FreeBSD/Linux Kernel Cross Reference
sys/xen/interface/xen.h

     /******************************************************************************
      * xen.h
      *
      * Guest OS interface to Xen.
      *
      * Permission is hereby granted, free of charge, to any person obtaining a copy
      * of this software and associated documentation files (the "Software"), to
      * deal in the Software without restriction, including without limitation the
      * rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
     * sell copies of the Software, and to permit persons to whom the Software is
     * furnished to do so, subject to the following conditions:
     *
     * The above copyright notice and this permission notice shall be included in
     * all copies or substantial portions of the Software.
     *
     * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
     * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
     * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
     * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
     * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
     * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
     * DEALINGS IN THE SOFTWARE.
     *
     * Copyright (c) 2004, K A Fraser
     */
    
    #ifndef __XEN_PUBLIC_XEN_H__
    #define __XEN_PUBLIC_XEN_H__
    
    #include "xen-compat.h"
    
    #if defined(__i386__) || defined(__x86_64__)
    #include "arch-x86/xen.h"
    #elif defined(__arm__) || defined (__aarch64__)
    #include "arch-arm.h"
    #else
    #error "Unsupported architecture"
    #endif
    
    #ifndef __ASSEMBLY__
    /* Guest handles for primitive C types. */
    DEFINE_XEN_GUEST_HANDLE(char);
    __DEFINE_XEN_GUEST_HANDLE(uchar, unsigned char);
    DEFINE_XEN_GUEST_HANDLE(int);
    __DEFINE_XEN_GUEST_HANDLE(uint,  unsigned int);
    #if __XEN_INTERFACE_VERSION__ < 0x00040300
    DEFINE_XEN_GUEST_HANDLE(long);
    __DEFINE_XEN_GUEST_HANDLE(ulong, unsigned long);
    #endif
    DEFINE_XEN_GUEST_HANDLE(void);
    
    DEFINE_XEN_GUEST_HANDLE(uint64_t);
    DEFINE_XEN_GUEST_HANDLE(xen_pfn_t);
    DEFINE_XEN_GUEST_HANDLE(xen_ulong_t);
    
    /* Define a variable length array (depends on compiler). */
    #if defined(__STDC_VERSION__) && __STDC_VERSION__ >= 199901L
    #define XEN_FLEX_ARRAY_DIM
    #elif defined(__GNUC__)
    #define XEN_FLEX_ARRAY_DIM  0
    #else
    #define XEN_FLEX_ARRAY_DIM  1 /* variable size */
    #endif
    
    /* Turn a plain number into a C unsigned (long (long)) constant. */
    #define __xen_mk_uint(x)  x ## U
    #define __xen_mk_ulong(x) x ## UL
    #ifndef __xen_mk_ullong
    # define __xen_mk_ullong(x) x ## ULL
    #endif
    #define xen_mk_uint(x)    __xen_mk_uint(x)
    #define xen_mk_ulong(x)   __xen_mk_ulong(x)
    #define xen_mk_ullong(x)  __xen_mk_ullong(x)
    
    #else
    
    /* In assembly code we cannot use C numeric constant suffixes. */
    #define xen_mk_uint(x)   x
    #define xen_mk_ulong(x)  x
    #define xen_mk_ullong(x) x
    
    #endif
    
    /*
     * HYPERCALLS
     */
    
    /* `incontents 100 hcalls List of hypercalls
     * ` enum hypercall_num { // __HYPERVISOR_* => HYPERVISOR_*()
     */
    
    #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 /* compat since 0x00030101 */
    #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 /* compat since 0x00030202 */
   #define __HYPERVISOR_xen_version          17
   #define __HYPERVISOR_console_io           18
   #define __HYPERVISOR_physdev_op_compat    19 /* compat since 0x00030202 */
   #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_argo_op              39
   #define __HYPERVISOR_xenpmu_op            40
   #define __HYPERVISOR_dm_op                41
   #define __HYPERVISOR_hypfs_op             42
   
   /* 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
   
   /* ` } */
   
   /*
    * HYPERCALL COMPATIBILITY.
    */
   
   /* New sched_op hypercall introduced in 0x00030101. */
   #if __XEN_INTERFACE_VERSION__ < 0x00030101
   #undef __HYPERVISOR_sched_op
   #define __HYPERVISOR_sched_op __HYPERVISOR_sched_op_compat
   #endif
   
   /* New event-channel and physdev hypercalls introduced in 0x00030202. */
   #if __XEN_INTERFACE_VERSION__ < 0x00030202
   #undef __HYPERVISOR_event_channel_op
   #define __HYPERVISOR_event_channel_op __HYPERVISOR_event_channel_op_compat
   #undef __HYPERVISOR_physdev_op
   #define __HYPERVISOR_physdev_op __HYPERVISOR_physdev_op_compat
   #endif
   
   /* New platform_op hypercall introduced in 0x00030204. */
   #if __XEN_INTERFACE_VERSION__ < 0x00030204
   #define __HYPERVISOR_dom0_op __HYPERVISOR_platform_op
   #endif
   
