arch/x86/kvm/xen.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Copyright © 2019 Oracle and/or its affiliates. All rights reserved.
   4  * Copyright © 2020 Amazon.com, Inc. or its affiliates. All Rights Reserved.
   5  *
   6  * KVM Xen emulation
   7  */
   8
   9 #include "x86.h"
  10 #include "xen.h"
  11 #include "hyperv.h"
  12
  13 #include <linux/kvm_host.h>
  14
  15 #include <trace/events/kvm.h>
  16 #include <xen/interface/xen.h>
  17
  18 #include "trace.h"
  19
  20 DEFINE_STATIC_KEY_DEFERRED_FALSE(kvm_xen_enabled, HZ);
  21
  22 static int kvm_xen_shared_info_init(struct kvm *kvm, gfn_t gfn)
  23 {
  24         gpa_t gpa = gfn_to_gpa(gfn);
  25         int wc_ofs, sec_hi_ofs;
  26         int ret;
  27         int idx = srcu_read_lock(&kvm->srcu);
  28
  29         ret = kvm_gfn_to_hva_cache_init(kvm, &kvm->arch.xen.shinfo_cache,
  30                                         gpa, PAGE_SIZE);
  31         if (ret)
  32                 goto out;
  33
  34         kvm->arch.xen.shinfo_set = true;
  35
  36         /* Paranoia checks on the 32-bit struct layout */
  37         BUILD_BUG_ON(offsetof(struct compat_shared_info, wc) != 0x900);
  38         BUILD_BUG_ON(offsetof(struct compat_shared_info, arch.wc_sec_hi) != 0x924);
  39         BUILD_BUG_ON(offsetof(struct pvclock_vcpu_time_info, version) != 0);
  40
  41         /* 32-bit location by default */
  42         wc_ofs = offsetof(struct compat_shared_info, wc);
  43         sec_hi_ofs = offsetof(struct compat_shared_info, arch.wc_sec_hi);
  44
  45 #ifdef CONFIG_X86_64
  46         /* Paranoia checks on the 64-bit struct layout */
  47         BUILD_BUG_ON(offsetof(struct shared_info, wc) != 0xc00);
  48         BUILD_BUG_ON(offsetof(struct shared_info, wc_sec_hi) != 0xc0c);
  49
  50         if (kvm->arch.xen.long_mode) {
  51                 wc_ofs = offsetof(struct shared_info, wc);
  52                 sec_hi_ofs = offsetof(struct shared_info, wc_sec_hi);
  53         }
  54 #endif
  55
  56         kvm_write_wall_clock(kvm, gpa + wc_ofs, sec_hi_ofs - wc_ofs);
  57         kvm_make_all_cpus_request(kvm, KVM_REQ_MASTERCLOCK_UPDATE);
  58
  59 out:
  60         srcu_read_unlock(&kvm->srcu, idx);
  61         return ret;
  62 }
  63
  64 int __kvm_xen_has_interrupt(struct kvm_vcpu *v)
  65 {
  66         u8 rc = 0;
  67
  68         /*
  69          * If the global upcall vector (HVMIRQ_callback_vector) is set and
  70          * the vCPU's evtchn_upcall_pending flag is set, the IRQ is pending.
  71          */
  72         struct gfn_to_hva_cache *ghc = &v->arch.xen.vcpu_info_cache;
  73         struct kvm_memslots *slots = kvm_memslots(v->kvm);
  74         unsigned int offset = offsetof(struct vcpu_info, evtchn_upcall_pending);
  75
  76         /* No need for compat handling here */
  77         BUILD_BUG_ON(offsetof(struct vcpu_info, evtchn_upcall_pending) !=
  78                      offsetof(struct compat_vcpu_info, evtchn_upcall_pending));
  79         BUILD_BUG_ON(sizeof(rc) !=
  80                      sizeof(((struct vcpu_info *)0)->evtchn_upcall_pending));
  81         BUILD_BUG_ON(sizeof(rc) !=
  82                      sizeof(((struct compat_vcpu_info *)0)->evtchn_upcall_pending));
  83
  84         /*
  85          * For efficiency, this mirrors the checks for using the valid
  86          * cache in kvm_read_guest_offset_cached(), but just uses
  87          * __get_user() instead. And falls back to the slow path.
