arch/s390/kvm/gaccess.h

   1 /*
   2  * access guest memory
   3  *
   4  * Copyright IBM Corp. 2008, 2014
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License (version 2 only)
   8  * as published by the Free Software Foundation.
   9  *
  10  *    Author(s): Carsten Otte <cotte@de.ibm.com>
  11  */
  12
  13 #ifndef __KVM_S390_GACCESS_H
  14 #define __KVM_S390_GACCESS_H
  15
  16 #include <linux/compiler.h>
  17 #include <linux/kvm_host.h>
  18 #include <linux/uaccess.h>
  19 #include <linux/ptrace.h>
  20 #include "kvm-s390.h"
  21
  22 /**
  23  * kvm_s390_real_to_abs - convert guest real address to guest absolute address
  24  * @vcpu - guest virtual cpu
  25  * @gra - guest real address
  26  *
  27  * Returns the guest absolute address that corresponds to the passed guest real
  28  * address @gra of a virtual guest cpu by applying its prefix.
  29  */
  30 static inline unsigned long kvm_s390_real_to_abs(struct kvm_vcpu *vcpu,
  31                                                  unsigned long gra)
  32 {
  33         unsigned long prefix  = kvm_s390_get_prefix(vcpu);
  34
  35         if (gra < 2 * PAGE_SIZE)
  36                 gra += prefix;
  37         else if (gra >= prefix && gra < prefix + 2 * PAGE_SIZE)
  38                 gra -= prefix;
  39         return gra;
  40 }
  41
  42 /**
  43  * kvm_s390_logical_to_effective - convert guest logical to effective address
  44  * @vcpu: guest virtual cpu
  45  * @ga: guest logical address
  46  *
  47  * Convert a guest vcpu logical address to a guest vcpu effective address by
  48  * applying the rules of the vcpu's addressing mode defined by PSW bits 31
  49  * and 32 (extendended/basic addressing mode).
  50  *
  51  * Depending on the vcpu's addressing mode the upper 40 bits (24 bit addressing
  52  * mode), 33 bits (31 bit addressing mode) or no bits (64 bit addressing mode)
  53  * of @ga will be zeroed and the remaining bits will be returned.
  54  */
  55 static inline unsigned long kvm_s390_logical_to_effective(struct kvm_vcpu *vcpu,
  56                                                           unsigned long ga)
  57 {
  58         psw_t *psw = &vcpu->arch.sie_block->gpsw;
  59
  60         if (psw_bits(*psw).eaba == PSW_AMODE_64BIT)
  61                 return ga;
  62         if (psw_bits(*psw).eaba == PSW_AMODE_31BIT)
  63                 return ga & ((1UL << 31) - 1);
  64         return ga & ((1UL << 24) - 1);
  65 }
  66
  67 /*
  68  * put_guest_lc, read_guest_lc and write_guest_lc are guest access functions
  69  * which shall only be used to access the lowcore of a vcpu.
  70  * These functions should be used for e.g. interrupt handlers where no
  71  * guest memory access protection facilities, like key or low address
  72  * protection, are applicable.
  73  * At a later point guest vcpu lowcore access should happen via pinned
  74  * prefix pages, so that these pages can be accessed directly via the
  75  * kernel mapping. All of these *_lc functions can be removed then.
  76  */
  77
  78 /**
  79  * put_guest_lc - write a simple variable to a guest vcpu's lowcore
  80  * @vcpu: virtual cpu
  81  * @x: value to copy to guest
  82  * @gra: vcpu's destination guest real address
  83  *
  84  * Copies a simple value from kernel space to a guest vcpu's lowcore.
  85  * The size of the variable may be 1, 2, 4 or 8 bytes. The destination
  86  * must be located in the vcpu's lowcore. Otherwise the result is undefined.
  87  *
  88  * Returns zero on success or -EFAULT on error.
  89  *
  90  * Note: an error indicates that either the kernel is out of memory or
  91  *       the guest memory mapping is broken. In any case the best solution
  92  *       would be to terminate the guest.
  93  *       It is wrong to inject a guest exception.
  94  */
  95 #define put_guest_lc(vcpu, x, gra)                              \
  96 ({                                                              \
  97         struct kvm_vcpu *__vcpu = (vcpu);                       \
  98         __typeof__(*(gra)) __x = (x);                           \
  99         unsigned long __gpa;                                    \
 100                                                                 \
 101         __gpa = (unsigned long)(gra);                           \
 102         __gpa += kvm_s390_get_prefix(__vcpu);                   \
 103         kvm_write_guest(__vcpu->kvm, __gpa, &__x, sizeof(__x)); \
 104 })
 105
 106 /**
 107  * write_guest_lc - copy data from kernel space to guest vcpu's lowcore
 108  * @vcpu: virtual cpu
 109  * @gra: vcpu's source guest real address
 110  * @data: source address in kernel space
 111  * @len: number of bytes to copy
 112  *
 113  * Copy data from kernel space to guest vcpu's lowcore. The entire range must
 114  * be located within the vcpu's lowcore, otherwise the result is undefined.
