree/bindings/bus/microsoft,vmbus.yaml

@@ -0,0 +1,54 @@
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/bus/microsoft,vmbus.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Microsoft Hyper-V VMBus
+
+maintainers:
+  - Saurabh Sengar <ssengar@linux.microsoft.com>
+
+description:
+  VMBus is a software bus that implement the protocols for communication
+  between the root or host OS and guest OSs (virtual machines).
+
+properties:
+  compatible:
+    const: microsoft,vmbus
+
+  ranges: true
+
+  '#address-cells':
+    const: 2
+
+  '#size-cells':
+    const: 1
+
+required:
+  - compatible
+  - ranges
+  - '#address-cells'
+  - '#size-cells'
+
+additionalProperties: false
+
+examples:
+  - |
+    soc {
+        #address-cells = <2>;
+        #size-cells = <1>;
+        bus {
+            compatible = "simple-bus";
+            #address-cells = <2>;
+            #size-cells = <1>;
+            ranges;
+
+            vmbus@ff0000000 {
+                compatible = "microsoft,vmbus";
+                #address-cells = <2>;
+                #size-cells = <1>;
+                ranges = <0x0f 0xf0000000 0x0f 0xf0000000 0x10000000>;
+            };
+        };
+    };

MAINTAINERS

@@ -9588,6 +9588,7 @@ S:	Supported
 T:	git git://git.kernel.org/pub/scm/linux/kernel/git/hyperv/linux.git
 F:	Documentation/ABI/stable/sysfs-bus-vmbus
 F:	Documentation/ABI/testing/debugfs-hyperv
+F:	Documentation/devicetree/bindings/bus/microsoft,vmbus.yaml
 F:	Documentation/virt/hyperv
 F:	Documentation/networking/device_drivers/ethernet/microsoft/netvsc.rst
 F:	arch/arm64/hyperv

arch/x86/hyperv/Makefile

@@ -1,6 +1,7 @@
 # SPDX-License-Identifier: GPL-2.0-only
 obj-y			:= hv_init.o mmu.o nested.o irqdomain.o ivm.o
 obj-$(CONFIG_X86_64)	+= hv_apic.o hv_proc.o
+obj-$(CONFIG_HYPERV_VTL_MODE)	+= hv_vtl.o
 
 ifdef CONFIG_X86_64
 obj-$(CONFIG_PARAVIRT_SPINLOCKS)	+= hv_spinlock.o

arch/x86/hyperv/hv_apic.c

@@ -96,6 +96,11 @@ static void hv_apic_eoi_write(u32 reg, u32 val)
 	wrmsr(HV_X64_MSR_EOI, val, 0);
 }
 
+static bool cpu_is_self(int cpu)
+{
+	return cpu == smp_processor_id();
+}
+
 /*
  * IPI implementation on Hyper-V.
  */
@@ -128,10 +133,9 @@ static bool __send_ipi_mask_ex(const struct cpumask *mask, int vector,
 	 */
 	if (!cpumask_equal(mask, cpu_present_mask) || exclude_self) {
 		ipi_arg->vp_set.format = HV_GENERIC_SET_SPARSE_4K;
-		if (exclude_self)
-			nr_bank = cpumask_to_vpset_noself(&(ipi_arg->vp_set), mask);
-		else
-			nr_bank = cpumask_to_vpset(&(ipi_arg->vp_set), mask);
+
+		nr_bank = cpumask_to_vpset_skip(&(ipi_arg->vp_set), mask,
+				exclude_self ? cpu_is_self : NULL);
 
 		/*
 		 * 'nr_bank <= 0' means some CPUs in cpumask can't be

arch/x86/hyperv/hv_init.c

@@ -63,7 +63,10 @@ static int hyperv_init_ghcb(void)
 	 * memory boundary and map it here.
 	 */
 	rdmsrl(MSR_AMD64_SEV_ES_GHCB, ghcb_gpa);
-	ghcb_va = memremap(ghcb_gpa, HV_HYP_PAGE_SIZE, MEMREMAP_WB);
+
+	/* Mask out vTOM bit. ioremap_cache() maps decrypted */
+	ghcb_gpa &= ~ms_hyperv.shared_gpa_boundary;
+	ghcb_va = (void *)ioremap_cache(ghcb_gpa, HV_HYP_PAGE_SIZE);
 	if (!ghcb_va)
 		return -ENOMEM;
 
@@ -217,7 +220,7 @@ static int hv_cpu_die(unsigned int cpu)
 	if (hv_ghcb_pg) {
 		ghcb_va = (void **)this_cpu_ptr(hv_ghcb_pg);
 		if (*ghcb_va)
-			memunmap(*ghcb_va);
+			iounmap(*ghcb_va);
 		*ghcb_va = NULL;
 	}
 