  88          */
  89         if (likely(slots->generation == ghc->generation &&
  90                    !kvm_is_error_hva(ghc->hva) && ghc->memslot)) {
  91                 /* Fast path */
  92                 __get_user(rc, (u8 __user *)ghc->hva + offset);
  93         } else {
  94                 /* Slow path */
  95                 kvm_read_guest_offset_cached(v->kvm, ghc, &rc, offset,
  96                                              sizeof(rc));
  97         }
  98
  99         return rc;
 100 }
 101
 102 int kvm_xen_hvm_set_attr(struct kvm *kvm, struct kvm_xen_hvm_attr *data)
 103 {
 104         int r = -ENOENT;
 105
 106         mutex_lock(&kvm->lock);
 107
 108         switch (data->type) {
 109         case KVM_XEN_ATTR_TYPE_LONG_MODE:
 110                 if (!IS_ENABLED(CONFIG_64BIT) && data->u.long_mode) {
 111                         r = -EINVAL;
 112                 } else {
 113                         kvm->arch.xen.long_mode = !!data->u.long_mode;
 114                         r = 0;
 115                 }
 116                 break;
 117
 118         case KVM_XEN_ATTR_TYPE_SHARED_INFO:
 119                 if (data->u.shared_info.gfn == GPA_INVALID) {
 120                         kvm->arch.xen.shinfo_set = false;
 121                         r = 0;
 122                         break;
 123                 }
 124                 r = kvm_xen_shared_info_init(kvm, data->u.shared_info.gfn);
 125                 break;
 126
 127
 128         case KVM_XEN_ATTR_TYPE_UPCALL_VECTOR:
 129                 if (data->u.vector && data->u.vector < 0x10)
 130                         r = -EINVAL;
 131                 else {
 132                         kvm->arch.xen.upcall_vector = data->u.vector;
 133                         r = 0;
 134                 }
 135                 break;
 136
 137         default:
 138                 break;
 139         }
 140
 141         mutex_unlock(&kvm->lock);
 142         return r;
 143 }
 144
 145 int kvm_xen_hvm_get_attr(struct kvm *kvm, struct kvm_xen_hvm_attr *data)
 146 {
 147         int r = -ENOENT;
 148
 149         mutex_lock(&kvm->lock);
 150
 151         switch (data->type) {
 152         case KVM_XEN_ATTR_TYPE_LONG_MODE:
 153                 data->u.long_mode = kvm->arch.xen.long_mode;
 154                 r = 0;
 155                 break;
 156
 157         case KVM_XEN_ATTR_TYPE_SHARED_INFO:
 158                 if (kvm->arch.xen.shinfo_set)
 159                         data->u.shared_info.gfn = gpa_to_gfn(kvm->arch.xen.shinfo_cache.gpa);
 160                 else
 161                         data->u.shared_info.gfn = GPA_INVALID;
 162                 r = 0;
 163                 break;
 164
 165         case KVM_XEN_ATTR_TYPE_UPCALL_VECTOR:
 166                 data->u.vector = kvm->arch.xen.upcall_vector;
 167                 r = 0;
 168                 break;
 169
 170         default:
 171                 break;
 172         }
 173
 174         mutex_unlock(&kvm->lock);
 175         return r;
 176 }
 177
 178 int kvm_xen_vcpu_set_attr(struct kvm_vcpu *vcpu, struct kvm_xen_vcpu_attr *data)
 179 {
 180         int idx, r = -ENOENT;
 181
 182         mutex_lock(&vcpu->kvm->lock);
 183         idx = srcu_read_lock(&vcpu->kvm->srcu);
 184
 185         switch (data->type) {
 186         case KVM_XEN_VCPU_ATTR_TYPE_VCPU_INFO:
 187                 /* No compat necessary here. */
 188                 BUILD_BUG_ON(sizeof(struct vcpu_info) !=
 189                              sizeof(struct compat_vcpu_info));
 190                 BUILD_BUG_ON(offsetof(struct vcpu_info, time) !=
 191                              offsetof(struct compat_vcpu_info, time));
 192
 193                 if (data->u.gpa == GPA_INVALID) {
 194                         vcpu->arch.xen.vcpu_info_set = false;
 195                         r = 0;
 196                         break;
 197                 }
 198
 199                 r = kvm_gfn_to_hva_cache_init(vcpu->kvm,
 200                                               &vcpu->arch.xen.vcpu_info_cache,
 201                                               data->u.gpa,
 202                                               sizeof(struct vcpu_info));
 203                 if (!r) {
 204                         vcpu->arch.xen.vcpu_info_set = true;
 205                         kvm_make_request(KVM_REQ_CLOCK_UPDATE, vcpu);
 206                 }
 207                 break;
 208
 209         case KVM_XEN_VCPU_ATTR_TYPE_VCPU_TIME_INFO:
 210                 if (data->u.gpa == GPA_INVALID) {
 211                         vcpu->arch.xen.vcpu_time_info_set = false;
 212                         r = 0;
 213                         break;
 214                 }
 215
 216                 r = kvm_gfn_to_hva_cache_init(vcpu->kvm,
 217                                               &vcpu->arch.xen.vcpu_time_info_cache,
