include/xen/interface/xen.h

/* SPDX-License-Identifier: MIT
 *
 * xen.h
 *
 * Guest OS interface to Xen.
 *
 * Copyright (c) 2004, K A Fraser
 */

#ifndef __XEN_PUBLIC_XEN_H__
#define __XEN_PUBLIC_XEN_H__

#include <xen/arm/interface.h>

/*
 * XEN "SYSTEM CALLS" (a.k.a. HYPERCALLS).
 */

/*
 * x86_32: EAX = vector; EBX, ECX, EDX, ESI, EDI = args 1, 2, 3, 4, 5.
 *         EAX = return value
 *         (argument registers may be clobbered on return)
 * x86_64: RAX = vector; RDI, RSI, RDX, R10, R8, R9 = args 1, 2, 3, 4, 5, 6.
 *         RAX = return value
 *         (argument registers not clobbered on return; RCX, R11 are)
 */
#define __HYPERVISOR_set_trap_table        0
#define __HYPERVISOR_mmu_update            1
#define __HYPERVISOR_set_gdt               2
#define __HYPERVISOR_stack_switch          3
#define __HYPERVISOR_set_callbacks         4
#define __HYPERVISOR_fpu_taskswitch        5
#define __HYPERVISOR_sched_op_compat       6
#define __HYPERVISOR_platform_op           7
#define __HYPERVISOR_set_debugreg          8
#define __HYPERVISOR_get_debugreg          9
#define __HYPERVISOR_update_descriptor    10
#define __HYPERVISOR_memory_op            12
#define __HYPERVISOR_multicall            13
#define __HYPERVISOR_update_va_mapping    14
#define __HYPERVISOR_set_timer_op         15
#define __HYPERVISOR_event_channel_op_compat 16
#define __HYPERVISOR_xen_version          17
#define __HYPERVISOR_console_io           18
#define __HYPERVISOR_physdev_op_compat    19
#define __HYPERVISOR_grant_table_op       20
#define __HYPERVISOR_vm_assist            21
#define __HYPERVISOR_update_va_mapping_otherdomain 22
#define __HYPERVISOR_iret                 23 /* x86 only */
#define __HYPERVISOR_vcpu_op              24
#define __HYPERVISOR_set_segment_base     25 /* x86/64 only */
#define __HYPERVISOR_mmuext_op            26
#define __HYPERVISOR_xsm_op               27
#define __HYPERVISOR_nmi_op               28
#define __HYPERVISOR_sched_op             29
#define __HYPERVISOR_callback_op          30
#define __HYPERVISOR_xenoprof_op          31
#define __HYPERVISOR_event_channel_op     32
#define __HYPERVISOR_physdev_op           33
#define __HYPERVISOR_hvm_op               34
#define __HYPERVISOR_sysctl               35
#define __HYPERVISOR_domctl               36
#define __HYPERVISOR_kexec_op             37
#define __HYPERVISOR_tmem_op              38
#define __HYPERVISOR_xc_reserved_op       39 /* reserved for XenClient */
#define __HYPERVISOR_xenpmu_op            40
#define __HYPERVISOR_dm_op                41

/* Architecture-specific hypercall definitions. */
#define __HYPERVISOR_arch_0               48
#define __HYPERVISOR_arch_1               49
#define __HYPERVISOR_arch_2               50
#define __HYPERVISOR_arch_3               51
#define __HYPERVISOR_arch_4               52
#define __HYPERVISOR_arch_5               53
#define __HYPERVISOR_arch_6               54
#define __HYPERVISOR_arch_7               55

#ifndef __ASSEMBLY__

typedef u16 domid_t;

/* Domain ids >= DOMID_FIRST_RESERVED cannot be used for ordinary domains. */
#define DOMID_FIRST_RESERVED (0x7FF0U)

/* DOMID_SELF is used in certain contexts to refer to oneself. */
#define DOMID_SELF (0x7FF0U)

/*
 * DOMID_IO is used to restrict page-table updates to mapping I/O memory.
 * Although no Foreign Domain need be specified to map I/O pages, DOMID_IO
 * is useful to ensure that no mappings to the OS's own heap are accidentally
 * installed. (e.g., in Linux this could cause havoc as reference counts
 * aren't adjusted on the I/O-mapping code path).
 * This only makes sense in MMUEXT_SET_FOREIGNDOM, but in that context can
 * be specified by any calling domain.
 */
#define DOMID_IO   (0x7FF1U)

/*
 * DOMID_XEN is used to allow privileged domains to map restricted parts of
 * Xen's heap space (e.g., the machine_to_phys table).
 * This only makes sense in MMUEXT_SET_FOREIGNDOM, and is only permitted if
 * the caller is privileged.
 */
#define DOMID_XEN  (0x7FF2U)

