drivers/hv/hv.c

   1 /*
   2  * Copyright (c) 2009, Microsoft Corporation.
   3  *
   4  * This program is free software; you can redistribute it and/or modify it
   5  * under the terms and conditions of the GNU General Public License,
   6  * version 2, as published by the Free Software Foundation.
   7  *
   8  * This program is distributed in the hope it will be useful, but WITHOUT
   9  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  10  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
  11  * more details.
  12  *
  13  * You should have received a copy of the GNU General Public License along with
  14  * this program; if not, write to the Free Software Foundation, Inc., 59 Temple
  15  * Place - Suite 330, Boston, MA 02111-1307 USA.
  16  *
  17  * Authors:
  18  *   Haiyang Zhang <haiyangz@microsoft.com>
  19  *   Hank Janssen  <hjanssen@microsoft.com>
  20  *
  21  */
  22 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  23
  24 #include <linux/kernel.h>
  25 #include <linux/mm.h>
  26 #include <linux/slab.h>
  27 #include <linux/vmalloc.h>
  28 #include <linux/hyperv.h>
  29 #include <linux/version.h>
  30 #include <linux/interrupt.h>
  31 #include <linux/clockchips.h>
  32 #include <asm/hyperv.h>
  33 #include <asm/mshyperv.h>
  34 #include "hyperv_vmbus.h"
  35
  36 /* The one and only */
  37 struct hv_context hv_context = {
  38         .synic_initialized      = false,
  39         .hypercall_page         = NULL,
  40 };
  41
  42 #define HV_TIMER_FREQUENCY (10 * 1000 * 1000) /* 100ns period */
  43 #define HV_MAX_MAX_DELTA_TICKS 0xffffffff
  44 #define HV_MIN_DELTA_TICKS 1
  45
  46 /*
  47  * query_hypervisor_info - Get version info of the windows hypervisor
  48  */
  49 unsigned int host_info_eax;
  50 unsigned int host_info_ebx;
  51 unsigned int host_info_ecx;
  52 unsigned int host_info_edx;
  53
  54 static int query_hypervisor_info(void)
  55 {
  56         unsigned int eax;
  57         unsigned int ebx;
  58         unsigned int ecx;
  59         unsigned int edx;
  60         unsigned int max_leaf;
  61         unsigned int op;
  62
  63         /*
  64         * Its assumed that this is called after confirming that Viridian
  65         * is present. Query id and revision.
  66         */
  67         eax = 0;
  68         ebx = 0;
  69         ecx = 0;
  70         edx = 0;
  71         op = HVCPUID_VENDOR_MAXFUNCTION;
  72         cpuid(op, &eax, &ebx, &ecx, &edx);
  73
  74         max_leaf = eax;
  75
  76         if (max_leaf >= HVCPUID_VERSION) {
  77                 eax = 0;
  78                 ebx = 0;
  79                 ecx = 0;
  80                 edx = 0;
  81                 op = HVCPUID_VERSION;
  82                 cpuid(op, &eax, &ebx, &ecx, &edx);
  83                 host_info_eax = eax;
  84                 host_info_ebx = ebx;
  85                 host_info_ecx = ecx;
  86                 host_info_edx = edx;
  87         }
  88         return max_leaf;
  89 }
  90
  91 /*
  92  * hv_do_hypercall- Invoke the specified hypercall
  93  */
  94 u64 hv_do_hypercall(u64 control, void *input, void *output)
  95 {
  96         u64 input_address = (input) ? virt_to_phys(input) : 0;
  97         u64 output_address = (output) ? virt_to_phys(output) : 0;
  98         void *hypercall_page = hv_context.hypercall_page;
  99 #ifdef CONFIG_X86_64
 100         u64 hv_status = 0;
 101
 102         if (!hypercall_page)
 103                 return (u64)ULLONG_MAX;
 104
 105         __asm__ __volatile__("mov %0, %%r8" : : "r" (output_address) : "r8");
 106         __asm__ __volatile__("call *%3" : "=a" (hv_status) :
 107                              "c" (control), "d" (input_address),
 108                              "m" (hypercall_page));
 109
 110         return hv_status;
 111
 112 #else
 113
 114         u32 control_hi = control >> 32;
 115         u32 control_lo = control & 0xFFFFFFFF;
 116         u32 hv_status_hi = 1;