 218                                               data->u.gpa,
 219                                               sizeof(struct pvclock_vcpu_time_info));
 220                 if (!r) {
 221                         vcpu->arch.xen.vcpu_time_info_set = true;
 222                         kvm_make_request(KVM_REQ_CLOCK_UPDATE, vcpu);
 223                 }
 224                 break;
 225
 226         default:
 227                 break;
 228         }
 229
 230         srcu_read_unlock(&vcpu->kvm->srcu, idx);
 231         mutex_unlock(&vcpu->kvm->lock);
 232         return r;
 233 }
 234
 235 int kvm_xen_vcpu_get_attr(struct kvm_vcpu *vcpu, struct kvm_xen_vcpu_attr *data)
 236 {
 237         int r = -ENOENT;
 238
 239         mutex_lock(&vcpu->kvm->lock);
 240
 241         switch (data->type) {
 242         case KVM_XEN_VCPU_ATTR_TYPE_VCPU_INFO:
 243                 if (vcpu->arch.xen.vcpu_info_set)
 244                         data->u.gpa = vcpu->arch.xen.vcpu_info_cache.gpa;
 245                 else
 246                         data->u.gpa = GPA_INVALID;
 247                 r = 0;
 248                 break;
 249
 250         case KVM_XEN_VCPU_ATTR_TYPE_VCPU_TIME_INFO:
 251                 if (vcpu->arch.xen.vcpu_time_info_set)
 252                         data->u.gpa = vcpu->arch.xen.vcpu_time_info_cache.gpa;
 253                 else
 254                         data->u.gpa = GPA_INVALID;
 255                 r = 0;
 256                 break;
 257
 258         default:
 259                 break;
 260         }
 261
 262         mutex_unlock(&vcpu->kvm->lock);
 263         return r;
 264 }
 265
 266 int kvm_xen_write_hypercall_page(struct kvm_vcpu *vcpu, u64 data)
 267 {
 268         struct kvm *kvm = vcpu->kvm;
 269         u32 page_num = data & ~PAGE_MASK;
 270         u64 page_addr = data & PAGE_MASK;
 271         bool lm = is_long_mode(vcpu);
 272
 273         /* Latch long_mode for shared_info pages etc. */
 274         vcpu->kvm->arch.xen.long_mode = lm;
 275
 276         /*
 277          * If Xen hypercall intercept is enabled, fill the hypercall
 278          * page with VMCALL/VMMCALL instructions since that's what
 279          * we catch. Else the VMM has provided the hypercall pages
 280          * with instructions of its own choosing, so use those.
 281          */
 282         if (kvm_xen_hypercall_enabled(kvm)) {
 283                 u8 instructions[32];
 284                 int i;
 285
 286                 if (page_num)
 287                         return 1;
 288
 289                 /* mov imm32, %eax */
 290                 instructions[0] = 0xb8;
 291
 292                 /* vmcall / vmmcall */
 293                 kvm_x86_ops.patch_hypercall(vcpu, instructions + 5);
 294
 295                 /* ret */
 296                 instructions[8] = 0xc3;
 297
 298                 /* int3 to pad */
 299                 memset(instructions + 9, 0xcc, sizeof(instructions) - 9);
 300
 301                 for (i = 0; i < PAGE_SIZE / sizeof(instructions); i++) {
 302                         *(u32 *)&instructions[1] = i;
 303                         if (kvm_vcpu_write_guest(vcpu,
 304                                                  page_addr + (i * sizeof(instructions)),
 305                                                  instructions, sizeof(instructions)))
 306                                 return 1;
 307                 }
 308         } else {
 309                 /*
 310                  * Note, truncation is a non-issue as 'lm' is guaranteed to be
 311                  * false for a 32-bit kernel, i.e. when hva_t is only 4 bytes.
 312                  */
 313                 hva_t blob_addr = lm ? kvm->arch.xen_hvm_config.blob_addr_64
 314                                      : kvm->arch.xen_hvm_config.blob_addr_32;
 315                 u8 blob_size = lm ? kvm->arch.xen_hvm_config.blob_size_64
 316                                   : kvm->arch.xen_hvm_config.blob_size_32;
 317                 u8 *page;
 318
 319                 if (page_num >= blob_size)
 320                         return 1;
 321
 322                 blob_addr += page_num * PAGE_SIZE;
 323
 324                 page = memdup_user((u8 __user *)blob_addr, PAGE_SIZE);
 325                 if (IS_ERR(page))
 326                         return PTR_ERR(page);
 327
 328                 if (kvm_vcpu_write_guest(vcpu, page_addr, page, PAGE_SIZE)) {
 329                         kfree(page);
 330                         return 1;
 331                 }
 332         }
 333         return 0;
 334 }
 335
 336 int kvm_xen_hvm_config(struct kvm *kvm, struct kvm_xen_hvm_config *xhc)
 337 {
 338         if (xhc->flags & ~KVM_XEN_HVM_CONFIG_INTERCEPT_HCALL)
 339                 return -EINVAL;
 340
 341         /*
 342          * With hypercall interception the kernel generates its own
 343          * hypercall page so it must not be provided.
