monitor.h

Bochs is a highly portable open source IA-32 (x86) PC emulator written in C++, that runs on most po

/*
 *  plex86: run multiple x86 operating systems concurrently
 *  Copyright (C) 1999-2003 Kevin P. Lawton
 *
 *  monitor.h: main VM monitor defines
 *
 *  This library is free software; you can redistribute it and/or
 *  modify it under the terms of the GNU Lesser General Public
 *  License as published by the Free Software Foundation; either
 *  version 2 of the License, or (at your option) any later version.
 *
 *  This library is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 *  Lesser General Public License for more details.
 *
 *  You should have received a copy of the GNU Lesser General Public
 *  License along with this library; if not, write to the Free Software
 *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307 USA
 */

#ifndef __MONITOR_H__
#define __MONITOR_H__

#if defined(__NetBSD__) || defined(__FreeBSD__)
#include <machine/stdarg.h>
#else
#include <stdarg.h>
#endif


#include "descriptor.h"
#include "descriptor2.h"
#include "tss.h"
#include "paging.h"
#include "eflags.h"
#include "guest_context.h"

#ifndef UNUSED
#  define UNUSED(x) ((void)(x))
#endif


/* Method1: push event info (CPU pushes error code before) */
typedef struct 
{
  Bit8u  pushl;    /* Always 0x68 == pushl            */
  Bit32u vector;   /* Interrupt vector number         */
  Bit8u  jmp;      /* Always 0xe9 == jmp              */
  Bit32u reloc;    /* Relative offset of destination  */
} __attribute__ ((packed)) idt_method1_t;

/* Method2: push a dummy error first, then event info */
typedef struct 
{
  Bit8u  pushla;   /* Always 0x68 == pushl            */
  Bit32u dummy;    /* Dummy error code                */
  Bit8u  pushlb;   /* Always 0x68 == pushl            */
  Bit32u vector;   /* Interrupt vector number         */
  Bit8u  jmp;      /* Always 0xe9 == jmp              */
  Bit32u reloc;    /* Relative offset of destination  */
} __attribute__ ((packed)) idt_method2_t;

typedef union 
{
  idt_method1_t m1;
  idt_method2_t m2;
} idt_stub_t;


/* Nexus fields.  This C structure maps to identical assembly */
/* fields in nexus.S.  Make sure to update both!  These fields */
/* are accessible to the nexus code during the transition from */
/* host<->guest and are stored in a single page. */

typedef struct {
  /* guest pointer to vm_t structure. */
  void          *vm;

  /* These fields are only used by the transition code. */
  /* They hold all info necessary to switch back to the host. */
  gdt_info_t     host_gdt_info;
  gdt_info_t     host_idt_info;
  far_jmp_info_t host_jmp_info;
  far_jmp_info_t host_stack_info;
  Bit16u         host_ldt_sel;
  Bit16u         host_tss_sel;
  Bit32u         host_cr0;
  Bit32u         host_cr2;
  Bit32u         host_cr3;
  Bit32u         host_cr4;

  /* These fields are filled by the host-side code, and used  */
  /* by the transition code.  They contain all info necessary */
  /* to switch to the monitor/guest address space. */
  /* This info changes whenever the monitor migrates. */
  gdt_info_t     mon_gdt_info;
  gdt_info_t     mon_idt_info;
  far_jmp_info_t mon_jmp_info;
  far_jmp_info_t mon_stack_info;
  Bit16u         mon_ldt_sel;
  Bit16u         mon_tss_sel;
  Bit32u         mon_base;
  Bit32u         mon_cr0;
  Bit32u         mon_cr3;
  Bit32u         mon_cr4;
  Bit32u         mon_eflags;

  /* These fields contain info used by the transition code to */
  /* create the temporary identity mapping.  They never change. */
  pageEntry_t    transition_pde;
  pageEntry_t   *transition_pde_p_host;
  pageEntry_t   *transition_pde_p_mon;
  Bit32u         transition_laddr;
} __attribute__ ((packed)) nexus_t;


/* For reference, the following describes where bits from the guest */
/* eflags register are stored/managed. */
/* */
/* Key: */
/*  g: Flag value as requested by guest */
/*  V: Virtualized flag value, as loaded in eflags when guest is executing */
/*  ?: Unhandled yet, request of set bit causes panic for now */
/* */
/*   === ======= ====== ======= ======= ======= */
/*  |I|V|V|A|V|R|0|N|IO|O|D|I|T|S|Z|0|A|0|P|1|C| flag */
/*  |D|I|I|C|M|F| |T|PL|F|F|F|F|F|F| |F| |F| |F| */
/*  | |P|F| | | | | |  | | | | | | | | | | | | | */
/*  |g|?|?|g|V|g|g|g|VV|g|g|V|g|g|g|g|g|g|g|g|g| context->eflags */
/*  | |?|?| |g| | | |gg| | |g| | | | | | | | | | veflags */