   /*
    * VIRTUAL INTERRUPTS
    *
    * Virtual interrupts that a guest OS may receive from Xen.
    *
    * In the side comments, 'V.' denotes a per-VCPU VIRQ while 'G.' denotes a
    * global VIRQ. The former can be bound once per VCPU and cannot be re-bound.
    * The latter can be allocated only once per guest: they must initially be
    * allocated to VCPU0 but can subsequently be re-bound.
    */
   /* ` enum virq { */
   #define VIRQ_TIMER      0  /* V. Timebase update, and/or requested timeout.  */
   #define VIRQ_DEBUG      1  /* V. Request guest to dump debug info.           */
   #define VIRQ_CONSOLE    2  /* G. (DOM0) Bytes received on emergency console. */
   #define VIRQ_DOM_EXC    3  /* G. (DOM0) Exceptional event for some domain.   */
   #define VIRQ_TBUF       4  /* G. (DOM0) Trace buffer has records available.  */
   #define VIRQ_DEBUGGER   6  /* G. (DOM0) A domain has paused for debugging.   */
   #define VIRQ_XENOPROF   7  /* V. XenOprofile interrupt: new sample available */
   #define VIRQ_CON_RING   8  /* G. (DOM0) Bytes received on console            */
   #define VIRQ_PCPU_STATE 9  /* G. (DOM0) PCPU state changed                   */
   #define VIRQ_MEM_EVENT  10 /* G. (DOM0) A memory event has occurred          */
   #define VIRQ_ARGO       11 /* G. Argo interdomain message notification       */
   #define VIRQ_ENOMEM     12 /* G. (DOM0) Low on heap memory       */
   #define VIRQ_XENPMU     13 /* V.  PMC interrupt                              */
   
   /* Architecture-specific VIRQ definitions. */
   #define VIRQ_ARCH_0    16
   #define VIRQ_ARCH_1    17
   #define VIRQ_ARCH_2    18
   #define VIRQ_ARCH_3    19
   #define VIRQ_ARCH_4    20
   #define VIRQ_ARCH_5    21
   #define VIRQ_ARCH_6    22
   #define VIRQ_ARCH_7    23
   /* ` } */
   
