1 files changed, 795 insertions, 1 deletions

diff --git a/drivers/hv/hv_common.c b/drivers/hv/hv_common.c
index 7f42da98d377..0a3ab7efed46 100644
--- a/drivers/hv/hv_common.c
+++ b/drivers/hv/hv_common.c
@@ -13,11 +13,559 @@
  */
 
 #include <linux/types.h>
+#include <linux/acpi.h>
 #include <linux/export.h>
 #include <linux/bitfield.h>
-#include <asm/hyperv-tlfs.h>
+#include <linux/cpumask.h>
+#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>
+#include <hyperv/hvhdk.h>
 #include <asm/mshyperv.h>
 
+u64 hv_current_partition_id = HV_PARTITION_ID_SELF;
+EXPORT_SYMBOL_GPL(hv_current_partition_id);
+
+enum hv_partition_type hv_curr_partition_type;
+EXPORT_SYMBOL_GPL(hv_curr_partition_type);
+
+/*
+ * ms_hyperv and hv_nested are defined here with other
+ * Hyper-V specific globals so they are shared across all architectures and are
+ * built only when CONFIG_HYPERV is defined.  But on x86,
+ * ms_hyperv_init_platform() is built even when CONFIG_HYPERV is not
+ * defined, and it uses these three variables.  So mark them as __weak
+ * here, allowing for an overriding definition in the module containing
+ * ms_hyperv_init_platform().
+ */
+bool __weak hv_nested;
+EXPORT_SYMBOL_GPL(hv_nested);
+
+struct ms_hyperv_info __weak ms_hyperv;
+EXPORT_SYMBOL_GPL(ms_hyperv);
+
+u32 *hv_vp_index;
+EXPORT_SYMBOL_GPL(hv_vp_index);
+
+u32 hv_max_vp_index;
+EXPORT_SYMBOL_GPL(hv_max_vp_index);
+
+void * __percpu *hyperv_pcpu_input_arg;
+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;
+
+/*
+ * Per-cpu array holding the tail pointer for the SynIC event ring buffer
+ * for each SINT.
+ *
+ * We cannot maintain this in mshv driver because the tail pointer should
+ * persist even if the mshv driver is unloaded.
+ */
+u8 * __percpu *hv_synic_eventring_tail;
+EXPORT_SYMBOL_GPL(hv_synic_eventring_tail);
+
+/*
+ * Hyper-V specific initialization and shutdown code that is
+ * common across all architectures.  Called from architecture
+ * specific initialization functions.
+ */
+
+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;
+
+	free_percpu(hyperv_pcpu_output_arg);
+	hyperv_pcpu_output_arg = NULL;
+
+	free_percpu(hyperv_pcpu_input_arg);
+	hyperv_pcpu_input_arg = NULL;
+
+	free_percpu(hv_synic_eventring_tail);
+	hv_synic_eventring_tail = NULL;
+}
+
+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 const 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,
+			 struct kmsg_dump_detail *detail)
+{
+	struct kmsg_dump_iter iter;
+	size_t bytes_written;
+
+	/* We are only interested in panics. */
+	if (detail->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_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_msr(HV_MSR_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);
+
+	kfree(hv_panic_page);
+	hv_panic_page = NULL;
+}
+
+static void hv_kmsg_dump_register(void)
+{
+	int ret;
+
+	hv_panic_page = kzalloc(HV_HYP_PAGE_SIZE, GFP_KERNEL);
+	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);
+		kfree(hv_panic_page);
+		hv_panic_page = NULL;
+	}
+}
+
+static inline bool hv_output_page_exists(void)
+{
+	return hv_parent_partition() || IS_ENABLED(CONFIG_HYPERV_VTL_MODE);
+}
+
+void __init hv_get_partition_id(void)
+{
+	struct hv_output_get_partition_id *output;
+	unsigned long flags;
+	u64 status, pt_id;
+
+	local_irq_save(flags);
+	output = *this_cpu_ptr(hyperv_pcpu_input_arg);
+	status = hv_do_hypercall(HVCALL_GET_PARTITION_ID, NULL, output);
+	pt_id = output->partition_id;
+	local_irq_restore(flags);
+
+	if (hv_result_success(status))
+		hv_current_partition_id = pt_id;
+	else
+		pr_err("Hyper-V: failed to get partition ID: %#x\n",
+		       hv_result(status));
+}
+#if IS_ENABLED(CONFIG_HYPERV_VTL_MODE)
+u8 __init get_vtl(void)
+{
+	u64 control = HV_HYPERCALL_REP_COMP_1 | HVCALL_GET_VP_REGISTERS;
+	struct hv_input_get_vp_registers *input;
+	struct hv_output_get_vp_registers *output;
+	unsigned long flags;
+	u64 ret;
+
+	local_irq_save(flags);
+	input = *this_cpu_ptr(hyperv_pcpu_input_arg);