arch/x86/hyperv/hv_vtl.c

@@ -0,0 +1,227 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (c) 2023, Microsoft Corporation.
+ *
+ * Author:
+ *   Saurabh Sengar <ssengar@microsoft.com>
+ */
+
+#include <asm/apic.h>
+#include <asm/boot.h>
+#include <asm/desc.h>
+#include <asm/i8259.h>
+#include <asm/mshyperv.h>
+#include <asm/realmode.h>
+
+extern struct boot_params boot_params;
+static struct real_mode_header hv_vtl_real_mode_header;
+
+void __init hv_vtl_init_platform(void)
+{
+	pr_info("Linux runs in Hyper-V Virtual Trust Level\n");
+
+	x86_init.irqs.pre_vector_init = x86_init_noop;
+	x86_init.timers.timer_init = x86_init_noop;
+
+	x86_platform.get_wallclock = get_rtc_noop;
+	x86_platform.set_wallclock = set_rtc_noop;
+	x86_platform.get_nmi_reason = hv_get_nmi_reason;
+
+	x86_platform.legacy.i8042 = X86_LEGACY_I8042_PLATFORM_ABSENT;
+	x86_platform.legacy.rtc = 0;
+	x86_platform.legacy.warm_reset = 0;
+	x86_platform.legacy.reserve_bios_regions = 0;
+	x86_platform.legacy.devices.pnpbios = 0;
+}
+
+static inline u64 hv_vtl_system_desc_base(struct ldttss_desc *desc)
+{
+	return ((u64)desc->base3 << 32) | ((u64)desc->base2 << 24) |
+		(desc->base1 << 16) | desc->base0;
+}
+
+static inline u32 hv_vtl_system_desc_limit(struct ldttss_desc *desc)
+{
+	return ((u32)desc->limit1 << 16) | (u32)desc->limit0;
+}
+
+typedef void (*secondary_startup_64_fn)(void*, void*);
+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)
+{
+	u64 status;
+	int ret = 0;
+	struct hv_enable_vp_vtl *input;
+	unsigned long irq_flags;
+
+	struct desc_ptr gdt_ptr;
+	struct desc_ptr idt_ptr;
+
+	struct ldttss_desc *tss;
+	struct ldttss_desc *ldt;
+	struct desc_struct *gdt;
+
+	u64 rsp = current->thread.sp;
+	u64 rip = (u64)&hv_vtl_ap_entry;
+
+	native_store_gdt(&gdt_ptr);
+	store_idt(&idt_ptr);
+
+	gdt = (struct desc_struct *)((void *)(gdt_ptr.address));
+	tss = (struct ldttss_desc *)(gdt + GDT_ENTRY_TSS);
+	ldt = (struct ldttss_desc *)(gdt + GDT_ENTRY_LDT);
+
+	local_irq_save(irq_flags);
+
+	input = *this_cpu_ptr(hyperv_pcpu_input_arg);
+	memset(input, 0, sizeof(*input));
+
+	input->partition_id = HV_PARTITION_ID_SELF;
+	input->vp_index = target_vp_index;
+	input->target_vtl.target_vtl = HV_VTL_MGMT;
+
+	/*
+	 * The x86_64 Linux kernel follows the 16-bit -> 32-bit -> 64-bit
+	 * mode transition sequence after waking up an AP with SIPI whose
+	 * vector points to the 16-bit AP startup trampoline code. Here in
+	 * VTL2, we can't perform that sequence as the AP has to start in
+	 * the 64-bit mode.
+	 *
+	 * To make this happen, we tell the hypervisor to load a valid 64-bit
+	 * context (most of which is just magic numbers from the CPU manual)
+	 * so that AP jumps right to the 64-bit entry of the kernel, and the
+	 * control registers are loaded with values that let the AP fetch the
+	 * code and data and carry on with work it gets assigned.
+	 */
+
+	input->vp_context.rip = rip;
+	input->vp_context.rsp = rsp;
+	input->vp_context.rflags = 0x0000000000000002;
+	input->vp_context.efer = __rdmsr(MSR_EFER);
+	input->vp_context.cr0 = native_read_cr0();
+	input->vp_context.cr3 = __native_read_cr3();
+	input->vp_context.cr4 = native_read_cr4();
+	input->vp_context.msr_cr_pat = __rdmsr(MSR_IA32_CR_PAT);
+	input->vp_context.idtr.limit = idt_ptr.size;
+	input->vp_context.idtr.base = idt_ptr.address;
+	input->vp_context.gdtr.limit = gdt_ptr.size;
+	input->vp_context.gdtr.base = gdt_ptr.address;
+
+	/* Non-system desc (64bit), long, code, present */
+	input->vp_context.cs.selector = __KERNEL_CS;
+	input->vp_context.cs.base = 0;
+	input->vp_context.cs.limit = 0xffffffff;
+	input->vp_context.cs.attributes = 0xa09b;
+	/* Non-system desc (64bit), data, present, granularity, default */
+	input->vp_context.ss.selector = __KERNEL_DS;
+	input->vp_context.ss.base = 0;
+	input->vp_context.ss.limit = 0xffffffff;
+	input->vp_context.ss.attributes = 0xc093;
+
+	/* System desc (128bit), present, LDT */
+	input->vp_context.ldtr.selector = GDT_ENTRY_LDT * 8;
+	input->vp_context.ldtr.base = hv_vtl_system_desc_base(ldt);
+	input->vp_context.ldtr.limit = hv_vtl_system_desc_limit(ldt);
+	input->vp_context.ldtr.attributes = 0x82;
+
+	/* System desc (128bit), present, TSS, 0x8b - busy, 0x89 -- default */
+	input->vp_context.tr.selector = GDT_ENTRY_TSS * 8;
+	input->vp_context.tr.base = hv_vtl_system_desc_base(tss);
+	input->vp_context.tr.limit = hv_vtl_system_desc_limit(tss);
+	input->vp_context.tr.attributes = 0x8b;
+
+	status = hv_do_hypercall(HVCALL_ENABLE_VP_VTL, input, NULL);
+
+	if (!hv_result_success(status) &&
+	    hv_result(status) != HV_STATUS_VTL_ALREADY_ENABLED) {
+		pr_err("HVCALL_ENABLE_VP_VTL failed for VP : %d ! [Err: %#llx\n]",
+		       target_vp_index, status);
+		ret = -EINVAL;
+		goto free_lock;
+	}
+
+	status = hv_do_hypercall(HVCALL_START_VP, input, NULL);
+
+	if (!hv_result_success(status)) {
+		pr_err("HVCALL_START_VP failed for VP : %d ! [Err: %#llx]\n",
+		       target_vp_index, status);
+		ret = -EINVAL;
+	}
+
+free_lock:
+	local_irq_restore(irq_flags);
+
+	return ret;
+}
+
+static int hv_vtl_apicid_to_vp_id(u32 apic_id)
+{
+	u64 control;
+	u64 status;
+	unsigned long irq_flags;
+	struct hv_get_vp_from_apic_id_in *input;
+	u32 *output, ret;
+
+	local_irq_save(irq_flags);
+
+	input = *this_cpu_ptr(hyperv_pcpu_input_arg);
+	memset(input, 0, sizeof(*input));
+	input->partition_id = HV_PARTITION_ID_SELF;
+	input->apic_ids[0] = apic_id;
+
+	output = (u32 *)input;
+
+	control = HV_HYPERCALL_REP_COMP_1 | HVCALL_GET_VP_ID_FROM_APIC_ID;
+	status = hv_do_hypercall(control, input, output);
+	ret = output[0];
+
+	local_irq_restore(irq_flags);
+
+	if (!hv_result_success(status)) {
+		pr_err("failed to get vp id from apic id %d, status %#llx\n",
+		       apic_id, status);
+		return -EINVAL;
+	}
+
+	return ret;
+}
+
+static int hv_vtl_wakeup_secondary_cpu(int apicid, unsigned long start_eip)
+{
+	int vp_id;
+
+	pr_debug("Bringing up CPU with APIC ID %d in VTL2...\n", apicid);
+	vp_id = hv_vtl_apicid_to_vp_id(apicid);
+
+	if (vp_id < 0) {
+		pr_err("Couldn't find CPU with APIC ID %d\n", apicid);
+		return -EINVAL;
+	}
+	if (vp_id > ms_hyperv.max_vp_index) {
+		pr_err("Invalid CPU id %d for APIC ID %d\n", vp_id, apicid);
+		return -EINVAL;
+	}
+
+	return hv_vtl_bringup_vcpu(vp_id, start_eip);
+}
+
+static int __init hv_vtl_early_init(void)
+{
+	/*
+	 * `boot_cpu_has` returns the runtime feature support,
+	 * and here is the earliest it can be used.
+	 */
+	if (cpu_feature_enabled(X86_FEATURE_XSAVE))
+		panic("XSAVE has to be disabled as it is not supported by this module.\n"
+			  "Please add 'noxsave' to the kernel command line.\n");
+
+	real_mode_header = &hv_vtl_real_mode_header;
+	apic->wakeup_secondary_cpu_64 = hv_vtl_wakeup_secondary_cpu;
+
+	return 0;
+}
+early_initcall(hv_vtl_early_init);

arch/x86/hyperv/ivm.c

@@ -376,34 +376,6 @@ void __init hv_vtom_init(void)
 