   #define NR_VIRQS       24
   
   /*
    * ` enum neg_errnoval
    * ` HYPERVISOR_mmu_update(const struct mmu_update reqs[],
    * `                       unsigned count, unsigned *done_out,
    * `                       unsigned foreigndom)
    * `
    * @reqs is an array of mmu_update_t structures ((ptr, val) pairs).
    * @count is the length of the above array.
    * @pdone is an output parameter indicating number of completed operations
    * @foreigndom[15:0]: FD, the expected owner of data pages referenced in this
    *                    hypercall invocation. Can be DOMID_SELF.
    * @foreigndom[31:16]: PFD, the expected owner of pagetable pages referenced
    *                     in this hypercall invocation. The value of this field
    *                     (x) encodes the PFD as follows:
    *                     x == 0 => PFD == DOMID_SELF
    *                     x != 0 => PFD == x - 1
    *
    * Sub-commands: ptr[1:0] specifies the appropriate MMU_* command.
    * -------------
    * ptr[1:0] == MMU_NORMAL_PT_UPDATE:
    * Updates an entry in a page table belonging to PFD. If updating an L1 table,
    * and the new table entry is valid/present, the mapped frame must belong to
    * FD. If attempting to map an I/O page then the caller assumes the privilege
    * of the FD.
    * FD == DOMID_IO: Permit /only/ I/O mappings, at the priv level of the caller.
    * FD == DOMID_XEN: Map restricted areas of Xen's heap space.
    * ptr[:2]  -- Machine address of the page-table entry to modify.
    * val      -- Value to write.
    *
    * There also certain implicit requirements when using this hypercall. The
    * pages that make up a pagetable must be mapped read-only in the guest.
    * This prevents uncontrolled guest updates to the pagetable. Xen strictly
    * enforces this, and will disallow any pagetable update which will end up
    * mapping pagetable page RW, and will disallow using any writable page as a
    * pagetable. In practice it means that when constructing a page table for a
    * process, thread, etc, we MUST be very dilligient in following these rules:
    *  1). Start with top-level page (PGD or in Xen language: L4). Fill out
    *      the entries.
    *  2). Keep on going, filling out the upper (PUD or L3), and middle (PMD
    *      or L2).
    *  3). Start filling out the PTE table (L1) with the PTE entries. Once
    *      done, make sure to set each of those entries to RO (so writeable bit
    *      is unset). Once that has been completed, set the PMD (L2) for this
    *      PTE table as RO.
    *  4). When completed with all of the PMD (L2) entries, and all of them have
    *      been set to RO, make sure to set RO the PUD (L3). Do the same
    *      operation on PGD (L4) pagetable entries that have a PUD (L3) entry.
    *  5). Now before you can use those pages (so setting the cr3), you MUST also
    *      pin them so that the hypervisor can verify the entries. This is done
    *      via the HYPERVISOR_mmuext_op(MMUEXT_PIN_L4_TABLE, guest physical frame
    *      number of the PGD (L4)). And this point the HYPERVISOR_mmuext_op(
    *      MMUEXT_NEW_BASEPTR, guest physical frame number of the PGD (L4)) can be
    *      issued.
    * For 32-bit guests, the L4 is not used (as there is less pagetables), so
    * instead use L3.
    * At this point the pagetables can be modified using the MMU_NORMAL_PT_UPDATE
    * hypercall. Also if so desired the OS can also try to write to the PTE
    * and be trapped by the hypervisor (as the PTE entry is RO).
    *
    * To deallocate the pages, the operations are the reverse of the steps
    * mentioned above. The argument is MMUEXT_UNPIN_TABLE for all levels and the
    * pagetable MUST not be in use (meaning that the cr3 is not set to it).
    *
    * ptr[1:0] == MMU_MACHPHYS_UPDATE:
    * Updates an entry in the machine->pseudo-physical mapping table.
    * ptr[:2]  -- Machine address within the frame whose mapping to modify.
    *             The frame must belong to the FD, if one is specified.
    * val      -- Value to write into the mapping entry.
    *
    * ptr[1:0] == MMU_PT_UPDATE_PRESERVE_AD:
    * As MMU_NORMAL_PT_UPDATE above, but A/D bits currently in the PTE are ORed
    * with those in @val.
    *
    * ptr[1:0] == MMU_PT_UPDATE_NO_TRANSLATE:
    * As MMU_NORMAL_PT_UPDATE above, but @val is not translated though FD
    * page tables.
    *
    * @val is usually the machine frame number along with some attributes.
    * The attributes by default follow the architecture defined bits. Meaning that
    * if this is a X86_64 machine and four page table layout is used, the layout
    * of val is:
    *  - 63 if set means No execute (NX)
    *  - 46-13 the machine frame number
    *  - 12 available for guest
    *  - 11 available for guest
    *  - 10 available for guest
    *  - 9 available for guest
    *  - 8 global
    *  - 7 PAT (PSE is disabled, must use hypercall to make 4MB or 2MB pages)
    *  - 6 dirty
    *  - 5 accessed
    *  - 4 page cached disabled
    *  - 3 page write through
    *  - 2 userspace accessible
    *  - 1 writeable
    *  - 0 present
    *
    *  The one bits that does not fit with the default layout is the PAGE_PSE
    *  also called PAGE_PAT). The MMUEXT_[UN]MARK_SUPER arguments to the
    *  HYPERVISOR_mmuext_op serve as mechanism to set a pagetable to be 4MB
    *  (or 2MB) instead of using the PAGE_PSE bit.
    *
    *  The reason that the PAGE_PSE (bit 7) is not being utilized is due to Xen
    *  using it as the Page Attribute Table (PAT) bit - for details on it please
    *  refer to Intel SDM 10.12. The PAT allows to set the caching attributes of
    *  pages instead of using MTRRs.
    *
    *  The PAT MSR is as follows (it is a 64-bit value, each entry is 8 bits):
    *                    PAT4                 PAT0
    *  +-----+-----+----+----+----+-----+----+----+
    *  | UC  | UC- | WC | WB | UC | UC- | WC | WB |  <= Linux
    *  +-----+-----+----+----+----+-----+----+----+
    *  | UC  | UC- | WT | WB | UC | UC- | WT | WB |  <= BIOS (default when machine boots)
    *  +-----+-----+----+----+----+-----+----+----+
    *  | rsv | rsv | WP | WC | UC | UC- | WT | WB |  <= Xen
    *  +-----+-----+----+----+----+-----+----+----+
    *
    *  The lookup of this index table translates to looking up
    *  Bit 7, Bit 4, and Bit 3 of val entry:
    *
    *  PAT/PSE (bit 7) ... PCD (bit 4) .. PWT (bit 3).
    *
    *  If all bits are off, then we are using PAT0. If bit 3 turned on,
    *  then we are using PAT1, if bit 3 and bit 4, then PAT2..
    *
    *  As you can see, the Linux PAT1 translates to PAT4 under Xen. Which means
    *  that if a guest that follows Linux's PAT setup and would like to set Write
    *  Combined on pages it MUST use PAT4 entry. Meaning that Bit 7 (PAGE_PAT) is
    *  set. For example, under Linux it only uses PAT0, PAT1, and PAT2 for the
    *  caching as:
    *
    *   WB = none (so PAT0)
    *   WC = PWT (bit 3 on)
    *   UC = PWT | PCD (bit 3 and 4 are on).
    *
    * To make it work with Xen, it needs to translate the WC bit as so:
    *
    *  PWT (so bit 3 on) --> PAT (so bit 7 is on) and clear bit 3
    *
    * And to translate back it would:
    *
    * PAT (bit 7 on) --> PWT (bit 3 on) and clear bit 7.
    */
   #define MMU_NORMAL_PT_UPDATE       0 /* checked '*ptr = val'. ptr is MA.      */
   #define MMU_MACHPHYS_UPDATE        1 /* ptr = MA of frame to modify entry for */
   #define MMU_PT_UPDATE_PRESERVE_AD  2 /* atomically: *ptr = val | (*ptr&(A|D)) */
   #define MMU_PT_UPDATE_NO_TRANSLATE 3 /* checked '*ptr = val'. ptr is MA.      */
                                        /* val never translated.                 */
   