+	output = *this_cpu_ptr(hyperv_pcpu_output_arg);
+
+	memset(input, 0, struct_size(input, names, 1));
+	input->partition_id = HV_PARTITION_ID_SELF;
+	input->vp_index = HV_VP_INDEX_SELF;
+	input->input_vtl.as_uint8 = 0;
+	input->names[0] = HV_REGISTER_VSM_VP_STATUS;
+
+	ret = hv_do_hypercall(control, input, output);
+	if (hv_result_success(ret)) {
+		ret = output->values[0].reg8 & HV_VTL_MASK;
+	} else {
+		pr_err("Failed to get VTL(error: %lld) exiting...\n", ret);
+		BUG();
+	}
+
+	local_irq_restore(flags);
+	return ret;
+}
+#endif
+
+int __init hv_common_init(void)
+{
+	int i;
+	union hv_hypervisor_version_info version;
+
+	/* Get information about the Microsoft Hypervisor version */
+	if (!hv_get_hypervisor_version(&version))
+		pr_info("Hyper-V: Hypervisor 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;
+
+	/*
+	 * Hyper-V expects to get crash register data or kmsg when
+	 * crash enlightment is available and system crashes. Set
+	 * crash_kexec_post_notifiers to be true to make sure that
+	 * calling crash enlightment interface before running kdump
+	 * 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_msr(HV_MSR_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);
+	}
+
+	/*
+	 * Allocate the per-CPU state for the hypercall input arg.
+	 * If this allocation fails, we will not be able to setup
+	 * (per-CPU) hypercall input page and thus this failure is
+	 * fatal on Hyper-V.
+	 */
+	hyperv_pcpu_input_arg = alloc_percpu(void  *);
+	BUG_ON(!hyperv_pcpu_input_arg);
+
+	/* Allocate the per-CPU state for output arg for root */
+	if (hv_output_page_exists()) {
+		hyperv_pcpu_output_arg = alloc_percpu(void *);
+		BUG_ON(!hyperv_pcpu_output_arg);
+	}
+
+	if (hv_parent_partition()) {
+		hv_synic_eventring_tail = alloc_percpu(u8 *);
+		BUG_ON(!hv_synic_eventring_tail);
+	}
+
+	hv_vp_index = kmalloc_array(nr_cpu_ids, sizeof(*hv_vp_index),
+				    GFP_KERNEL);
+	if (!hv_vp_index) {
+		hv_common_free();
+		return -ENOMEM;
+	}
+
+	for (i = 0; i < nr_cpu_ids; i++)
+		hv_vp_index[i] = VP_INVAL;
+
+	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.
+ * Called by the CPU hotplug mechanism.
+ */
+
+int hv_common_cpu_init(unsigned int cpu)
+{
+	void **inputarg, **outputarg;
+	u8 **synic_eventring_tail;
+	u64 msr_vp_index;
+	gfp_t flags;
+	const int pgcount = hv_output_page_exists() ? 2 : 1;
+	void *mem;
+	int ret = 0;
+
+	/* hv_cpu_init() can be called with IRQs disabled from hv_resume() */
+	flags = irqs_disabled() ? GFP_ATOMIC : GFP_KERNEL;
+
+	inputarg = (void **)this_cpu_ptr(hyperv_pcpu_input_arg);
+
+	/*
+	 * The per-cpu memory is already allocated if this CPU was previously
+	 * online and then taken offline
+	 */
+	if (!*inputarg) {
+		mem = kmalloc_array(pgcount, HV_HYP_PAGE_SIZE, flags);
+		if (!mem)
+			return -ENOMEM;
+
+		if (hv_output_page_exists()) {
+			outputarg = (void **)this_cpu_ptr(hyperv_pcpu_output_arg);
+			*outputarg = (char *)mem + HV_HYP_PAGE_SIZE;
+		}
+
+		if (!ms_hyperv.paravisor_present &&
+		    (hv_isolation_type_snp() || hv_isolation_type_tdx())) {
+			ret = set_memory_decrypted((unsigned long)mem, pgcount);
+			if (ret) {
+				/* It may be unsafe to free 'mem' */
+				return ret;
+			}
+
+			memset(mem, 0x00, pgcount * HV_HYP_PAGE_SIZE);
+		}
+
+		/*
+		 * In a fully enlightened TDX/SNP VM with more than 64 VPs, if
+		 * hyperv_pcpu_input_arg is not NULL, set_memory_decrypted() ->
+		 * ... -> cpa_flush()-> ... -> __send_ipi_mask_ex() tries to
+		 * use hyperv_pcpu_input_arg as the hypercall input page, which
+		 * must be a decrypted page in such a VM, but the page is still
+		 * encrypted before set_memory_decrypted() returns. Fix this by
+		 * setting *inputarg after the above set_memory_decrypted(): if
+		 * hyperv_pcpu_input_arg is NULL, __send_ipi_mask_ex() returns
+		 * HV_STATUS_INVALID_PARAMETER immediately, and the function
+		 * hv_send_ipi_mask() falls back to orig_apic.send_IPI_mask(),
+		 * which may be slightly slower than the hypercall, but still
+		 * works correctly in such a VM.
