arch/x86/include/asm/mshyperv.h

#ifndef _ASM_X86_MSHYPER_H
#define _ASM_X86_MSHYPER_H

#include <linux/types.h>
#include <linux/interrupt.h>
#include <asm/hyperv.h>

/*
 * The below CPUID leaves are present if VersionAndFeatures.HypervisorPresent
 * is set by CPUID(HVCPUID_VERSION_FEATURES).
 */
enum hv_cpuid_function {
	HVCPUID_VERSION_FEATURES		= 0x00000001,
	HVCPUID_VENDOR_MAXFUNCTION		= 0x40000000,
	HVCPUID_INTERFACE			= 0x40000001,

	/*
	 * The remaining functions depend on the value of
	 * HVCPUID_INTERFACE
	 */
	HVCPUID_VERSION				= 0x40000002,
	HVCPUID_FEATURES			= 0x40000003,
	HVCPUID_ENLIGHTENMENT_INFO		= 0x40000004,
	HVCPUID_IMPLEMENTATION_LIMITS		= 0x40000005,
};

struct ms_hyperv_info {
	u32 features;
	u32 misc_features;
	u32 hints;
};

extern struct ms_hyperv_info ms_hyperv;

/*
 * Declare the MSR used to setup pages used to communicate with the hypervisor.
 */
union hv_x64_msr_hypercall_contents {
	u64 as_uint64;
	struct {
		u64 enable:1;
		u64 reserved:11;
		u64 guest_physical_address:52;
	};
};

/*
 * TSC page layout.
 */

struct ms_hyperv_tsc_page {
	volatile u32 tsc_sequence;
	u32 reserved1;
	volatile u64 tsc_scale;
	volatile s64 tsc_offset;
	u64 reserved2[509];
};

/*
 * The guest OS needs to register the guest ID with the hypervisor.
 * The guest ID is a 64 bit entity and the structure of this ID is
 * specified in the Hyper-V specification:
 *
 * msdn.microsoft.com/en-us/library/windows/hardware/ff542653%28v=vs.85%29.aspx
 *
 * While the current guideline does not specify how Linux guest ID(s)
 * need to be generated, our plan is to publish the guidelines for
 * Linux and other guest operating systems that currently are hosted
 * on Hyper-V. The implementation here conforms to this yet
 * unpublished guidelines.
 *
 *
 * Bit(s)
 * 63 - Indicates if the OS is Open Source or not; 1 is Open Source
 * 62:56 - Os Type; Linux is 0x100
 * 55:48 - Distro specific identification
 * 47:16 - Linux kernel version number
 * 15:0  - Distro specific identification
 *
 *
 */

#define HV_LINUX_VENDOR_ID              0x8800

/*
 * Generate the guest ID based on the guideline described above.
 */

static inline  __u64 generate_guest_id(__u64 d_info1, __u64 kernel_version,
				       __u64 d_info2)
{
	__u64 guest_id = 0;

	guest_id = (((__u64)HV_LINUX_VENDOR_ID) << 56);
	guest_id |= (d_info1 << 48);
	guest_id |= (kernel_version << 16);
	guest_id |= d_info2;

	return guest_id;
}


/* Free the message slot and signal end-of-message if required */
static inline void vmbus_signal_eom(struct hv_message *msg, u32 old_msg_type)
{
	/*
	 * On crash we're reading some other CPU's message page and we need
	 * to be careful: this other CPU may already had cleared the header
	 * and the host may already had delivered some other message there.
	 * In case we blindly write msg->header.message_type we're going
	 * to lose it. We can still lose a message of the same type but
	 * we count on the fact that there can only be one
	 * CHANNELMSG_UNLOAD_RESPONSE and we don't care about other messages
	 * on crash.
	 */
	if (cmpxchg(&msg->header.message_type, old_msg_type,
		    HVMSG_NONE) != old_msg_type)
		return;

	/*
	 * Make sure the write to MessageType (ie set to
	 * HVMSG_NONE) happens before we read the
	 * MessagePending and EOMing. Otherwise, the EOMing
	 * will not deliver any more messages since there is
	 * no empty slot
	 */
	mb();

	if (msg->header.message_flags.msg_pending) {
		/*
		 * This will cause message queue rescan to
		 * possibly deliver another msg from the
		 * hypervisor
		 */
		wrmsrl(HV_X64_MSR_EOM, 0);
	}
}

#define hv_get_current_tick(tick) rdmsrl(HV_X64_MSR_TIME_REF_COUNT, tick)
#define hv_init_timer(timer, tick) wrmsrl(timer, tick)
#define hv_init_timer_config(config, val) wrmsrl(config, val)

#define hv_get_simp(val) rdmsrl(HV_X64_MSR_SIMP, val)
#define hv_set_simp(val) wrmsrl(HV_X64_MSR_SIMP, val)

#define hv_get_siefp(val) rdmsrl(HV_X64_MSR_SIEFP, val)
#define hv_set_siefp(val) wrmsrl(HV_X64_MSR_SIEFP, val)

void hyperv_callback_vector(void);
#ifdef CONFIG_TRACING
#define trace_hyperv_callback_vector hyperv_callback_vector
#endif
void hyperv_vector_handler(struct pt_regs *regs);
void hv_setup_vmbus_irq(void (*handler)(void));
void hv_remove_vmbus_irq(void);

void hv_setup_kexec_handler(void (*handler)(void));
void hv_remove_kexec_handler(void);
void hv_setup_crash_handler(void (*handler)(struct pt_regs *regs));
void hv_remove_crash_handler(void);

#if IS_ENABLED(CONFIG_HYPERV)
void hyperv_init(void);
void hyperv_report_panic(struct pt_regs *regs);
bool hv_is_hypercall_page_setup(void);
#endif
#endif