 117         u32 hv_status_lo = 1;
 118         u32 input_address_hi = input_address >> 32;
 119         u32 input_address_lo = input_address & 0xFFFFFFFF;
 120         u32 output_address_hi = output_address >> 32;
 121         u32 output_address_lo = output_address & 0xFFFFFFFF;
 122
 123         if (!hypercall_page)
 124                 return (u64)ULLONG_MAX;
 125
 126         __asm__ __volatile__ ("call *%8" : "=d"(hv_status_hi),
 127                               "=a"(hv_status_lo) : "d" (control_hi),
 128                               "a" (control_lo), "b" (input_address_hi),
 129                               "c" (input_address_lo), "D"(output_address_hi),
 130                               "S"(output_address_lo), "m" (hypercall_page));
 131
 132         return hv_status_lo | ((u64)hv_status_hi << 32);
 133 #endif /* !x86_64 */
 134 }
 135 EXPORT_SYMBOL_GPL(hv_do_hypercall);
 136
 137 #ifdef CONFIG_X86_64
 138 static u64 read_hv_clock_tsc(struct clocksource *arg)
 139 {
 140         u64 current_tick;
 141         struct ms_hyperv_tsc_page *tsc_pg = hv_context.tsc_page;
 142
 143         if (tsc_pg->tsc_sequence != 0) {
 144                 /*
 145                  * Use the tsc page to compute the value.
 146                  */
 147
 148                 while (1) {
 149                         u64 tmp;
 150                         u32 sequence = tsc_pg->tsc_sequence;
 151                         u64 cur_tsc;
 152                         u64 scale = tsc_pg->tsc_scale;
 153                         s64 offset = tsc_pg->tsc_offset;
 154
 155                         rdtscll(cur_tsc);
 156                         /* current_tick = ((cur_tsc *scale) >> 64) + offset */
 157                         asm("mulq %3"
 158                                 : "=d" (current_tick), "=a" (tmp)
 159                                 : "a" (cur_tsc), "r" (scale));
 160
 161                         current_tick += offset;
 162                         if (tsc_pg->tsc_sequence == sequence)
 163                                 return current_tick;
 164
 165                         if (tsc_pg->tsc_sequence != 0)
 166                                 continue;
 167                         /*
 168                          * Fallback using MSR method.
 169                          */
 170                         break;
 171                 }
 172         }
 173         rdmsrl(HV_X64_MSR_TIME_REF_COUNT, current_tick);
 174         return current_tick;
 175 }
 176
 177 static struct clocksource hyperv_cs_tsc = {
 178                 .name           = "hyperv_clocksource_tsc_page",
 179                 .rating         = 425,
 180                 .read           = read_hv_clock_tsc,
 181                 .mask           = CLOCKSOURCE_MASK(64),
 182                 .flags          = CLOCK_SOURCE_IS_CONTINUOUS,
 183 };
 184 #endif
 185
 186
 187 /*
 188  * hv_init - Main initialization routine.
 189  *
 190  * This routine must be called before any other routines in here are called
 191  */
 192 int hv_init(void)
 193 {
 194         int max_leaf;
 195         union hv_x64_msr_hypercall_contents hypercall_msr;
 196         void *virtaddr = NULL;
 197
 198         memset(hv_context.synic_event_page, 0, sizeof(void *) * NR_CPUS);
 199         memset(hv_context.synic_message_page, 0,
 200                sizeof(void *) * NR_CPUS);
 201         memset(hv_context.post_msg_page, 0,
 202                sizeof(void *) * NR_CPUS);
 203         memset(hv_context.vp_index, 0,
 204                sizeof(int) * NR_CPUS);
 205         memset(hv_context.event_dpc, 0,
 206                sizeof(void *) * NR_CPUS);
 207         memset(hv_context.msg_dpc, 0,
 208                sizeof(void *) * NR_CPUS);
 209         memset(hv_context.clk_evt, 0,
 210                sizeof(void *) * NR_CPUS);
 211
 212         max_leaf = query_hypervisor_info();
 213
 214         /*
 215          * Write our OS ID.