+		 */
+		*inputarg = mem;
+	}
+
+	msr_vp_index = hv_get_msr(HV_MSR_VP_INDEX);
+
+	hv_vp_index[cpu] = msr_vp_index;
+
+	if (msr_vp_index > hv_max_vp_index)
+		hv_max_vp_index = msr_vp_index;
+
+	if (hv_parent_partition()) {
+		synic_eventring_tail = (u8 **)this_cpu_ptr(hv_synic_eventring_tail);
+		*synic_eventring_tail = kcalloc(HV_SYNIC_SINT_COUNT,
+						sizeof(u8), flags);
+		/* No need to unwind any of the above on failure here */
+		if (unlikely(!*synic_eventring_tail))
+			ret = -ENOMEM;
+	}
+
+	return ret;
+}
+
+int hv_common_cpu_die(unsigned int cpu)
+{
+	u8 **synic_eventring_tail;
+	/*
+	 * The hyperv_pcpu_input_arg and hyperv_pcpu_output_arg memory
+	 * is not freed when the CPU goes offline as the hyperv_pcpu_input_arg
+	 * may be used by the Hyper-V vPCI driver in reassigning interrupts
+	 * as part of the offlining process.  The interrupt reassignment
+	 * happens *after* the CPUHP_AP_HYPERV_ONLINE state has run and
+	 * called this function.
+	 *
+	 * If a previously offlined CPU is brought back online again, the
+	 * originally allocated memory is reused in hv_common_cpu_init().
+	 */
+
+	if (hv_parent_partition()) {
+		synic_eventring_tail = this_cpu_ptr(hv_synic_eventring_tail);
+		kfree(*synic_eventring_tail);
+		*synic_eventring_tail = NULL;
+	}
+
+	return 0;
+}
 
 /* Bit mask of the extended capability to query: see HV_EXT_CAPABILITY_xxx */
 bool hv_query_ext_cap(u64 cap_query)
@@ -64,3 +612,249 @@ bool hv_query_ext_cap(u64 cap_query)
 	return hv_extended_cap & cap_query;
 }
 EXPORT_SYMBOL_GPL(hv_query_ext_cap);
+
+void hv_setup_dma_ops(struct device *dev, bool coherent)
+{
+	arch_setup_dma_ops(dev, coherent);
+}
+EXPORT_SYMBOL_GPL(hv_setup_dma_ops);
+
+bool hv_is_hibernation_supported(void)
+{
+	return !hv_root_partition() && acpi_sleep_state_supported(ACPI_STATE_S4);
+}
+EXPORT_SYMBOL_GPL(hv_is_hibernation_supported);
+
+/*
+ * Default function to read the Hyper-V reference counter, independent
+ * of whether Hyper-V enlightened clocks/timers are being used. But on
+ * architectures where it is used, Hyper-V enlightenment code in
+ * hyperv_timer.c may override this function.
+ */
+static u64 __hv_read_ref_counter(void)
+{
+	return hv_get_msr(HV_MSR_TIME_REF_COUNT);
+}
+
+u64 (*hv_read_reference_counter)(void) = __hv_read_ref_counter;
+EXPORT_SYMBOL_GPL(hv_read_reference_counter);
+
+/* These __weak functions provide default "no-op" behavior and
+ * may be overridden by architecture specific versions. Architectures
+ * for which the default "no-op" behavior is sufficient can leave
+ * them unimplemented and not be cluttered with a bunch of stub
+ * functions in arch-specific code.