   /*
    * MMU EXTENDED OPERATIONS
    *
    * ` enum neg_errnoval
    * ` HYPERVISOR_mmuext_op(mmuext_op_t uops[],
    * `                      unsigned int count,
    * `                      unsigned int *pdone,
    * `                      unsigned int foreigndom)
    */
   /* HYPERVISOR_mmuext_op() accepts a list of mmuext_op structures.
    * A foreigndom (FD) can be specified (or DOMID_SELF for none).
    * Where the FD has some effect, it is described below.
    *
    * cmd: MMUEXT_(UN)PIN_*_TABLE
    * mfn: Machine frame number to be (un)pinned as a p.t. page.
    *      The frame must belong to the FD, if one is specified.
    *
    * cmd: MMUEXT_NEW_BASEPTR
    * mfn: Machine frame number of new page-table base to install in MMU.
    *
    * cmd: MMUEXT_NEW_USER_BASEPTR [x86/64 only]
    * mfn: Machine frame number of new page-table base to install in MMU
    *      when in user space.
    *
    * cmd: MMUEXT_TLB_FLUSH_LOCAL
    * No additional arguments. Flushes local TLB.
    *
    * cmd: MMUEXT_INVLPG_LOCAL
    * linear_addr: Linear address to be flushed from the local TLB.
    *
    * cmd: MMUEXT_TLB_FLUSH_MULTI
    * vcpumask: Pointer to bitmap of VCPUs to be flushed.
    *
    * cmd: MMUEXT_INVLPG_MULTI
    * linear_addr: Linear address to be flushed.
    * vcpumask: Pointer to bitmap of VCPUs to be flushed.
    *
    * cmd: MMUEXT_TLB_FLUSH_ALL
    * No additional arguments. Flushes all VCPUs' TLBs.
    *
    * cmd: MMUEXT_INVLPG_ALL
    * linear_addr: Linear address to be flushed from all VCPUs' TLBs.
    *
    * cmd: MMUEXT_FLUSH_CACHE
    * No additional arguments. Writes back and flushes cache contents.
    *
    * cmd: MMUEXT_FLUSH_CACHE_GLOBAL
    * No additional arguments. Writes back and flushes cache contents
    * on all CPUs in the system.
    *
    * cmd: MMUEXT_SET_LDT
    * linear_addr: Linear address of LDT base (NB. must be page-aligned).
    * nr_ents: Number of entries in LDT.
    *
    * cmd: MMUEXT_CLEAR_PAGE
    * mfn: Machine frame number to be cleared.
    *
    * cmd: MMUEXT_COPY_PAGE
    * mfn: Machine frame number of the destination page.
    * src_mfn: Machine frame number of the source page.
    *
    * cmd: MMUEXT_[UN]MARK_SUPER
    * mfn: Machine frame number of head of superpage to be [un]marked.
    */
   /* ` enum mmuext_cmd { */
   #define MMUEXT_PIN_L1_TABLE      0
   #define MMUEXT_PIN_L2_TABLE      1
   #define MMUEXT_PIN_L3_TABLE      2
   #define MMUEXT_PIN_L4_TABLE      3
   #define MMUEXT_UNPIN_TABLE       4
   #define MMUEXT_NEW_BASEPTR       5
   #define MMUEXT_TLB_FLUSH_LOCAL   6
   #define MMUEXT_INVLPG_LOCAL      7
   #define MMUEXT_TLB_FLUSH_MULTI   8
   #define MMUEXT_INVLPG_MULTI      9
   #define MMUEXT_TLB_FLUSH_ALL    10
   #define MMUEXT_INVLPG_ALL       11
   #define MMUEXT_FLUSH_CACHE      12
   #define MMUEXT_SET_LDT          13
   #define MMUEXT_NEW_USER_BASEPTR 15
   #define MMUEXT_CLEAR_PAGE       16
   #define MMUEXT_COPY_PAGE        17
   #define MMUEXT_FLUSH_CACHE_GLOBAL 18
   #define MMUEXT_MARK_SUPER       19
   #define MMUEXT_UNMARK_SUPER     20
   /* ` } */
   
   #ifndef __ASSEMBLY__
   struct mmuext_op {
       unsigned int cmd; /* => enum mmuext_cmd */
       union {
           /* [UN]PIN_TABLE, NEW_BASEPTR, NEW_USER_BASEPTR
            * CLEAR_PAGE, COPY_PAGE, [UN]MARK_SUPER */
           xen_pfn_t     mfn;
           /* INVLPG_LOCAL, INVLPG_ALL, SET_LDT */
           unsigned long linear_addr;
       } arg1;
       union {
           /* SET_LDT */
           unsigned int nr_ents;
           /* TLB_FLUSH_MULTI, INVLPG_MULTI */
   #if __XEN_INTERFACE_VERSION__ >= 0x00030205
           XEN_GUEST_HANDLE(const_void) vcpumask;
   #else
           const void *vcpumask;
   #endif
           /* COPY_PAGE */
           xen_pfn_t src_mfn;
       } arg2;
   };
   typedef struct mmuext_op mmuext_op_t;
   DEFINE_XEN_GUEST_HANDLE(mmuext_op_t);
   #endif
   
   /*
    * ` enum neg_errnoval
    * ` HYPERVISOR_update_va_mapping(unsigned long va, u64 val,
    * `                              enum uvm_flags flags)
    * `
    * ` enum neg_errnoval
    * ` HYPERVISOR_update_va_mapping_otherdomain(unsigned long va, u64 val,
    * `                                          enum uvm_flags flags,
    * `                                          domid_t domid)
    * `
    * ` @va: The virtual address whose mapping we want to change
    * ` @val: The new page table entry, must contain a machine address
    * ` @flags: Control TLB flushes
    */
   /* These are passed as 'flags' to update_va_mapping. They can be ORed. */
   /* When specifying UVMF_MULTI, also OR in a pointer to a CPU bitmap.   */
   /* UVMF_LOCAL is merely UVMF_MULTI with a NULL bitmap pointer.         */
   /* ` enum uvm_flags { */
   #define UVMF_NONE           (xen_mk_ulong(0)<<0) /* No flushing at all.   */
   #define UVMF_TLB_FLUSH      (xen_mk_ulong(1)<<0) /* Flush entire TLB(s).  */
   #define UVMF_INVLPG         (xen_mk_ulong(2)<<0) /* Flush only one entry. */
   #define UVMF_FLUSHTYPE_MASK (xen_mk_ulong(3)<<0)
   #define UVMF_MULTI          (xen_mk_ulong(0)<<2) /* Flush subset of TLBs. */
   #define UVMF_LOCAL          (xen_mk_ulong(0)<<2) /* Flush local TLB.      */
   #define UVMF_ALL            (xen_mk_ulong(1)<<2) /* Flush all TLBs.       */
   /* ` } */
   