/* #define VirtualizedEflags 0x001a3200 */
#define VirtualizedEflags 0x001a3300


/* I define the 'nexus' as the set of data structures which */
/* must exist in the current linear guest address space.  The */
/* host linear address space is not available while the current */
/* guest code is running, since we are using a completely */
/* different set of page mappings for the guest.  However, */
/* at some point an exception/interrupt will occur.  The */
/* interrupt mechanisms require that several structures exist in */
/* the current linear address space in order to service such */
/* an event.  These data structures make up part of our VM, */
/* a thin layer which exists in the guest.  Following is a */
/* list of what data structures compose this 'nexus': */
/* */
/*     - IDT (max  2048 bytes) */
/*     - GDT (max 65536 bytes) */
/*     - LDT (max 65536 bytes) */
/*     - TSS (max  8328 = 104 + 32 int redir + 8192 I/O permissions) */
/*     - kernel stack page */
/*     - transition code (host <--> guest) */
/*     - interrupt handler stubs */
/*     - Page Tables; PDE & PTE pages. */

/*
 * Sizes of various nexus data structures used by the monitor
 */

#define PLEX86_MAX_PHY_MEGS 32
#define PAGESIZE 4096

#define IDT_STUB_SIZE 15
#define BytesToPages(b) ( ((b)+4095) >> 12 )

#define MON_IDT_SIZE       (8*256)
#define MON_GDT_SIZE       (8*512)
#define MON_LDT_SIZE       (8*1)
#define MON_IDT_STUBS_SIZE (IDT_STUB_SIZE*256)
#define MON_TSS_SIZE       (104)

#define MON_IDT_PAGES       BytesToPages(MON_IDT_SIZE)
#define MON_GDT_PAGES       BytesToPages(MON_GDT_SIZE)
#define MON_LDT_PAGES       BytesToPages(MON_LDT_SIZE)
#define MON_IDT_STUBS_PAGES BytesToPages(MON_IDT_STUBS_SIZE)
#define MON_TSS_PAGES       BytesToPages(MON_TSS_SIZE)

#define MAX_MON_GUEST_PAGES    (PLEX86_MAX_PHY_MEGS * 256)
/* +++ MON_PAGE_TABLES is kind of random */
#define MON_PAGE_TABLES    (10*((PLEX86_MAX_PHY_MEGS+3) >> 2))

#define MAX_VM_STRUCT_PAGES (68)

#define LOG_BUFF_PAGES 1
#define LOG_BUFF_SIZE  ((LOG_BUFF_PAGES)*4096)

/*
 *  Pages allocated for the VM by the host kernel driver.
 *  N Megs of physical memory are allocated, per the user's
 *  request, for the guest OS/application code.
 *  Additionally, some other overhead pages are allocated
 *  for structures such as the page directory, page tables,
 *  and other virtualized facilities.
 */

typedef struct {
  /* requested size of the guest[] array in megs and pages */
  unsigned guest_n_megs;
  unsigned guest_n_pages;
  unsigned guest_n_bytes;

  /* pages comprising the vm_t struct itself. */
  Bit32u vm[MAX_VM_STRUCT_PAGES];

  /* for the monitor's page directory */
  Bit32u page_dir;

  /* for the monitor's page table */
  Bit32u page_tbl[MON_PAGE_TABLES];

  /* Map of the linear addresses of page tables currently */
  /* mapped into the monitor space. */
  Bit32u page_tbl_laddr_map;

  /* for the extra page table that maps our nexus code and structures */
  Bit32u nexus_page_tbl;

  /* For the CPU state passed between user and kernel/monitor space. */
  Bit32u guest_cpu;
  void  *guest_cpu_hostOSPtr;

  /* We need a Page Table for identity mapping the transition code */
  /* between host and monitor spaces. */
  Bit32u transition_PT;

  Bit32u log_buffer[LOG_BUFF_PAGES];
  void  *log_buffer_hostOSPtr[LOG_BUFF_PAGES];