 #endif /* CONFIG_AMD_MEM_ENCRYPT */
 
-/*
- * hv_map_memory - map memory to extra space in the AMD SEV-SNP Isolation VM.
- */
-void *hv_map_memory(void *addr, unsigned long size)
-{
-	unsigned long *pfns = kcalloc(size / PAGE_SIZE,
-				      sizeof(unsigned long), GFP_KERNEL);
-	void *vaddr;
-	int i;
-
-	if (!pfns)
-		return NULL;
-
-	for (i = 0; i < size / PAGE_SIZE; i++)
-		pfns[i] = vmalloc_to_pfn(addr + i * PAGE_SIZE) +
-			(ms_hyperv.shared_gpa_boundary >> PAGE_SHIFT);
-
-	vaddr = vmap_pfn(pfns, size / PAGE_SIZE, pgprot_decrypted(PAGE_KERNEL));
-	kfree(pfns);
-
-	return vaddr;
-}
-
-void hv_unmap_memory(void *addr)
-{
-	vunmap(addr);
-}
-
 enum hv_isolation_type hv_get_isolation_type(void)
 {
 	if (!(ms_hyperv.priv_high & HV_ISOLATION))

arch/x86/hyperv/mmu.c

@@ -52,6 +52,11 @@ static inline int fill_gva_list(u64 gva_list[], int offset,
 	return gva_n - offset;
 }
 
+static bool cpu_is_lazy(int cpu)
+{
+	return per_cpu(cpu_tlbstate_shared.is_lazy, cpu);
+}
+
 static void hyperv_flush_tlb_multi(const struct cpumask *cpus,
 				   const struct flush_tlb_info *info)
 {
@@ -60,6 +65,7 @@ static void hyperv_flush_tlb_multi(const struct cpumask *cpus,
 	struct hv_tlb_flush *flush;
 	u64 status;
 	unsigned long flags;
+	bool do_lazy = !info->freed_tables;
 
 	trace_hyperv_mmu_flush_tlb_multi(cpus, info);
 
@@ -112,6 +118,8 @@ static void hyperv_flush_tlb_multi(const struct cpumask *cpus,
 			goto do_ex_hypercall;
 
 		for_each_cpu(cpu, cpus) {
+			if (do_lazy && cpu_is_lazy(cpu))
+				continue;
 			vcpu = hv_cpu_number_to_vp_number(cpu);
 			if (vcpu == VP_INVAL) {
 				local_irq_restore(flags);
@@ -198,7 +206,8 @@ static u64 hyperv_flush_tlb_others_ex(const struct cpumask *cpus,
 	flush->hv_vp_set.valid_bank_mask = 0;
 
 	flush->hv_vp_set.format = HV_GENERIC_SET_SPARSE_4K;
-	nr_bank = cpumask_to_vpset(&(flush->hv_vp_set), cpus);
+	nr_bank = cpumask_to_vpset_skip(&flush->hv_vp_set, cpus,
+			info->freed_tables ? NULL : cpu_is_lazy);
 	if (nr_bank < 0)
 		return HV_STATUS_INVALID_PARAMETER;
 

arch/x86/include/asm/hyperv-tlfs.h

@@ -122,6 +122,9 @@
 /* Recommend using enlightened VMCS */
 #define HV_X64_ENLIGHTENED_VMCS_RECOMMENDED		BIT(14)
 
+/* Use hypercalls for MMIO config space access */
+#define HV_X64_USE_MMIO_HYPERCALLS			BIT(21)
+
 /*
  * CPU management features identification.
  * These are HYPERV_CPUID_CPU_MANAGEMENT_FEATURES.EAX bits.
@@ -713,6 +716,81 @@ union hv_msi_entry {
 	} __packed;
 };
 
+struct hv_x64_segment_register {
+	u64 base;
+	u32 limit;
+	u16 selector;
+	union {
+		struct {
+			u16 segment_type : 4;
+			u16 non_system_segment : 1;
+			u16 descriptor_privilege_level : 2;
+			u16 present : 1;
+			u16 reserved : 4;
+			u16 available : 1;
+			u16 _long : 1;
+			u16 _default : 1;
+			u16 granularity : 1;
+		} __packed;
+		u16 attributes;
+	};
+} __packed;
+
+struct hv_x64_table_register {
+	u16 pad[3];
+	u16 limit;
+	u64 base;
+} __packed;
+
+struct hv_init_vp_context {
+	u64 rip;
+	u64 rsp;
+	u64 rflags;
+
+	struct hv_x64_segment_register cs;
+	struct hv_x64_segment_register ds;
+	struct hv_x64_segment_register es;
+	struct hv_x64_segment_register fs;
+	struct hv_x64_segment_register gs;
+	struct hv_x64_segment_register ss;
+	struct hv_x64_segment_register tr;
+	struct hv_x64_segment_register ldtr;
+
+	struct hv_x64_table_register idtr;
+	struct hv_x64_table_register gdtr;
+
+	u64 efer;
+	u64 cr0;
+	u64 cr3;
+	u64 cr4;
+	u64 msr_cr_pat;
+} __packed;
+
+union hv_input_vtl {
+	u8 as_uint8;
+	struct {
+		u8 target_vtl: 4;
+		u8 use_target_vtl: 1;
+		u8 reserved_z: 3;
+	};
+} __packed;
+
+struct hv_enable_vp_vtl {
+	u64				partition_id;
+	u32				vp_index;
+	union hv_input_vtl		target_vtl;
+	u8				mbz0;
+	u16				mbz1;
+	struct hv_init_vp_context	vp_context;
+} __packed;
+
+struct hv_get_vp_from_apic_id_in {
+	u64 partition_id;
+	union hv_input_vtl target_vtl;
+	u8 res[7];
+	u32 apic_ids[];
+} __packed;
+
 #include <asm-generic/hyperv-tlfs.h>
 