 216          */
 217         hv_context.guestid = generate_guest_id(0, LINUX_VERSION_CODE, 0);
 218         wrmsrl(HV_X64_MSR_GUEST_OS_ID, hv_context.guestid);
 219
 220         /* See if the hypercall page is already set */
 221         rdmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64);
 222
 223         virtaddr = __vmalloc(PAGE_SIZE, GFP_KERNEL, PAGE_KERNEL_EXEC);
 224
 225         if (!virtaddr)
 226                 goto cleanup;
 227
 228         hypercall_msr.enable = 1;
 229
 230         hypercall_msr.guest_physical_address = vmalloc_to_pfn(virtaddr);
 231         wrmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64);
 232
 233         /* Confirm that hypercall page did get setup. */
 234         hypercall_msr.as_uint64 = 0;
 235         rdmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64);
 236
 237         if (!hypercall_msr.enable)
 238                 goto cleanup;
 239
 240         hv_context.hypercall_page = virtaddr;
 241
 242 #ifdef CONFIG_X86_64
 243         if (ms_hyperv.features & HV_X64_MSR_REFERENCE_TSC_AVAILABLE) {
 244                 union hv_x64_msr_hypercall_contents tsc_msr;
 245                 void *va_tsc;
 246
 247                 va_tsc = __vmalloc(PAGE_SIZE, GFP_KERNEL, PAGE_KERNEL);
 248                 if (!va_tsc)
 249                         goto cleanup;
 250                 hv_context.tsc_page = va_tsc;
 251
 252                 rdmsrl(HV_X64_MSR_REFERENCE_TSC, tsc_msr.as_uint64);
 253
 254                 tsc_msr.enable = 1;
 255                 tsc_msr.guest_physical_address = vmalloc_to_pfn(va_tsc);
 256
 257                 wrmsrl(HV_X64_MSR_REFERENCE_TSC, tsc_msr.as_uint64);
 258                 clocksource_register_hz(&hyperv_cs_tsc, NSEC_PER_SEC/100);
 259         }
 260 #endif
 261         return 0;
 262
 263 cleanup:
 264         if (virtaddr) {
 265                 if (hypercall_msr.enable) {
 266                         hypercall_msr.as_uint64 = 0;
 267                         wrmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64);
 268                 }
 269
 270                 vfree(virtaddr);
 271         }
 272
 273         return -ENOTSUPP;
 274 }
 275
 276 /*
 277  * hv_cleanup - Cleanup routine.
 278  *
 279  * This routine is called normally during driver unloading or exiting.
 280  */
 281 void hv_cleanup(bool crash)
 282 {
 283         union hv_x64_msr_hypercall_contents hypercall_msr;
 284
 285         /* Reset our OS id */
 286         wrmsrl(HV_X64_MSR_GUEST_OS_ID, 0);
 287
 288         if (hv_context.hypercall_page) {
 289                 hypercall_msr.as_uint64 = 0;
 290                 wrmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64);
 291                 if (!crash)
 292                         vfree(hv_context.hypercall_page);
 293                 hv_context.hypercall_page = NULL;
 294         }
 295
 296 #ifdef CONFIG_X86_64
 297         /*
 298          * Cleanup the TSC page based CS.
 299          */
 300         if (ms_hyperv.features & HV_X64_MSR_REFERENCE_TSC_AVAILABLE) {
 301                 /*
 302                  * Crash can happen in an interrupt context and unregistering
 303                  * a clocksource is impossible and redundant in this case.
 304                  */
 305                 if (!oops_in_progress) {
 306                         clocksource_change_rating(&hyperv_cs_tsc, 10);
 307                         clocksource_unregister(&hyperv_cs_tsc);
 308                 }
 309
 310                 hypercall_msr.as_uint64 = 0;
 311                 wrmsrl(HV_X64_MSR_REFERENCE_TSC, hypercall_msr.as_uint64);
 312                 if (!crash)
 313                         vfree(hv_context.tsc_page);
 314                 hv_context.tsc_page = NULL;
 315         }
 316 #endif
 317 }
 318
 319 /*
 320  * hv_post_message - Post a message using the hypervisor message IPC.