  /* Physical addresses of host pages which comprise the actual */
  /* monitor structures.  These will be mapped into the current */
  /* guest task's linear address space as well. */
  Bit32u nexus;
  Bit32u idt[MON_IDT_PAGES];
  Bit32u gdt[MON_GDT_PAGES];
  Bit32u ldt[MON_LDT_PAGES];
  Bit32u tss[MON_TSS_PAGES];
  Bit32u idt_stubs[MON_IDT_STUBS_PAGES];
  } vm_pages_t;


typedef struct {
  pageEntry_t  *page_dir;
  page_t       *page_tbl;
  unsigned     *page_tbl_laddr_map;
  page_t       *nexus_page_tbl;
  guest_cpu_t  *guest_cpu;
  page_t       *transition_PT;
  unsigned char *log_buffer;
  Bit8u        *code_phy_page; /* only use in mon space */
  Bit8u        *tmp_phy_page0; /* only use in mon space */
  Bit8u        *tmp_phy_page1; /* only use in mon space */

  nexus_t      *nexus;
  /* Pointer into the monitor stack, so we can easily retrieve the */
  /* stack snapshot upon interrupt/exception. */
  guest_context_t *guest_context;
  gate_t       *idt;
  descriptor_t *gdt;
  descriptor_t *ldt;
  tss_t        *tss;
  idt_stub_t   *idt_stubs;
  } vm_addr_t;


/* These bits define the possible usage and attributes assigned */
/* to a particular guest physical page.  These are useful for keeping */
/* track of what kinds of system structures are contained in a page */
/* at a given time, and if the page has associated cached code */
/* information in the prescan logic.  We can also tag particular */
/* pages with other more static attributes. */

typedef union {
  struct {
    Bit32u access_perm:2;     /* */
    Bit32u lmap_count:2;      /* */
    Bit32u ptbl:1;            /* page table */
    Bit32u pdir:1;            /* page directory */
    Bit32u spare0:1;          /* (spare) */
    Bit32u memMapIO:1;        /* MemMapIO */
    Bit32u RO:1;              /* RO */
    Bit32u allocated:1;       /* Allocated */
    Bit32u pinned:1;          /* Pinned by host OS. */
    Bit32u spare1:1;          /* (spare) */
    Bit32u laddr_backlink:20; /* 1st unvirtualized laddr backlink */
    } __attribute__ ((packed)) fields;
  Bit32u raw;
  } __attribute__ ((packed)) phy_page_attr_t;

typedef struct {
  phy_page_attr_t attr;
  Bit64u tsc; /* for comparing to CR3 timestamp counter */

  Bit32u hostPPI;
  } __attribute__ ((packed)) phyPageInfo_t;

/* Possible values of the access_perm field above. */
#define PagePermRW      0
#define PagePermRO      1
#define PagePermEmulate 2
#define PagePermNA PagePermEmulate  /* No Access is synomym */


/* Bitmasks to access fields in structure above. */
#define PageUsagePTbl             0x010
#define PageUsagePDir             0x020

#define PageUsageMemMapIO         0x080
#define PageUsageRO               0x100
#define PageUsageAllocated        0x200
#define PageUsageSwappable        0x400

/* Group of attributes which retain their value, even when CR3 */
/* is reloaded and the page mappings are flushed. */
#define PageUsageSticky \
  ( PageUsageMemMapIO | PageUsageRO | \
    PageUsageAllocated | PageUsageSwappable )

/* Group of attributes which are not compatible with a Page Table */
/* occupying a physical page. */
#define PageBadUsage4PTbl \
  ( PageUsagePDir | PageUsageMemMapIO | PageUsageRO )

/* Group of attributes which are not compatible with a Page Directory */
/* occupying a physical page.  Keep in mind, when the PDir is marked, */
/* no other dynamic bits will be set. */
#define PageBadUsage4PDir \
  ( PageUsageMemMapIO | PageUsageRO )

#define PageUsageCausesNA \
  ( PageUsagePTbl | PageUsagePDir | PageUsageMemMapIO )
#define PageUsageCausesRO \
  ( PageUsageRO )

#define PDEUnhandled 0x000001d8
#define PTEUnhandled 0x00000198


#define ExceptionDE   0 /* Divide Error (fault) */
#define ExceptionDB   1 /* Debug (fault/trap) */
#define ExceptionBP   3 /* Breakpoint (trap) */
#define ExceptionOF   4 /* Overflow (trap) */
#define ExceptionBR   5 /* BOUND (fault) */
#define ExceptionUD   6
#define ExceptionNM   7
#define ExceptionDF   8
#define ExceptionTS  10
#define ExceptionNP  11
#define ExceptionSS  12
#define ExceptionGP  13
#define ExceptionPF  14
#define ExceptionMF  16
#define ExceptionAC  17