 #endif

arch/x86/include/asm/mshyperv.h

@@ -19,6 +19,10 @@
  */
 #define HV_IOAPIC_BASE_ADDRESS 0xfec00000
 
+#define HV_VTL_NORMAL 0x0
+#define HV_VTL_SECURE 0x1
+#define HV_VTL_MGMT   0x2
+
 union hv_ghcb;
 
 DECLARE_STATIC_KEY_FALSE(isolation_type_snp);
@@ -29,6 +33,11 @@ typedef int (*hyperv_fill_flush_list_func)(
 
 void hyperv_vector_handler(struct pt_regs *regs);
 
+static inline unsigned char hv_get_nmi_reason(void)
+{
+	return 0;
+}
+
 #if IS_ENABLED(CONFIG_HYPERV)
 extern int hyperv_init_cpuhp;
 
@@ -271,6 +280,12 @@ static inline u64 hv_get_non_nested_register(unsigned int reg) { return 0; }
 #endif /* CONFIG_HYPERV */
 
 
+#ifdef CONFIG_HYPERV_VTL_MODE
+void __init hv_vtl_init_platform(void);
+#else
+static inline void __init hv_vtl_init_platform(void) {}
+#endif
+
 #include <asm-generic/mshyperv.h>
 
 #endif

arch/x86/include/asm/x86_init.h

@@ -330,5 +330,7 @@ extern void x86_init_uint_noop(unsigned int unused);
 extern bool bool_x86_init_noop(void);
 extern void x86_op_int_noop(int cpu);
 extern bool x86_pnpbios_disabled(void);
+extern int set_rtc_noop(const struct timespec64 *now);
+extern void get_rtc_noop(struct timespec64 *now);
 
 #endif

arch/x86/kernel/cpu/mshyperv.c

@@ -18,7 +18,6 @@
 #include <linux/kexec.h>
 #include <linux/i8253.h>
 #include <linux/random.h>
-#include <linux/swiotlb.h>
 #include <asm/processor.h>
 #include <asm/hypervisor.h>
 #include <asm/hyperv-tlfs.h>
@@ -249,11 +248,6 @@ static uint32_t  __init ms_hyperv_platform(void)
 	return HYPERV_CPUID_VENDOR_AND_MAX_FUNCTIONS;
 }
 
-static unsigned char hv_get_nmi_reason(void)
-{
-	return 0;
-}
-
 #ifdef CONFIG_X86_LOCAL_APIC
 /*
  * Prior to WS2016 Debug-VM sends NMIs to all CPUs which makes
@@ -408,12 +402,8 @@ static void __init ms_hyperv_init_platform(void)
 		pr_info("Hyper-V: Isolation Config: Group A 0x%x, Group B 0x%x\n",
 			ms_hyperv.isolation_config_a, ms_hyperv.isolation_config_b);
 
-		if (hv_get_isolation_type() == HV_ISOLATION_TYPE_SNP) {
+		if (hv_get_isolation_type() == HV_ISOLATION_TYPE_SNP)
 			static_branch_enable(&isolation_type_snp);
-#ifdef CONFIG_SWIOTLB
-			swiotlb_unencrypted_base = ms_hyperv.shared_gpa_boundary;
-#endif
-		}
 	}
 
 	if (hv_max_functions_eax >= HYPERV_CPUID_NESTED_FEATURES) {
@@ -524,6 +514,7 @@ static void __init ms_hyperv_init_platform(void)
 
 	/* Register Hyper-V specific clocksource */
 	hv_init_clocksource();
+	hv_vtl_init_platform();
 #endif
 	/*
 	 * TSC should be marked as unstable only after Hyper-V

arch/x86/kernel/x86_init.c

@@ -33,8 +33,8 @@ static int __init iommu_init_noop(void) { return 0; }
 static void iommu_shutdown_noop(void) { }
 bool __init bool_x86_init_noop(void) { return false; }
 void x86_op_int_noop(int cpu) { }
-static int set_rtc_noop(const struct timespec64 *now) { return -EINVAL; }
-static void get_rtc_noop(struct timespec64 *now) { }
+int set_rtc_noop(const struct timespec64 *now) { return -EINVAL; }
+void get_rtc_noop(struct timespec64 *now) { }
 
 static __initconst const struct of_device_id of_cmos_match[] = {
 	{ .compatible = "motorola,mc146818" },

drivers/clocksource/hyperv_timer.c

@@ -49,7 +49,7 @@ static bool direct_mode_enabled;
 
 static int stimer0_irq = -1;
 static int stimer0_message_sint;
-static DEFINE_PER_CPU(long, stimer0_evt);
+static __maybe_unused DEFINE_PER_CPU(long, stimer0_evt);
 
 /*
  * Common code for stimer0 interrupts coming via Direct Mode or
@@ -68,7 +68,7 @@ EXPORT_SYMBOL_GPL(hv_stimer0_isr);
  * stimer0 interrupt handler for architectures that support
  * per-cpu interrupts, which also implies Direct Mode.
  */
-static irqreturn_t hv_stimer0_percpu_isr(int irq, void *dev_id)
+static irqreturn_t __maybe_unused hv_stimer0_percpu_isr(int irq, void *dev_id)
 {
 	hv_stimer0_isr();
 	return IRQ_HANDLED;
@@ -196,6 +196,7 @@ void __weak hv_remove_stimer0_handler(void)
 {
 };
 
+#ifdef CONFIG_ACPI
 /* Called only on architectures with per-cpu IRQs (i.e., not x86/x64) */
 static int hv_setup_stimer0_irq(void)
 {
@@ -230,6 +231,16 @@ static void hv_remove_stimer0_irq(void)
 		stimer0_irq = -1;
 	}
 }
+#else
+static int hv_setup_stimer0_irq(void)
+{
+	return 0;
+}
+
+static void hv_remove_stimer0_irq(void)
+{
+}
+#endif
 
 /* hv_stimer_alloc - Global initialization of the clockevent and stimer0 */
 int hv_stimer_alloc(bool have_percpu_irqs)
@@ -506,9 +517,6 @@ static bool __init hv_init_tsc_clocksource(void)
 {
 	union hv_reference_tsc_msr tsc_msr;
 
-	if (!(ms_hyperv.features & HV_MSR_REFERENCE_TSC_AVAILABLE))
-		return false;
-
 	/*
 	 * If Hyper-V offers TSC_INVARIANT, then the virtualized TSC correctly
 	 * handles frequency and offset changes due to live migration,
@@ -525,6 +533,9 @@ static bool __init hv_init_tsc_clocksource(void)
 		hyperv_cs_msr.rating = 250;
 	}
 
+	if (!(ms_hyperv.features & HV_MSR_REFERENCE_TSC_AVAILABLE))
+		return false;
+
 	hv_read_reference_counter = read_hv_clock_tsc;
 
 	/*

drivers/hv/Kconfig

@@ -4,15 +4,39 @@ menu "Microsoft Hyper-V guest support"
 
 config HYPERV
 	tristate "Microsoft Hyper-V client drivers"
-	depends on ACPI && ((X86 && X86_LOCAL_APIC && HYPERVISOR_GUEST) \
-		|| (ARM64 && !CPU_BIG_ENDIAN))
+	depends on (X86 && X86_LOCAL_APIC && HYPERVISOR_GUEST) \
+		|| (ACPI && ARM64 && !CPU_BIG_ENDIAN)
 	select PARAVIRT
 	select X86_HV_CALLBACK_VECTOR if X86
-	select VMAP_PFN
+	select OF_EARLY_FLATTREE if OF
 	help
 	  Select this option to run Linux as a Hyper-V client operating
 	  system.
 