   /*
    * ` int
    * ` HYPERVISOR_console_io(unsigned int cmd,
    * `                       unsigned int count,
    * `                       char buffer[]);
    *
    * @cmd: Command (see below)
    * @count: Size of the buffer to read/write
    * @buffer: Pointer in the guest memory
    *
    * List of commands:
    *
    *  * CONSOLEIO_write: Write the buffer to Xen console.
    *      For the hardware domain, all the characters in the buffer will
    *      be written. Characters will be printed directly to the console.
    *      For all the other domains, only the printable characters will be
    *      written. Characters may be buffered until a newline (i.e '\n') is
    *      found.
    *      @return 0 on success, otherwise return an error code.
    *  * CONSOLEIO_read: Attempts to read up to @count characters from Xen
    *      console. The maximum buffer size (i.e. @count) supported is 2GB.
    *      @return the number of characters read on success, otherwise return
    *      an error code.
    */
   #define CONSOLEIO_write         0
   #define CONSOLEIO_read          1
   
   /*
    * Commands to HYPERVISOR_vm_assist().
    */
   #define VMASST_CMD_enable                0
   #define VMASST_CMD_disable               1
   
   /* x86/32 guests: simulate full 4GB segment limits. */
   #define VMASST_TYPE_4gb_segments         0
   
   /* x86/32 guests: trap (vector 15) whenever above vmassist is used. */
   #define VMASST_TYPE_4gb_segments_notify  1
   
   /*
    * x86 guests: support writes to bottom-level PTEs.
    * NB1. Page-directory entries cannot be written.
    * NB2. Guest must continue to remove all writable mappings of PTEs.
    */
   #define VMASST_TYPE_writable_pagetables  2
   
   /* x86/PAE guests: support PDPTs above 4GB. */
   #define VMASST_TYPE_pae_extended_cr3     3
   
   /*
    * x86 guests: Sane behaviour for virtual iopl
    *  - virtual iopl updated from do_iret() hypercalls.
    *  - virtual iopl reported in bounce frames.
    *  - guest kernels assumed to be level 0 for the purpose of iopl checks.
    */
   #define VMASST_TYPE_architectural_iopl   4
   
   /*
    * All guests: activate update indicator in vcpu_runstate_info
    * Enable setting the XEN_RUNSTATE_UPDATE flag in guest memory mapped
    * vcpu_runstate_info during updates of the runstate information.
    */
   #define VMASST_TYPE_runstate_update_flag 5
   
   /*
    * x86/64 guests: strictly hide M2P from user mode.
    * This allows the guest to control respective hypervisor behavior:
    * - when not set, L4 tables get created with the respective slot blank,
    *   and whenever the L4 table gets used as a kernel one the missing
    *   mapping gets inserted,
    * - when set, L4 tables get created with the respective slot initialized
    *   as before, and whenever the L4 table gets used as a user one the
    *   mapping gets zapped.
    */
   #define VMASST_TYPE_m2p_strict           32
   
   #if __XEN_INTERFACE_VERSION__ < 0x00040600
   #define MAX_VMASST_TYPE                  3
   #endif
   
   /* Domain ids >= DOMID_FIRST_RESERVED cannot be used for ordinary domains. */
   #define DOMID_FIRST_RESERVED xen_mk_uint(0x7FF0)
   
   /* DOMID_SELF is used in certain contexts to refer to oneself. */
   #define DOMID_SELF           xen_mk_uint(0x7FF0)
   
   /*
    * 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 as HYPERVISOR_mmu_update()'s and
    * HYPERVISOR_update_va_mapping_otherdomain()'s "foreigndom" argument. For
    * HYPERVISOR_mmu_update() context it can be specified by any calling domain,
    * otherwise it's only permitted if the caller is privileged.
    */
   #define DOMID_IO             xen_mk_uint(0x7FF1)
   
   /*
    * 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 as
    * - HYPERVISOR_mmu_update()'s, HYPERVISOR_mmuext_op()'s, or
    *   HYPERVISOR_update_va_mapping_otherdomain()'s "foreigndom" argument,
    * - with XENMAPSPACE_gmfn_foreign,
    * and is only permitted if the caller is privileged.
    */
   #define DOMID_XEN            xen_mk_uint(0x7FF2)
   
   /*
    * DOMID_COW is used as the owner of sharable pages */
   #define DOMID_COW            xen_mk_uint(0x7FF3)
   
   /* DOMID_INVALID is used to identify pages with unknown owner. */
   #define DOMID_INVALID        xen_mk_uint(0x7FF4)
   
   /* Idle domain. */
   #define DOMID_IDLE           xen_mk_uint(0x7FFF)
   
   /* Mask for valid domain id values */
   #define DOMID_MASK           xen_mk_uint(0x7FFF)
   
   #ifndef __ASSEMBLY__
   
   typedef uint16_t domid_t;
   
   /*
    * Send an array of these to HYPERVISOR_mmu_update().
    * NB. The fields are natural pointer/address size for this architecture.
    */
   struct mmu_update {
       uint64_t ptr;       /* Machine address of PTE. */
       uint64_t val;       /* New contents of PTE.    */
   };
   typedef struct mmu_update mmu_update_t;
   DEFINE_XEN_GUEST_HANDLE(mmu_update_t);
   