 344          */
 345         if ((xhc->flags & KVM_XEN_HVM_CONFIG_INTERCEPT_HCALL) &&
 346             (xhc->blob_addr_32 || xhc->blob_addr_64 ||
 347              xhc->blob_size_32 || xhc->blob_size_64))
 348                 return -EINVAL;
 349
 350         mutex_lock(&kvm->lock);
 351
 352         if (xhc->msr && !kvm->arch.xen_hvm_config.msr)
 353                 static_branch_inc(&kvm_xen_enabled.key);
 354         else if (!xhc->msr && kvm->arch.xen_hvm_config.msr)
 355                 static_branch_slow_dec_deferred(&kvm_xen_enabled);
 356
 357         memcpy(&kvm->arch.xen_hvm_config, xhc, sizeof(*xhc));
 358
 359         mutex_unlock(&kvm->lock);
 360         return 0;
 361 }
 362
 363 void kvm_xen_destroy_vm(struct kvm *kvm)
 364 {
 365         if (kvm->arch.xen_hvm_config.msr)
 366                 static_branch_slow_dec_deferred(&kvm_xen_enabled);
 367 }
 368
 369 static int kvm_xen_hypercall_set_result(struct kvm_vcpu *vcpu, u64 result)
 370 {
 371         kvm_rax_write(vcpu, result);
 372         return kvm_skip_emulated_instruction(vcpu);
 373 }
 374
 375 static int kvm_xen_hypercall_complete_userspace(struct kvm_vcpu *vcpu)
 376 {
 377         struct kvm_run *run = vcpu->run;
 378
 379         if (unlikely(!kvm_is_linear_rip(vcpu, vcpu->arch.xen.hypercall_rip)))
 380                 return 1;
 381
 382         return kvm_xen_hypercall_set_result(vcpu, run->xen.u.hcall.result);
 383 }
 384
 385 int kvm_xen_hypercall(struct kvm_vcpu *vcpu)
 386 {
 387         bool longmode;
 388         u64 input, params[6];
 389
 390         input = (u64)kvm_register_read(vcpu, VCPU_REGS_RAX);
 391
 392         /* Hyper-V hypercalls get bit 31 set in EAX */
 393         if ((input & 0x80000000) &&
 394             kvm_hv_hypercall_enabled(vcpu))
 395                 return kvm_hv_hypercall(vcpu);
 396
 397         longmode = is_64_bit_mode(vcpu);
 398         if (!longmode) {
 399                 params[0] = (u32)kvm_rbx_read(vcpu);
 400                 params[1] = (u32)kvm_rcx_read(vcpu);
 401                 params[2] = (u32)kvm_rdx_read(vcpu);
 402                 params[3] = (u32)kvm_rsi_read(vcpu);
 403                 params[4] = (u32)kvm_rdi_read(vcpu);
 404                 params[5] = (u32)kvm_rbp_read(vcpu);
 405         }
 406 #ifdef CONFIG_X86_64
 407         else {
 408                 params[0] = (u64)kvm_rdi_read(vcpu);
 409                 params[1] = (u64)kvm_rsi_read(vcpu);
 410                 params[2] = (u64)kvm_rdx_read(vcpu);
 411                 params[3] = (u64)kvm_r10_read(vcpu);
 412                 params[4] = (u64)kvm_r8_read(vcpu);
 413                 params[5] = (u64)kvm_r9_read(vcpu);
 414         }
 415 #endif
 416         trace_kvm_xen_hypercall(input, params[0], params[1], params[2],
 417                                 params[3], params[4], params[5]);
 418
 419         vcpu->run->exit_reason = KVM_EXIT_XEN;
 420         vcpu->run->xen.type = KVM_EXIT_XEN_HCALL;
 421         vcpu->run->xen.u.hcall.longmode = longmode;
 422         vcpu->run->xen.u.hcall.cpl = kvm_x86_ops.get_cpl(vcpu);
 423         vcpu->run->xen.u.hcall.input = input;
 424         vcpu->run->xen.u.hcall.params[0] = params[0];
 425         vcpu->run->xen.u.hcall.params[1] = params[1];
 426         vcpu->run->xen.u.hcall.params[2] = params[2];
 427         vcpu->run->xen.u.hcall.params[3] = params[3];
 428         vcpu->run->xen.u.hcall.params[4] = params[4];
 429         vcpu->run->xen.u.hcall.params[5] = params[5];
 430         vcpu->arch.xen.hypercall_rip = kvm_get_linear_rip(vcpu);
 431         vcpu->arch.complete_userspace_io =
 432                 kvm_xen_hypercall_complete_userspace;
 433
 434         return 0;
 435 }