+config HYPERV_VTL_MODE
+	bool "Enable Linux to boot in VTL context"
+	depends on X86_64 && HYPERV
+	default n
+	help
+	  Virtual Secure Mode (VSM) is a set of hypervisor capabilities and
+	  enlightenments offered to host and guest partitions which enables
+	  the creation and management of new security boundaries within
+	  operating system software.
+
+	  VSM achieves and maintains isolation through Virtual Trust Levels
+	  (VTLs). Virtual Trust Levels are hierarchical, with higher levels
+	  being more privileged than lower levels. VTL0 is the least privileged
+	  level, and currently only other level supported is VTL2.
+
+	  Select this option to build a Linux kernel to run at a VTL other than
+	  the normal VTL0, which currently is only VTL2.  This option
+	  initializes the x86 platform for VTL2, and adds the ability to boot
+	  secondary CPUs directly into 64-bit context as required for VTLs other
+	  than 0.  A kernel built with this option must run at VTL2, and will
+	  not run as a normal guest.
+
+	  If unsure, say N
+
 config HYPERV_TIMER
 	def_bool HYPERV && X86
 

drivers/hv/channel_mgmt.c

@@ -67,7 +67,7 @@ const struct vmbus_device vmbus_devs[] = {
 	{ .dev_type = HV_PCIE,
 	  HV_PCIE_GUID,
 	  .perf_device = false,
-	  .allowed_in_isolated = false,
+	  .allowed_in_isolated = true,
 	},
 
 	/* Synthetic Frame Buffer */

drivers/hv/connection.c

@@ -104,8 +104,14 @@ int vmbus_negotiate_version(struct vmbus_channel_msginfo *msginfo, u32 version)
 		vmbus_connection.msg_conn_id = VMBUS_MESSAGE_CONNECTION_ID;
 	}
 
-	msg->monitor_page1 = vmbus_connection.monitor_pages_pa[0];
-	msg->monitor_page2 = vmbus_connection.monitor_pages_pa[1];
+	/*
+	 * shared_gpa_boundary is zero in non-SNP VMs, so it's safe to always
+	 * bitwise OR it
+	 */
+	msg->monitor_page1 = virt_to_phys(vmbus_connection.monitor_pages[0]) |
+				ms_hyperv.shared_gpa_boundary;
+	msg->monitor_page2 = virt_to_phys(vmbus_connection.monitor_pages[1]) |
+				ms_hyperv.shared_gpa_boundary;
 
 	msg->target_vcpu = hv_cpu_number_to_vp_number(VMBUS_CONNECT_CPU);
 
@@ -219,72 +225,27 @@ int vmbus_connect(void)
 	 * Setup the monitor notification facility. The 1st page for
 	 * parent->child and the 2nd page for child->parent
 	 */
-	vmbus_connection.monitor_pages[0] = (void *)hv_alloc_hyperv_zeroed_page();
-	vmbus_connection.monitor_pages[1] = (void *)hv_alloc_hyperv_zeroed_page();
+	vmbus_connection.monitor_pages[0] = (void *)hv_alloc_hyperv_page();
+	vmbus_connection.monitor_pages[1] = (void *)hv_alloc_hyperv_page();
 	if ((vmbus_connection.monitor_pages[0] == NULL) ||
 	    (vmbus_connection.monitor_pages[1] == NULL)) {
 		ret = -ENOMEM;
 		goto cleanup;
 	}
 
-	vmbus_connection.monitor_pages_original[0]
-		= vmbus_connection.monitor_pages[0];
-	vmbus_connection.monitor_pages_original[1]
-		= vmbus_connection.monitor_pages[1];
-	vmbus_connection.monitor_pages_pa[0]
-		= virt_to_phys(vmbus_connection.monitor_pages[0]);
-	vmbus_connection.monitor_pages_pa[1]
-		= virt_to_phys(vmbus_connection.monitor_pages[1]);
+	ret = set_memory_decrypted((unsigned long)
+				vmbus_connection.monitor_pages[0], 1);
+	ret |= set_memory_decrypted((unsigned long)
+				vmbus_connection.monitor_pages[1], 1);
+	if (ret)
+		goto cleanup;
 
-	if (hv_is_isolation_supported()) {
-		ret = set_memory_decrypted((unsigned long)
-					   vmbus_connection.monitor_pages[0],
-					   1);
-		ret |= set_memory_decrypted((unsigned long)
-					    vmbus_connection.monitor_pages[1],
-					    1);
-		if (ret)
-			goto cleanup;
-
-		/*
-		 * Isolation VM with AMD SNP needs to access monitor page via
-		 * address space above shared gpa boundary.
-		 */
-		if (hv_isolation_type_snp()) {
-			vmbus_connection.monitor_pages_pa[0] +=
-				ms_hyperv.shared_gpa_boundary;
-			vmbus_connection.monitor_pages_pa[1] +=
-				ms_hyperv.shared_gpa_boundary;
-
-			vmbus_connection.monitor_pages[0]
-				= memremap(vmbus_connection.monitor_pages_pa[0],
-					   HV_HYP_PAGE_SIZE,
-					   MEMREMAP_WB);
-			if (!vmbus_connection.monitor_pages[0]) {
-				ret = -ENOMEM;
-				goto cleanup;
-			}
-
-			vmbus_connection.monitor_pages[1]
-				= memremap(vmbus_connection.monitor_pages_pa[1],
-					   HV_HYP_PAGE_SIZE,
-					   MEMREMAP_WB);
-			if (!vmbus_connection.monitor_pages[1]) {
-				ret = -ENOMEM;
-				goto cleanup;
-			}
-		}
-
-		/*
-		 * Set memory host visibility hvcall smears memory
-		 * and so zero monitor pages here.
-		 */
-		memset(vmbus_connection.monitor_pages[0], 0x00,
-		       HV_HYP_PAGE_SIZE);
-		memset(vmbus_connection.monitor_pages[1], 0x00,
-		       HV_HYP_PAGE_SIZE);
-
-	}
+	/*
+	 * Set_memory_decrypted() will change the memory contents if
+	 * decryption occurs, so zero monitor pages here.
+	 */
+	memset(vmbus_connection.monitor_pages[0], 0x00, HV_HYP_PAGE_SIZE);
+	memset(vmbus_connection.monitor_pages[1], 0x00, HV_HYP_PAGE_SIZE);
 
 	msginfo = kzalloc(sizeof(*msginfo) +
 			  sizeof(struct vmbus_channel_initiate_contact),
@@ -376,31 +337,13 @@ void vmbus_disconnect(void)
 		vmbus_connection.int_page = NULL;
 	}
 