+ */
+
+bool __weak hv_is_isolation_supported(void)
+{
+	return false;
+}
+EXPORT_SYMBOL_GPL(hv_is_isolation_supported);
+
+bool __weak hv_isolation_type_snp(void)
+{
+	return false;
+}
+EXPORT_SYMBOL_GPL(hv_isolation_type_snp);
+
+bool __weak hv_isolation_type_tdx(void)
+{
+	return false;
+}
+EXPORT_SYMBOL_GPL(hv_isolation_type_tdx);
+
+void __weak hv_setup_vmbus_handler(void (*handler)(void))
+{
+}
+EXPORT_SYMBOL_GPL(hv_setup_vmbus_handler);
+
+void __weak hv_remove_vmbus_handler(void)
+{
+}
+EXPORT_SYMBOL_GPL(hv_remove_vmbus_handler);
+
+void __weak hv_setup_mshv_handler(void (*handler)(void))
+{
+}
+EXPORT_SYMBOL_GPL(hv_setup_mshv_handler);
+
+void __weak hv_setup_kexec_handler(void (*handler)(void))
+{
+}
+EXPORT_SYMBOL_GPL(hv_setup_kexec_handler);
+
+void __weak hv_remove_kexec_handler(void)
+{
+}
+EXPORT_SYMBOL_GPL(hv_remove_kexec_handler);
+
+void __weak hv_setup_crash_handler(void (*handler)(struct pt_regs *regs))
+{
+}
+EXPORT_SYMBOL_GPL(hv_setup_crash_handler);
+
+void __weak hv_remove_crash_handler(void)
+{
+}
+EXPORT_SYMBOL_GPL(hv_remove_crash_handler);
+
+void __weak hyperv_cleanup(void)
+{
+}
+EXPORT_SYMBOL_GPL(hyperv_cleanup);
+
+u64 __weak hv_ghcb_hypercall(u64 control, void *input, void *output, u32 input_size)
+{
+	return HV_STATUS_INVALID_PARAMETER;
+}
+EXPORT_SYMBOL_GPL(hv_ghcb_hypercall);
+
+u64 __weak hv_tdx_hypercall(u64 control, u64 param1, u64 param2)
+{
+	return HV_STATUS_INVALID_PARAMETER;
+}
+EXPORT_SYMBOL_GPL(hv_tdx_hypercall);
+
+void __weak hv_enable_coco_interrupt(unsigned int cpu, unsigned int vector, bool set)
+{
+}
+EXPORT_SYMBOL_GPL(hv_enable_coco_interrupt);
+
+void __weak hv_para_set_sint_proxy(bool enable)
+{
+}
+EXPORT_SYMBOL_GPL(hv_para_set_sint_proxy);
+
+u64 __weak hv_para_get_synic_register(unsigned int reg)
+{
+	return ~0ULL;
+}
+EXPORT_SYMBOL_GPL(hv_para_get_synic_register);
+
+void __weak hv_para_set_synic_register(unsigned int reg, u64 val)
+{
+}
+EXPORT_SYMBOL_GPL(hv_para_set_synic_register);
+
+void hv_identify_partition_type(void)
+{
+	/* Assume guest role */
+	hv_curr_partition_type = HV_PARTITION_TYPE_GUEST;
+	/*
+	 * Check partition creation and cpu management privileges
+	 *
+	 * Hyper-V should never specify running as root and as a Confidential
+	 * VM. But to protect against a compromised/malicious Hyper-V trying
+	 * to exploit root behavior to expose Confidential VM memory, ignore
+	 * the root partition setting if also a Confidential VM.
+	 */
+	if ((ms_hyperv.priv_high & HV_CREATE_PARTITIONS) &&
+	    !(ms_hyperv.priv_high & HV_ISOLATION)) {
+
+		if (!IS_ENABLED(CONFIG_MSHV_ROOT)) {
+			pr_crit("Hyper-V: CONFIG_MSHV_ROOT not enabled!\n");
+		} else if (ms_hyperv.priv_high & HV_CPU_MANAGEMENT) {
+			pr_info("Hyper-V: running as root partition\n");
+			hv_curr_partition_type = HV_PARTITION_TYPE_ROOT;
+		} else {
+			pr_info("Hyper-V: running as L1VH partition\n");
+			hv_curr_partition_type = HV_PARTITION_TYPE_L1VH;
+		}
+	}
+}
+
+struct hv_status_info {
+	char *string;
+	int errno;
+	u16 code;
+};
+
+/*
+ * Note on the errno mappings:
+ * A failed hypercall is usually only recoverable (or loggable) near
+ * the call site where the HV_STATUS_* code is known. So the errno
+ * it gets converted to is not too useful further up the stack.
+ * Provide a few mappings that could be useful, and revert to -EIO
+ * as a fallback.