   /*
    * ` enum neg_errnoval
    * ` HYPERVISOR_multicall(multicall_entry_t call_list[],
    * `                      uint32_t nr_calls);
    *
    * NB. The fields are logically the natural register size for this
    * architecture. In cases where xen_ulong_t is larger than this then
    * any unused bits in the upper portion must be zero.
    */
   struct multicall_entry {
       xen_ulong_t op, result;
       xen_ulong_t args[6];
   };
   typedef struct multicall_entry multicall_entry_t;
   DEFINE_XEN_GUEST_HANDLE(multicall_entry_t);
   
   #if __XEN_INTERFACE_VERSION__ < 0x00040400
   /*
    * Event channel endpoints per domain (when using the 2-level ABI):
    *  1024 if a long is 32 bits; 4096 if a long is 64 bits.
    */
   #define NR_EVENT_CHANNELS EVTCHN_2L_NR_CHANNELS
   #endif
   
   struct vcpu_time_info {
       /*
        * Updates to the following values are preceded and followed by an
        * increment of 'version'. The guest can therefore detect updates by
        * looking for changes to 'version'. If the least-significant bit of
        * the version number is set then an update is in progress and the guest
        * must wait to read a consistent set of values.
        * The correct way to interact with the version number is similar to
        * Linux's seqlock: see the implementations of read_seqbegin/read_seqretry.
        */
       uint32_t version;
       uint32_t pad0;
       uint64_t tsc_timestamp;   /* TSC at last update of time vals.  */
       uint64_t system_time;     /* Time, in nanosecs, since boot.    */
       /*
        * Current system time:
        *   system_time +
        *   ((((tsc - tsc_timestamp) << tsc_shift) * tsc_to_system_mul) >> 32)
        * CPU frequency (Hz):
        *   ((10^9 << 32) / tsc_to_system_mul) >> tsc_shift
        */
       uint32_t tsc_to_system_mul;
       int8_t   tsc_shift;
   #if __XEN_INTERFACE_VERSION__ > 0x040600
       uint8_t  flags;
       uint8_t  pad1[2];
   #else
       int8_t   pad1[3];
   #endif
   }; /* 32 bytes */
   typedef struct vcpu_time_info vcpu_time_info_t;
   
   #define XEN_PVCLOCK_TSC_STABLE_BIT     (1 << 0)
   #define XEN_PVCLOCK_GUEST_STOPPED      (1 << 1)
   
   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.
        */
       uint8_t evtchn_upcall_pending;
   #ifdef XEN_HAVE_PV_UPCALL_MASK
       uint8_t evtchn_upcall_mask;
   #else /* XEN_HAVE_PV_UPCALL_MASK */
       uint8_t pad0;
   #endif /* XEN_HAVE_PV_UPCALL_MASK */
       xen_ulong_t evtchn_pending_sel;
       struct arch_vcpu_info arch;
       struct vcpu_time_info time;
   }; /* 64 bytes (x86) */
   #ifndef __XEN__
   typedef struct vcpu_info vcpu_info_t;
   #endif
   
   /*
    * `incontents 200 startofday_shared Start-of-day shared data structure
    * Xen/kernel shared data -- pointer provided in start_info.
    *
    * This structure is defined to be both smaller than a page, and the
    * only data on the shared page, but may vary in actual size even within
    * compatible Xen versions; guests should not rely on the size
    * of this structure remaining constant.
    */
   struct shared_info {
       struct vcpu_info vcpu_info[XEN_LEGACY_MAX_VCPUS];
   
       /*
        * 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 by control software or RTC emulation.
        * Guests should base their gettimeofday() syscall on this
        * wallclock-base value.
        * The values of wc_sec and wc_nsec are offsets from the Unix epoch
        * adjusted by the domain's 'time offset' (in seconds) as set either
        * by XEN_DOMCTL_settimeoffset, or adjusted via a guest write to the
        * emulated RTC.
        */
       uint32_t wc_version;      /* Version counter: see vcpu_time_info_t. */
       uint32_t wc_sec;
       uint32_t wc_nsec;
   #if !defined(__i386__)
       uint32_t wc_sec_hi;
   # define xen_wc_sec_hi wc_sec_hi
   #elif !defined(__XEN__) && !defined(__XEN_TOOLS__)
   # define xen_wc_sec_hi arch.wc_sec_hi
   #endif
   
       struct arch_shared_info arch;
   