-	if (hv_is_isolation_supported()) {
-		/*
-		 * memunmap() checks input address is ioremap address or not
-		 * inside. It doesn't unmap any thing in the non-SNP CVM and
-		 * so not check CVM type here.
-		 */
-		memunmap(vmbus_connection.monitor_pages[0]);
-		memunmap(vmbus_connection.monitor_pages[1]);
+	set_memory_encrypted((unsigned long)vmbus_connection.monitor_pages[0], 1);
+	set_memory_encrypted((unsigned long)vmbus_connection.monitor_pages[1], 1);
 
-		set_memory_encrypted((unsigned long)
-			vmbus_connection.monitor_pages_original[0],
-			1);
-		set_memory_encrypted((unsigned long)
-			vmbus_connection.monitor_pages_original[1],
-			1);
-	}
-
-	hv_free_hyperv_page((unsigned long)
-		vmbus_connection.monitor_pages_original[0]);
-	hv_free_hyperv_page((unsigned long)
-		vmbus_connection.monitor_pages_original[1]);
-	vmbus_connection.monitor_pages_original[0] =
-		vmbus_connection.monitor_pages[0] = NULL;
-	vmbus_connection.monitor_pages_original[1] =
-		vmbus_connection.monitor_pages[1] = NULL;
+	hv_free_hyperv_page((unsigned long)vmbus_connection.monitor_pages[0]);
+	hv_free_hyperv_page((unsigned long)vmbus_connection.monitor_pages[1]);
+	vmbus_connection.monitor_pages[0] = NULL;
+	vmbus_connection.monitor_pages[1] = NULL;
 }
 
 /*

drivers/hv/hv.c

@@ -38,42 +38,6 @@ int hv_init(void)
 	return 0;
 }
 
-/*
- * Functions for allocating and freeing memory with size and
- * alignment HV_HYP_PAGE_SIZE. These functions are needed because
- * the guest page size may not be the same as the Hyper-V page
- * size. We depend upon kmalloc() aligning power-of-two size
- * allocations to the allocation size boundary, so that the
- * allocated memory appears to Hyper-V as a page of the size
- * it expects.
- */
-
-void *hv_alloc_hyperv_page(void)
-{
-	BUILD_BUG_ON(PAGE_SIZE <  HV_HYP_PAGE_SIZE);
-
-	if (PAGE_SIZE == HV_HYP_PAGE_SIZE)
-		return (void *)__get_free_page(GFP_KERNEL);
-	else
-		return kmalloc(HV_HYP_PAGE_SIZE, GFP_KERNEL);
-}
-
-void *hv_alloc_hyperv_zeroed_page(void)
-{
-	if (PAGE_SIZE == HV_HYP_PAGE_SIZE)
-		return (void *)__get_free_page(GFP_KERNEL | __GFP_ZERO);
-	else
-		return kzalloc(HV_HYP_PAGE_SIZE, GFP_KERNEL);
-}
-
-void hv_free_hyperv_page(unsigned long addr)
-{
-	if (PAGE_SIZE == HV_HYP_PAGE_SIZE)
-		free_page(addr);
-	else
-		kfree((void *)addr);
-}
-
 /*
  * hv_post_message - Post a message using the hypervisor message IPC.
  *
@@ -84,14 +48,15 @@ int hv_post_message(union hv_connection_id connection_id,
 		  void *payload, size_t payload_size)
 {
 	struct hv_input_post_message *aligned_msg;
-	struct hv_per_cpu_context *hv_cpu;
+	unsigned long flags;
 	u64 status;
 
 	if (payload_size > HV_MESSAGE_PAYLOAD_BYTE_COUNT)
 		return -EMSGSIZE;
 
-	hv_cpu = get_cpu_ptr(hv_context.cpu_context);
-	aligned_msg = hv_cpu->post_msg_page;
+	local_irq_save(flags);
+
+	aligned_msg = *this_cpu_ptr(hyperv_pcpu_input_arg);
 	aligned_msg->connectionid = connection_id;
 	aligned_msg->reserved = 0;
 	aligned_msg->message_type = message_type;
@@ -106,11 +71,7 @@ int hv_post_message(union hv_connection_id connection_id,
 		status = hv_do_hypercall(HVCALL_POST_MESSAGE,
 				aligned_msg, NULL);
 
-	/* Preemption must remain disabled until after the hypercall
-	 * so some other thread can't get scheduled onto this cpu and
-	 * corrupt the per-cpu post_msg_page
-	 */
-	put_cpu_ptr(hv_cpu);
+	local_irq_restore(flags);
 
 	return hv_result(status);
 }
@@ -162,12 +123,6 @@ int hv_synic_alloc(void)
 				goto err;
 			}
 		}
-
-		hv_cpu->post_msg_page = (void *)get_zeroed_page(GFP_ATOMIC);
-		if (hv_cpu->post_msg_page == NULL) {
-			pr_err("Unable to allocate post msg page\n");
-			goto err;
-		}
 	}
 
 	return 0;
@@ -190,7 +145,6 @@ void hv_synic_free(void)
 
 		free_page((unsigned long)hv_cpu->synic_event_page);
 		free_page((unsigned long)hv_cpu->synic_message_page);
-		free_page((unsigned long)hv_cpu->post_msg_page);
 	}
 
 	kfree(hv_context.hv_numa_map);
@@ -217,11 +171,13 @@ void hv_synic_enable_regs(unsigned int cpu)
 	simp.simp_enabled = 1;
 