 115  *
 116  * Returns zero on success or -EFAULT on error.
 117  *
 118  * Note: an error indicates that either the kernel is out of memory or
 119  *       the guest memory mapping is broken. In any case the best solution
 120  *       would be to terminate the guest.
 121  *       It is wrong to inject a guest exception.
 122  */
 123 static inline __must_check
 124 int write_guest_lc(struct kvm_vcpu *vcpu, unsigned long gra, void *data,
 125                    unsigned long len)
 126 {
 127         unsigned long gpa = gra + kvm_s390_get_prefix(vcpu);
 128
 129         return kvm_write_guest(vcpu->kvm, gpa, data, len);
 130 }
 131
 132 /**
 133  * read_guest_lc - copy data from guest vcpu's lowcore to kernel space
 134  * @vcpu: virtual cpu
 135  * @gra: vcpu's source guest real address
 136  * @data: destination address in kernel space
 137  * @len: number of bytes to copy
 138  *
 139  * Copy data from guest vcpu's lowcore to kernel space. The entire range must
 140  * be located within the vcpu's lowcore, otherwise the result is undefined.
 141  *
 142  * Returns zero on success or -EFAULT on error.
 143  *
 144  * Note: an error indicates that either the kernel is out of memory or
 145  *       the guest memory mapping is broken. In any case the best solution
 146  *       would be to terminate the guest.
 147  *       It is wrong to inject a guest exception.
 148  */
 149 static inline __must_check
 150 int read_guest_lc(struct kvm_vcpu *vcpu, unsigned long gra, void *data,
 151                   unsigned long len)
 152 {
 153         unsigned long gpa = gra + kvm_s390_get_prefix(vcpu);
 154
 155         return kvm_read_guest(vcpu->kvm, gpa, data, len);
 156 }
 157
 158 int guest_translate_address(struct kvm_vcpu *vcpu, unsigned long gva,
 159                             unsigned long *gpa, int write);
 160
 161 int access_guest(struct kvm_vcpu *vcpu, unsigned long ga, void *data,
 162                  unsigned long len, int write);
 163
 164 int access_guest_real(struct kvm_vcpu *vcpu, unsigned long gra,
 165                       void *data, unsigned long len, int write);
 166
 167 /**
 168  * write_guest - copy data from kernel space to guest space
 169  * @vcpu: virtual cpu
 170  * @ga: guest address
 171  * @data: source address in kernel space
 172  * @len: number of bytes to copy
 173  *
 174  * Copy @len bytes from @data (kernel space) to @ga (guest address).
 175  * In order to copy data to guest space the PSW of the vcpu is inspected:
 176  * If DAT is off data will be copied to guest real or absolute memory.
 177  * If DAT is on data will be copied to the address space as specified by
 178  * the address space bits of the PSW:
 179  * Primary, secondory or home space (access register mode is currently not
 180  * implemented).
 181  * The addressing mode of the PSW is also inspected, so that address wrap
 182  * around is taken into account for 24-, 31- and 64-bit addressing mode,
 183  * if the to be copied data crosses page boundaries in guest address space.
 184  * In addition also low address and DAT protection are inspected before
 185  * copying any data (key protection is currently not implemented).
 186  *
 187  * This function modifies the 'struct kvm_s390_pgm_info pgm' member of @vcpu.
 188  * In case of an access exception (e.g. protection exception) pgm will contain
 189  * all data necessary so that a subsequent call to 'kvm_s390_inject_prog_vcpu()'
 190  * will inject a correct exception into the guest.
 191  * If no access exception happened, the contents of pgm are undefined when
 192  * this function returns.
 193  *
 194  * Returns:  - zero on success
 195  *           - a negative value if e.g. the guest mapping is broken or in
 196  *             case of out-of-memory. In this case the contents of pgm are
 197  *             undefined. Also parts of @data may have been copied to guest
 198  *             space.
 199  *           - a positive value if an access exception happened. In this case
 200  *             the returned value is the program interruption code and the
 201  *             contents of pgm may be used to inject an exception into the
 202  *             guest. No data has been copied to guest space.
 203  *
 204  * Note: in case an access exception is recognized no data has been copied to
 205  *       guest space (this is also true, if the to be copied data would cross
 206  *       one or more page boundaries in guest space).
 207  *       Therefore this function may be used for nullifying and suppressing
 208  *       instruction emulation.
 209  *       It may also be used for terminating instructions, if it is undefined
 210  *       if data has been changed in guest space in case of an exception.