   };
   #ifndef __XEN__
   typedef struct shared_info shared_info_t;
   #endif
   
   /*
    * `incontents 200 startofday Start-of-day memory layout
    *
    *  1. The domain is started within contiguous virtual-memory region.
    *  2. The contiguous region ends on an aligned 4MB boundary.
    *  3. This the order of bootstrap elements in the initial virtual region:
    *      a. relocated kernel image
    *      b. initial ram disk              [mod_start, mod_len]
    *         (may be omitted)
    *      c. list of allocated page frames [mfn_list, nr_pages]
    *         (unless relocated due to XEN_ELFNOTE_INIT_P2M)
    *      d. start_info_t structure        [register rSI (x86)]
    *         in case of dom0 this page contains the console info, too
    *      e. unless dom0: xenstore ring page
    *      f. unless dom0: console ring page
    *      g. bootstrap page tables         [pt_base and CR3 (x86)]
    *      h. bootstrap stack               [register ESP (x86)]
    *  4. Bootstrap elements are packed together, but each is 4kB-aligned.
    *  5. The list of page frames forms a contiguous 'pseudo-physical' memory
    *     layout for the domain. In particular, the bootstrap virtual-memory
    *     region is a 1:1 mapping to the first section of the pseudo-physical map.
    *  6. All bootstrap elements are mapped read-writable for the guest OS. The
    *     only exception is the bootstrap page table, which is mapped read-only.
    *  7. There is guaranteed to be at least 512kB padding after the final
    *     bootstrap element. If necessary, the bootstrap virtual region is
    *     extended by an extra 4MB to ensure this.
    *
    * Note: Prior to 25833:bb85bbccb1c9. ("x86/32-on-64 adjust Dom0 initial page
    * table layout") a bug caused the pt_base (3.g above) and cr3 to not point
    * to the start of the guest page tables (it was offset by two pages).
    * This only manifested itself on 32-on-64 dom0 kernels and not 32-on-64 domU
    * or 64-bit kernels of any colour. The page tables for a 32-on-64 dom0 got
    * allocated in the order: 'first L1','first L2', 'first L3', so the offset
    * to the page table base is by two pages back. The initial domain if it is
    * 32-bit and runs under a 64-bit hypervisor should _NOT_ use two of the
    * pages preceding pt_base and mark them as reserved/unused.
    */
   #ifdef XEN_HAVE_PV_GUEST_ENTRY
   struct start_info {
       /* THE FOLLOWING ARE FILLED IN BOTH ON INITIAL BOOT AND ON RESUME.    */
       char magic[32];             /* "xen-<version>-<platform>".            */
       unsigned long nr_pages;     /* Total pages allocated to this domain.  */
       unsigned long shared_info;  /* MACHINE address of shared info struct. */
       uint32_t flags;             /* SIF_xxx flags.                         */
       xen_pfn_t store_mfn;        /* MACHINE page number of shared page.    */
       uint32_t store_evtchn;      /* Event channel for store communication. */
       union {
           struct {
               xen_pfn_t mfn;      /* MACHINE page number of console page.   */
               uint32_t  evtchn;   /* Event channel for console page.        */
           } domU;
           struct {
               uint32_t info_off;  /* Offset of console_info struct.         */
               uint32_t info_size; /* Size of console_info struct from start.*/
           } dom0;
       } console;
       /* THE FOLLOWING ARE ONLY FILLED IN ON INITIAL BOOT (NOT RESUME).     */
       unsigned long pt_base;      /* VIRTUAL address of page directory.     */
       unsigned long nr_pt_frames; /* Number of bootstrap p.t. frames.       */
       unsigned long mfn_list;     /* VIRTUAL address of page-frame list.    */
       unsigned long mod_start;    /* VIRTUAL address of pre-loaded module   */
                                   /* (PFN of pre-loaded module if           */
                                   /*  SIF_MOD_START_PFN set in flags).      */
       unsigned long mod_len;      /* Size (bytes) of pre-loaded module.     */
   #define MAX_GUEST_CMDLINE 1024
       int8_t cmd_line[MAX_GUEST_CMDLINE];
       /* The pfn range here covers both page table and p->m table frames.   */
       unsigned long first_p2m_pfn;/* 1st pfn forming initial P->M table.    */
       unsigned long nr_p2m_frames;/* # of pfns forming initial P->M table.  */
   };
   typedef struct start_info start_info_t;
   
   /* New console union for dom0 introduced in 0x00030203. */
   #if __XEN_INTERFACE_VERSION__ < 0x00030203
   #define console_mfn    console.domU.mfn
   #define console_evtchn console.domU.evtchn
   #endif
   #endif /* XEN_HAVE_PV_GUEST_ENTRY */
   
   /* These flags are passed in the 'flags' field of start_info_t. */
   #define SIF_PRIVILEGED    (1<<0)  /* Is the domain privileged? */
   #define SIF_INITDOMAIN    (1<<1)  /* Is this the initial control domain? */
   #define SIF_MULTIBOOT_MOD (1<<2)  /* Is mod_start a multiboot module? */
   #define SIF_MOD_START_PFN (1<<3)  /* Is mod_start a PFN? */
   #define SIF_VIRT_P2M_4TOOLS (1<<4) /* Do Xen tools understand a virt. mapped */
                                      /* P->M making the 3 level tree obsolete? */
   #define SIF_PM_MASK       (0xFF<<8) /* reserve 1 byte for xen-pm options */
   
   /*
    * A multiboot module is a package containing modules very similar to a
    * multiboot module array. The only differences are:
    * - the array of module descriptors is by convention simply at the beginning
    *   of the multiboot module,
    * - addresses in the module descriptors are based on the beginning of the
    *   multiboot module,
    * - the number of modules is determined by a termination descriptor that has
    *   mod_start == 0.
    *
    * This permits to both build it statically and reference it in a configuration
    * file, and let the PV guest easily rebase the addresses to virtual addresses
    * and at the same time count the number of modules.
    */
   struct xen_multiboot_mod_list
   {
       /* Address of first byte of the module */
       uint32_t mod_start;
       /* Address of last byte of the module (inclusive) */
       uint32_t mod_end;
       /* Address of zero-terminated command line */
       uint32_t cmdline;
       /* Unused, must be zero */
       uint32_t pad;
   };
   /*
    * `incontents 200 startofday_dom0_console Dom0_console
    *
    * The console structure in start_info.console.dom0
    *
    * This structure includes a variety of information required to
    * have a working VGA/VESA console.
    */
   typedef struct dom0_vga_console_info {
       uint8_t video_type; /* DOM0_VGA_CONSOLE_??? */
   #define XEN_VGATYPE_TEXT_MODE_3 0x03
   #define XEN_VGATYPE_VESA_LFB    0x23
   #define XEN_VGATYPE_EFI_LFB     0x70
   