 	if (hv_isolation_type_snp() || hv_root_partition) {
+		/* Mask out vTOM bit. ioremap_cache() maps decrypted */
+		u64 base = (simp.base_simp_gpa << HV_HYP_PAGE_SHIFT) &
+				~ms_hyperv.shared_gpa_boundary;
 		hv_cpu->synic_message_page
-			= memremap(simp.base_simp_gpa << HV_HYP_PAGE_SHIFT,
-				   HV_HYP_PAGE_SIZE, MEMREMAP_WB);
+			= (void *)ioremap_cache(base, HV_HYP_PAGE_SIZE);
 		if (!hv_cpu->synic_message_page)
-			pr_err("Fail to map syinc message page.\n");
+			pr_err("Fail to map synic message page.\n");
 	} else {
 		simp.base_simp_gpa = virt_to_phys(hv_cpu->synic_message_page)
 			>> HV_HYP_PAGE_SHIFT;
@@ -234,12 +190,13 @@ void hv_synic_enable_regs(unsigned int cpu)
 	siefp.siefp_enabled = 1;
 
 	if (hv_isolation_type_snp() || hv_root_partition) {
-		hv_cpu->synic_event_page =
-			memremap(siefp.base_siefp_gpa << HV_HYP_PAGE_SHIFT,
-				 HV_HYP_PAGE_SIZE, MEMREMAP_WB);
-
+		/* Mask out vTOM bit. ioremap_cache() maps decrypted */
+		u64 base = (siefp.base_siefp_gpa << HV_HYP_PAGE_SHIFT) &
+				~ms_hyperv.shared_gpa_boundary;
+		hv_cpu->synic_event_page
+			= (void *)ioremap_cache(base, HV_HYP_PAGE_SIZE);
 		if (!hv_cpu->synic_event_page)
-			pr_err("Fail to map syinc event page.\n");
+			pr_err("Fail to map synic event page.\n");
 	} else {
 		siefp.base_siefp_gpa = virt_to_phys(hv_cpu->synic_event_page)
 			>> HV_HYP_PAGE_SHIFT;
@@ -316,7 +273,7 @@ void hv_synic_disable_regs(unsigned int cpu)
 	 */
 	simp.simp_enabled = 0;
 	if (hv_isolation_type_snp() || hv_root_partition) {
-		memunmap(hv_cpu->synic_message_page);
+		iounmap(hv_cpu->synic_message_page);
 		hv_cpu->synic_message_page = NULL;
 	} else {
 		simp.base_simp_gpa = 0;
@@ -328,7 +285,7 @@ void hv_synic_disable_regs(unsigned int cpu)
 	siefp.siefp_enabled = 0;
 
 	if (hv_isolation_type_snp() || hv_root_partition) {
-		memunmap(hv_cpu->synic_event_page);
+		iounmap(hv_cpu->synic_event_page);
 		hv_cpu->synic_event_page = NULL;
 	} else {
 		siefp.base_siefp_gpa = 0;

drivers/hv/hv_common.c

@@ -17,8 +17,11 @@
 #include <linux/export.h>
 #include <linux/bitfield.h>
 #include <linux/cpumask.h>
+#include <linux/sched/task_stack.h>
 #include <linux/panic_notifier.h>
 #include <linux/ptrace.h>
+#include <linux/kdebug.h>
+#include <linux/kmsg_dump.h>
 #include <linux/slab.h>
 #include <linux/dma-map-ops.h>
 #include <asm/hyperv-tlfs.h>
@@ -54,6 +57,10 @@ EXPORT_SYMBOL_GPL(hyperv_pcpu_input_arg);
 void * __percpu *hyperv_pcpu_output_arg;
 EXPORT_SYMBOL_GPL(hyperv_pcpu_output_arg);
 
+static void hv_kmsg_dump_unregister(void);
+
+static struct ctl_table_header *hv_ctl_table_hdr;
+
 /*
  * Hyper-V specific initialization and shutdown code that is
  * common across all architectures.  Called from architecture
@@ -62,6 +69,12 @@ EXPORT_SYMBOL_GPL(hyperv_pcpu_output_arg);
 
 void __init hv_common_free(void)
 {
+	unregister_sysctl_table(hv_ctl_table_hdr);
+	hv_ctl_table_hdr = NULL;
+
+	if (ms_hyperv.misc_features & HV_FEATURE_GUEST_CRASH_MSR_AVAILABLE)
+		hv_kmsg_dump_unregister();
+
 	kfree(hv_vp_index);
 	hv_vp_index = NULL;
 
@@ -72,10 +85,203 @@ void __init hv_common_free(void)
 	hyperv_pcpu_input_arg = NULL;
 }
 