 211  */
 212 static inline __must_check
 213 int write_guest(struct kvm_vcpu *vcpu, unsigned long ga, void *data,
 214                 unsigned long len)
 215 {
 216         return access_guest(vcpu, ga, data, len, 1);
 217 }
 218
 219 /**
 220  * read_guest - copy data from guest space to kernel space
 221  * @vcpu: virtual cpu
 222  * @ga: guest address
 223  * @data: destination address in kernel space
 224  * @len: number of bytes to copy
 225  *
 226  * Copy @len bytes from @ga (guest address) to @data (kernel space).
 227  *
 228  * The behaviour of read_guest is identical to write_guest, except that
 229  * data will be copied from guest space to kernel space.
 230  */
 231 static inline __must_check
 232 int read_guest(struct kvm_vcpu *vcpu, unsigned long ga, void *data,
 233                unsigned long len)
 234 {
 235         return access_guest(vcpu, ga, data, len, 0);
 236 }
 237
 238 /**
 239  * write_guest_abs - copy data from kernel space to guest space absolute
 240  * @vcpu: virtual cpu
 241  * @gpa: guest physical (absolute) address
 242  * @data: source address in kernel space
 243  * @len: number of bytes to copy
 244  *
 245  * Copy @len bytes from @data (kernel space) to @gpa (guest absolute address).
 246  * It is up to the caller to ensure that the entire guest memory range is
 247  * valid memory before calling this function.
 248  * Guest low address and key protection are not checked.
 249  *
 250  * Returns zero on success or -EFAULT on error.
 251  *
 252  * If an error occurs data may have been copied partially to guest memory.
 253  */
 254 static inline __must_check
 255 int write_guest_abs(struct kvm_vcpu *vcpu, unsigned long gpa, void *data,
 256                     unsigned long len)
 257 {
 258         return kvm_write_guest(vcpu->kvm, gpa, data, len);
 259 }
 260
 261 /**
 262  * read_guest_abs - copy data from guest space absolute to kernel space
 263  * @vcpu: virtual cpu
 264  * @gpa: guest physical (absolute) address
 265  * @data: destination address in kernel space
 266  * @len: number of bytes to copy
 267  *
 268  * Copy @len bytes from @gpa (guest absolute address) to @data (kernel space).
 269  * It is up to the caller to ensure that the entire guest memory range is
 270  * valid memory before calling this function.
 271  * Guest key protection is not checked.
 272  *
 273  * Returns zero on success or -EFAULT on error.
 274  *
 275  * If an error occurs data may have been copied partially to kernel space.
 276  */
 277 static inline __must_check
 278 int read_guest_abs(struct kvm_vcpu *vcpu, unsigned long gpa, void *data,
 279                    unsigned long len)
 280 {
 281         return kvm_read_guest(vcpu->kvm, gpa, data, len);
 282 }
 283
 284 /**
 285  * write_guest_real - copy data from kernel space to guest space real
 286  * @vcpu: virtual cpu
 287  * @gra: guest real address
 288  * @data: source address in kernel space
 289  * @len: number of bytes to copy
 290  *
 291  * Copy @len bytes from @data (kernel space) to @gra (guest real address).
 292  * It is up to the caller to ensure that the entire guest memory range is
 293  * valid memory before calling this function.
 294  * Guest low address and key protection are not checked.
 295  *
 296  * Returns zero on success or -EFAULT on error.
 297  *
 298  * If an error occurs data may have been copied partially to guest memory.
 299  */
 300 static inline __must_check
 301 int write_guest_real(struct kvm_vcpu *vcpu, unsigned long gra, void *data,
 302                      unsigned long len)
 303 {
 304         return access_guest_real(vcpu, gra, data, len, 1);
 305 }
 306
 307 /**
 308  * read_guest_real - copy data from guest space real to kernel space
 309  * @vcpu: virtual cpu
 310  * @gra: guest real address
 311  * @data: destination address in kernel space
 312  * @len: number of bytes to copy
 313  *
 314  * Copy @len bytes from @gra (guest real address) to @data (kernel space).
 315  * It is up to the caller to ensure that the entire guest memory range is
 316  * valid memory before calling this function.
 317  * Guest key protection is not checked.
 318  *
 319  * Returns zero on success or -EFAULT on error.
 320  *
 321  * If an error occurs data may have been copied partially to kernel space.
 322  */
 323 static inline __must_check
 324 int read_guest_real(struct kvm_vcpu *vcpu, unsigned long gra, void *data,
 325                     unsigned long len)
 326 {
 327         return access_guest_real(vcpu, gra, data, len, 0);
 328 }
 329
 330 int ipte_lock_held(struct kvm_vcpu *vcpu);
 331 int kvm_s390_check_low_addr_protection(struct kvm_vcpu *vcpu, unsigned long ga);
 332
 333 #endif /* __KVM_S390_GACCESS_H */