+ */
+static const struct hv_status_info hv_status_infos[] = {
+#define _STATUS_INFO(status, errno) { #status, (errno), (status) }
+	_STATUS_INFO(HV_STATUS_SUCCESS,				0),
+	_STATUS_INFO(HV_STATUS_INVALID_HYPERCALL_CODE,		-EINVAL),
+	_STATUS_INFO(HV_STATUS_INVALID_HYPERCALL_INPUT,		-EINVAL),
+	_STATUS_INFO(HV_STATUS_INVALID_ALIGNMENT,		-EIO),
+	_STATUS_INFO(HV_STATUS_INVALID_PARAMETER,		-EINVAL),
+	_STATUS_INFO(HV_STATUS_ACCESS_DENIED,			-EIO),
+	_STATUS_INFO(HV_STATUS_INVALID_PARTITION_STATE,		-EIO),
+	_STATUS_INFO(HV_STATUS_OPERATION_DENIED,		-EIO),
+	_STATUS_INFO(HV_STATUS_UNKNOWN_PROPERTY,		-EIO),
+	_STATUS_INFO(HV_STATUS_PROPERTY_VALUE_OUT_OF_RANGE,	-EIO),
+	_STATUS_INFO(HV_STATUS_INSUFFICIENT_MEMORY,		-ENOMEM),
+	_STATUS_INFO(HV_STATUS_INVALID_PARTITION_ID,		-EINVAL),
+	_STATUS_INFO(HV_STATUS_INVALID_VP_INDEX,		-EINVAL),
+	_STATUS_INFO(HV_STATUS_NOT_FOUND,			-EIO),
+	_STATUS_INFO(HV_STATUS_INVALID_PORT_ID,			-EINVAL),
+	_STATUS_INFO(HV_STATUS_INVALID_CONNECTION_ID,		-EINVAL),
+	_STATUS_INFO(HV_STATUS_INSUFFICIENT_BUFFERS,		-EIO),
+	_STATUS_INFO(HV_STATUS_NOT_ACKNOWLEDGED,		-EIO),
+	_STATUS_INFO(HV_STATUS_INVALID_VP_STATE,		-EIO),
+	_STATUS_INFO(HV_STATUS_NO_RESOURCES,			-EIO),
+	_STATUS_INFO(HV_STATUS_PROCESSOR_FEATURE_NOT_SUPPORTED,	-EIO),
+	_STATUS_INFO(HV_STATUS_INVALID_LP_INDEX,		-EINVAL),
+	_STATUS_INFO(HV_STATUS_INVALID_REGISTER_VALUE,		-EINVAL),
+	_STATUS_INFO(HV_STATUS_INVALID_LP_INDEX,		-EIO),
+	_STATUS_INFO(HV_STATUS_INVALID_REGISTER_VALUE,		-EIO),
+	_STATUS_INFO(HV_STATUS_OPERATION_FAILED,		-EIO),
+	_STATUS_INFO(HV_STATUS_TIME_OUT,			-EIO),
+	_STATUS_INFO(HV_STATUS_CALL_PENDING,			-EIO),
+	_STATUS_INFO(HV_STATUS_VTL_ALREADY_ENABLED,		-EIO),
+#undef _STATUS_INFO
+};
+
+static inline const struct hv_status_info *find_hv_status_info(u64 hv_status)
+{
+	int i;
+	u16 code = hv_result(hv_status);
+
+	for (i = 0; i < ARRAY_SIZE(hv_status_infos); ++i) {
+		const struct hv_status_info *info = &hv_status_infos[i];
+
+		if (info->code == code)
+			return info;
+	}
+
+	return NULL;
+}
+
+/* Convert a hypercall result into a linux-friendly error code. */
+int hv_result_to_errno(u64 status)
+{
+	const struct hv_status_info *info;
+
+	/* hv_do_hypercall() may return U64_MAX, hypercalls aren't possible */
+	if (unlikely(status == U64_MAX))
+		return -EOPNOTSUPP;
+
+	info = find_hv_status_info(status);
+	if (info)
+		return info->errno;
+
+	return -EIO;
+}
+EXPORT_SYMBOL_GPL(hv_result_to_errno);
+
+const char *hv_result_to_string(u64 status)
+{
+	const struct hv_status_info *info;
+
+	if (unlikely(status == U64_MAX))
+		return "Hypercall page missing!";
+
+	info = find_hv_status_info(status);
+	if (info)
+		return info->string;
+
+	return "Unknown";
+}
+EXPORT_SYMBOL_GPL(hv_result_to_string);