       union {
           struct {
               /* Font height, in pixels. */
               uint16_t font_height;
               /* Cursor location (column, row). */
               uint16_t cursor_x, cursor_y;
               /* Number of rows and columns (dimensions in characters). */
               uint16_t rows, columns;
           } text_mode_3;
   
           struct {
               /* Width and height, in pixels. */
               uint16_t width, height;
               /* Bytes per scan line. */
               uint16_t bytes_per_line;
               /* Bits per pixel. */
               uint16_t bits_per_pixel;
               /* LFB physical address, and size (in units of 64kB). */
               uint32_t lfb_base;
               uint32_t lfb_size;
               /* RGB mask offsets and sizes, as defined by VBE 1.2+ */
               uint8_t  red_pos, red_size;
               uint8_t  green_pos, green_size;
               uint8_t  blue_pos, blue_size;
               uint8_t  rsvd_pos, rsvd_size;
   #if __XEN_INTERFACE_VERSION__ >= 0x00030206
               /* VESA capabilities (offset 0xa, VESA command 0x4f00). */
               uint32_t gbl_caps;
               /* Mode attributes (offset 0x0, VESA command 0x4f01). */
               uint16_t mode_attrs;
               uint16_t pad;
   #endif
   #if __XEN_INTERFACE_VERSION__ >= 0x00040d00
               /* high 32 bits of lfb_base */
               uint32_t ext_lfb_base;
   #endif
           } vesa_lfb;
       } u;
   } dom0_vga_console_info_t;
   #define xen_vga_console_info dom0_vga_console_info
   #define xen_vga_console_info_t dom0_vga_console_info_t
   
   typedef uint8_t xen_domain_handle_t[16];
   
   __DEFINE_XEN_GUEST_HANDLE(uint8,  uint8_t);
   __DEFINE_XEN_GUEST_HANDLE(uint16, uint16_t);
   __DEFINE_XEN_GUEST_HANDLE(uint32, uint32_t);
   __DEFINE_XEN_GUEST_HANDLE(uint64, uint64_t);
   
   typedef struct {
       uint8_t a[16];
   } xen_uuid_t;
   
   /*
    * XEN_DEFINE_UUID(0x00112233, 0x4455, 0x6677, 0x8899,
    *                 0xaa, 0xbb, 0xcc, 0xdd, 0xee, 0xff)
    * will construct UUID 00112233-4455-6677-8899-aabbccddeeff presented as
    * {0x00, 0x11, 0x22, 0x33, 0x44, 0x55, 0x66, 0x77, 0x88,
    * 0x99, 0xaa, 0xbb, 0xcc, 0xdd, 0xee, 0xff};
    *
    * NB: This is compatible with Linux kernel and with libuuid, but it is not
    * compatible with Microsoft, as they use mixed-endian encoding (some
    * components are little-endian, some are big-endian).
    */
   #define XEN_DEFINE_UUID_(a, b, c, d, e1, e2, e3, e4, e5, e6)            \
       {{((a) >> 24) & 0xFF, ((a) >> 16) & 0xFF,                           \
        ((a) >>  8) & 0xFF, ((a) >>  0) & 0xFF,                           \
        ((b) >>  8) & 0xFF, ((b) >>  0) & 0xFF,                           \
        ((c) >>  8) & 0xFF, ((c) >>  0) & 0xFF,                           \
        ((d) >>  8) & 0xFF, ((d) >>  0) & 0xFF,                           \
                  e1, e2, e3, e4, e5, e6}}
  
  #if defined(__STDC_VERSION__) ? __STDC_VERSION__ >= 199901L : defined(__GNUC__)
  #define XEN_DEFINE_UUID(a, b, c, d, e1, e2, e3, e4, e5, e6)             \
      ((xen_uuid_t)XEN_DEFINE_UUID_(a, b, c, d, e1, e2, e3, e4, e5, e6))
  #else
  #define XEN_DEFINE_UUID(a, b, c, d, e1, e2, e3, e4, e5, e6)             \
      XEN_DEFINE_UUID_(a, b, c, d, e1, e2, e3, e4, e5, e6)
  #endif /* __STDC_VERSION__ / __GNUC__ */
  
  #endif /* !__ASSEMBLY__ */
  
  /* Default definitions for macros used by domctl/sysctl. */
  #if defined(__XEN__) || defined(__XEN_TOOLS__)
  
  #ifndef int64_aligned_t
  #define int64_aligned_t int64_t
  #endif
  #ifndef uint64_aligned_t
  #define uint64_aligned_t uint64_t
  #endif
  #ifndef XEN_GUEST_HANDLE_64
  #define XEN_GUEST_HANDLE_64(name) XEN_GUEST_HANDLE(name)
  #endif
  
  #ifndef __ASSEMBLY__
  struct xenctl_bitmap {
      XEN_GUEST_HANDLE_64(uint8) bitmap;
      uint32_t nr_bits;
  };
  #endif
  
  #endif /* defined(__XEN__) || defined(__XEN_TOOLS__) */
  
  #endif /* __XEN_PUBLIC_XEN_H__ */
  
  /*
   * Local variables:
   * mode: C
   * c-file-style: "BSD"
   * c-basic-offset: 4
   * tab-width: 4
   * indent-tabs-mode: nil
   * End:
   */

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