/* DOMID_COW is used as the owner of sharable pages */
#define DOMID_COW  (0x7FF3U)

/* DOMID_INVALID is used to identify pages with unknown owner. */
#define DOMID_INVALID (0x7FF4U)

/* Idle domain. */
#define DOMID_IDLE (0x7FFFU)

struct vcpu_info {
	/*
	 * 'evtchn_upcall_pending' is written non-zero by Xen to indicate
	 * a pending notification for a particular VCPU. It is then cleared
	 * by the guest OS /before/ checking for pending work, thus avoiding
	 * a set-and-check race. Note that the mask is only accessed by Xen
	 * on the CPU that is currently hosting the VCPU. This means that the
	 * pending and mask flags can be updated by the guest without special
	 * synchronisation (i.e., no need for the x86 LOCK prefix).
	 * This may seem suboptimal because if the pending flag is set by
	 * a different CPU then an IPI may be scheduled even when the mask
	 * is set. However, note:
	 *  1. The task of 'interrupt holdoff' is covered by the per-event-
	 *     channel mask bits. A 'noisy' event that is continually being
	 *     triggered can be masked at source at this very precise
	 *     granularity.
	 *  2. The main purpose of the per-VCPU mask is therefore to restrict
	 *     reentrant execution: whether for concurrency control, or to
	 *     prevent unbounded stack usage. Whatever the purpose, we expect
	 *     that the mask will be asserted only for short periods at a time,
	 *     and so the likelihood of a 'spurious' IPI is suitably small.
	 * The mask is read before making an event upcall to the guest: a
	 * non-zero mask therefore guarantees that the VCPU will not receive
	 * an upcall activation. The mask is cleared when the VCPU requests
	 * to block: this avoids wakeup-waiting races.
	 */
	u8 evtchn_upcall_pending;
	u8 evtchn_upcall_mask;
	xen_ulong_t evtchn_pending_sel;
	struct arch_vcpu_info arch;
	struct pvclock_vcpu_time_info time;
}; /* 64 bytes (x86) */

/*
 * Xen/kernel shared data -- pointer provided in start_info.
 * NB. We expect that this struct is smaller than a page.
 */
struct shared_info {
	struct vcpu_info vcpu_info[MAX_VIRT_CPUS];

	/*
	 * A domain can create "event channels" on which it can send and receive
	 * asynchronous event notifications. There are three classes of event that
	 * are delivered by this mechanism:
	 *  1. Bi-directional inter- and intra-domain connections. Domains must
	 *     arrange out-of-band to set up a connection (usually by allocating
	 *     an unbound 'listener' port and avertising that via a storage service
	 *     such as xenstore).
	 *  2. Physical interrupts. A domain with suitable hardware-access
	 *     privileges can bind an event-channel port to a physical interrupt
	 *     source.
	 *  3. Virtual interrupts ('events'). A domain can bind an event-channel
	 *     port to a virtual interrupt source, such as the virtual-timer
	 *     device or the emergency console.
	 *
	 * Event channels are addressed by a "port index". Each channel is
	 * associated with two bits of information:
	 *  1. PENDING -- notifies the domain that there is a pending notification
	 *     to be processed. This bit is cleared by the guest.
	 *  2. MASK -- if this bit is clear then a 0->1 transition of PENDING
	 *     will cause an asynchronous upcall to be scheduled. This bit is only
	 *     updated by the guest. It is read-only within Xen. If a channel
	 *     becomes pending while the channel is masked then the 'edge' is lost
	 *     (i.e., when the channel is unmasked, the guest must manually handle
	 *     pending notifications as no upcall will be scheduled by Xen).
	 *
	 * To expedite scanning of pending notifications, any 0->1 pending
	 * transition on an unmasked channel causes a corresponding bit in a
	 * per-vcpu selector word to be set. Each bit in the selector covers a
	 * 'C long' in the PENDING bitfield array.
	 */
	xen_ulong_t evtchn_pending[sizeof(xen_ulong_t) * 8];
	xen_ulong_t evtchn_mask[sizeof(xen_ulong_t) * 8];

	/*
	 * Wallclock time: updated only by control software. Guests should base
	 * their gettimeofday() syscall on this wallclock-base value.
	 */
	struct pvclock_wall_clock wc;

	struct arch_shared_info arch;

};

#else /* __ASSEMBLY__ */

/* In assembly code we cannot use C numeric constant suffixes. */
#define mk_unsigned_long(x) x

#endif /* !__ASSEMBLY__ */

#endif /* __XEN_PUBLIC_XEN_H__ */