+/*
+ * Functions for allocating and freeing memory with size and
+ * alignment HV_HYP_PAGE_SIZE. These functions are needed because
+ * the guest page size may not be the same as the Hyper-V page
+ * size. We depend upon kmalloc() aligning power-of-two size
+ * allocations to the allocation size boundary, so that the
+ * allocated memory appears to Hyper-V as a page of the size
+ * it expects.
+ */
+
+void *hv_alloc_hyperv_page(void)
+{
+	BUILD_BUG_ON(PAGE_SIZE <  HV_HYP_PAGE_SIZE);
+
+	if (PAGE_SIZE == HV_HYP_PAGE_SIZE)
+		return (void *)__get_free_page(GFP_KERNEL);
+	else
+		return kmalloc(HV_HYP_PAGE_SIZE, GFP_KERNEL);
+}
+EXPORT_SYMBOL_GPL(hv_alloc_hyperv_page);
+
+void *hv_alloc_hyperv_zeroed_page(void)
+{
+	if (PAGE_SIZE == HV_HYP_PAGE_SIZE)
+		return (void *)__get_free_page(GFP_KERNEL | __GFP_ZERO);
+	else
+		return kzalloc(HV_HYP_PAGE_SIZE, GFP_KERNEL);
+}
+EXPORT_SYMBOL_GPL(hv_alloc_hyperv_zeroed_page);
+
+void hv_free_hyperv_page(unsigned long addr)
+{
+	if (PAGE_SIZE == HV_HYP_PAGE_SIZE)
+		free_page(addr);
+	else
+		kfree((void *)addr);
+}
+EXPORT_SYMBOL_GPL(hv_free_hyperv_page);
+
+static void *hv_panic_page;
+
+/*
+ * Boolean to control whether to report panic messages over Hyper-V.
+ *
+ * It can be set via /proc/sys/kernel/hyperv_record_panic_msg
+ */
+static int sysctl_record_panic_msg = 1;
+
+/*
+ * sysctl option to allow the user to control whether kmsg data should be
+ * reported to Hyper-V on panic.
+ */
+static struct ctl_table hv_ctl_table[] = {
+	{
+		.procname	= "hyperv_record_panic_msg",
+		.data		= &sysctl_record_panic_msg,
+		.maxlen		= sizeof(int),
+		.mode		= 0644,
+		.proc_handler	= proc_dointvec_minmax,
+		.extra1		= SYSCTL_ZERO,
+		.extra2		= SYSCTL_ONE
+	},
+	{}
+};
+
+static int hv_die_panic_notify_crash(struct notifier_block *self,
+				     unsigned long val, void *args);
+
+static struct notifier_block hyperv_die_report_block = {
+	.notifier_call = hv_die_panic_notify_crash,
+};
+
+static struct notifier_block hyperv_panic_report_block = {
+	.notifier_call = hv_die_panic_notify_crash,
+};
+
+/*
+ * The following callback works both as die and panic notifier; its
+ * goal is to provide panic information to the hypervisor unless the
+ * kmsg dumper is used [see hv_kmsg_dump()], which provides more
+ * information but isn't always available.
+ *
+ * Notice that both the panic/die report notifiers are registered only
+ * if we have the capability HV_FEATURE_GUEST_CRASH_MSR_AVAILABLE set.
+ */
+static int hv_die_panic_notify_crash(struct notifier_block *self,
+				     unsigned long val, void *args)
+{
+	struct pt_regs *regs;
+	bool is_die;
+
+	/* Don't notify Hyper-V unless we have a die oops event or panic. */
+	if (self == &hyperv_panic_report_block) {
+		is_die = false;
+		regs = current_pt_regs();
+	} else { /* die event */
+		if (val != DIE_OOPS)
+			return NOTIFY_DONE;
+
+		is_die = true;
+		regs = ((struct die_args *)args)->regs;
+	}
+
+	/*
+	 * Hyper-V should be notified only once about a panic/die. If we will
+	 * be calling hv_kmsg_dump() later with kmsg data, don't do the
+	 * notification here.
+	 */
+	if (!sysctl_record_panic_msg || !hv_panic_page)
+		hyperv_report_panic(regs, val, is_die);
+
+	return NOTIFY_DONE;
+}
+
+/*
+ * Callback from kmsg_dump. Grab as much as possible from the end of the kmsg
+ * buffer and call into Hyper-V to transfer the data.
+ */
+static void hv_kmsg_dump(struct kmsg_dumper *dumper,
+			 enum kmsg_dump_reason reason)
+{
+	struct kmsg_dump_iter iter;
+	size_t bytes_written;
+
+	/* We are only interested in panics. */
+	if (reason != KMSG_DUMP_PANIC || !sysctl_record_panic_msg)
+		return;
+
+	/*
+	 * Write dump contents to the page. No need to synchronize; panic should
+	 * be single-threaded.
+	 */
+	kmsg_dump_rewind(&iter);
+	kmsg_dump_get_buffer(&iter, false, hv_panic_page, HV_HYP_PAGE_SIZE,
+			     &bytes_written);
+	if (!bytes_written)
+		return;
+	/*
+	 * P3 to contain the physical address of the panic page & P4 to
+	 * 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);
+
+	/*
+	 * 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));
+}
+
+static struct kmsg_dumper hv_kmsg_dumper = {
+	.dump = hv_kmsg_dump,
+};
+
+static void hv_kmsg_dump_unregister(void)
+{
+	kmsg_dump_unregister(&hv_kmsg_dumper);
+	unregister_die_notifier(&hyperv_die_report_block);
+	atomic_notifier_chain_unregister(&panic_notifier_list,
+					 &hyperv_panic_report_block);
+
+	hv_free_hyperv_page((unsigned long)hv_panic_page);
+	hv_panic_page = NULL;
+}
+
+static void hv_kmsg_dump_register(void)
+{
+	int ret;
+
+	hv_panic_page = hv_alloc_hyperv_zeroed_page();
+	if (!hv_panic_page) {
+		pr_err("Hyper-V: panic message page memory allocation failed\n");
+		return;
+	}
+
+	ret = kmsg_dump_register(&hv_kmsg_dumper);
+	if (ret) {
+		pr_err("Hyper-V: kmsg dump register error 0x%x\n", ret);
+		hv_free_hyperv_page((unsigned long)hv_panic_page);
+		hv_panic_page = NULL;
+	}
+}
+
 int __init hv_common_init(void)
 {
 	int i;
 
+	if (hv_is_isolation_supported())
+		sysctl_record_panic_msg = 0;
+
 	/*
 	 * Hyper-V expects to get crash register data or kmsg when
 	 * crash enlightment is available and system crashes. Set
@@ -84,8 +290,33 @@ int __init hv_common_init(void)
 	 * kernel.
 	 */
 	if (ms_hyperv.misc_features & HV_FEATURE_GUEST_CRASH_MSR_AVAILABLE) {
+		u64 hyperv_crash_ctl;
+
 		crash_kexec_post_notifiers = true;
 		pr_info("Hyper-V: enabling crash_kexec_post_notifiers\n");
+
+		/*
+		 * Panic message recording (sysctl_record_panic_msg)
+		 * is enabled by default in non-isolated guests and
+		 * disabled by default in isolated guests; the panic
+		 * message recording won't be available in isolated
+		 * guests should the following registration fail.
+		 */
+		hv_ctl_table_hdr = register_sysctl("kernel", hv_ctl_table);
+		if (!hv_ctl_table_hdr)
+			pr_err("Hyper-V: sysctl table register error");
+
+		/*
+		 * 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);
+		if (hyperv_crash_ctl & HV_CRASH_CTL_CRASH_NOTIFY_MSG)
+			hv_kmsg_dump_register();
+
+		register_die_notifier(&hyperv_die_report_block);
+		atomic_notifier_chain_register(&panic_notifier_list,
+					       &hyperv_panic_report_block);
 	}
 
 	/*
@@ -311,14 +542,3 @@ u64 __weak hv_ghcb_hypercall(u64 control, void *input, void *output, u32 input_s
 	return HV_STATUS_INVALID_PARAMETER;
 }
 EXPORT_SYMBOL_GPL(hv_ghcb_hypercall);
-
-void __weak *hv_map_memory(void *addr, unsigned long size)
-{
-	return NULL;
-}
-EXPORT_SYMBOL_GPL(hv_map_memory);
-
-void __weak hv_unmap_memory(void *addr)
-{
-}
-EXPORT_SYMBOL_GPL(hv_unmap_memory);

drivers/hv/hyperv_vmbus.h

@@ -122,10 +122,6 @@ enum {
 struct hv_per_cpu_context {
 	void *synic_message_page;
 	void *synic_event_page;
-	/*
-	 * buffer to post messages to the host.
-	 */
-	void *post_msg_page;
 
 	/*
 	 * Starting with win8, we can take channel interrupts on any CPU;
@@ -241,8 +237,6 @@ struct vmbus_connection {
 	 * is child->parent notification
 	 */
 	struct hv_monitor_page *monitor_pages[2];
-	void *monitor_pages_original[2];
-	phys_addr_t monitor_pages_pa[2];
 	struct list_head chn_msg_list;
 	spinlock_t channelmsg_lock;