 321  *
 322  * This involves a hypercall.
 323  */
 324 int hv_post_message(union hv_connection_id connection_id,
 325                   enum hv_message_type message_type,
 326                   void *payload, size_t payload_size)
 327 {
 328
 329         struct hv_input_post_message *aligned_msg;
 330         u64 status;
 331
 332         if (payload_size > HV_MESSAGE_PAYLOAD_BYTE_COUNT)
 333                 return -EMSGSIZE;
 334
 335         aligned_msg = (struct hv_input_post_message *)
 336                         hv_context.post_msg_page[get_cpu()];
 337
 338         aligned_msg->connectionid = connection_id;
 339         aligned_msg->reserved = 0;
 340         aligned_msg->message_type = message_type;
 341         aligned_msg->payload_size = payload_size;
 342         memcpy((void *)aligned_msg->payload, payload, payload_size);
 343
 344         status = hv_do_hypercall(HVCALL_POST_MESSAGE, aligned_msg, NULL);
 345
 346         put_cpu();
 347         return status & 0xFFFF;
 348 }
 349
 350 static int hv_ce_set_next_event(unsigned long delta,
 351                                 struct clock_event_device *evt)
 352 {
 353         u64 current_tick;
 354
 355         WARN_ON(!clockevent_state_oneshot(evt));
 356
 357         rdmsrl(HV_X64_MSR_TIME_REF_COUNT, current_tick);
 358         current_tick += delta;
 359         wrmsrl(HV_X64_MSR_STIMER0_COUNT, current_tick);
 360         return 0;
 361 }
 362
 363 static int hv_ce_shutdown(struct clock_event_device *evt)
 364 {
 365         wrmsrl(HV_X64_MSR_STIMER0_COUNT, 0);
 366         wrmsrl(HV_X64_MSR_STIMER0_CONFIG, 0);
 367
 368         return 0;
 369 }
 370
 371 static int hv_ce_set_oneshot(struct clock_event_device *evt)
 372 {
 373         union hv_timer_config timer_cfg;
 374
 375         timer_cfg.enable = 1;
 376         timer_cfg.auto_enable = 1;
 377         timer_cfg.sintx = VMBUS_MESSAGE_SINT;
 378         wrmsrl(HV_X64_MSR_STIMER0_CONFIG, timer_cfg.as_uint64);
 379
 380         return 0;
 381 }
 382
 383 static void hv_init_clockevent_device(struct clock_event_device *dev, int cpu)
 384 {
 385         dev->name = "Hyper-V clockevent";
 386         dev->features = CLOCK_EVT_FEAT_ONESHOT;
 387         dev->cpumask = cpumask_of(cpu);
 388         dev->rating = 1000;
 389         /*
 390          * Avoid settint dev->owner = THIS_MODULE deliberately as doing so will
 391          * result in clockevents_config_and_register() taking additional
 392          * references to the hv_vmbus module making it impossible to unload.
 393          */
 394
 395         dev->set_state_shutdown = hv_ce_shutdown;
 396         dev->set_state_oneshot = hv_ce_set_oneshot;
 397         dev->set_next_event = hv_ce_set_next_event;
 398 }
 399
 400
 401 int hv_synic_alloc(void)
 402 {
 403         size_t size = sizeof(struct tasklet_struct);
 404         size_t ced_size = sizeof(struct clock_event_device);
 405         int cpu;
 406
 407         hv_context.hv_numa_map = kzalloc(sizeof(struct cpumask) * nr_node_ids,
 408                                          GFP_ATOMIC);
 409         if (hv_context.hv_numa_map == NULL) {
 410                 pr_err("Unable to allocate NUMA map\n");
 411                 goto err;
 412         }
 413
 414         for_each_online_cpu(cpu) {
 415                 hv_context.event_dpc[cpu] = kmalloc(size, GFP_ATOMIC);
 416                 if (hv_context.event_dpc[cpu] == NULL) {
 417                         pr_err("Unable to allocate event dpc\n");
 418                         goto err;
 419                 }
 420                 tasklet_init(hv_context.event_dpc[cpu], vmbus_on_event, cpu);
 421
 422                 hv_context.msg_dpc[cpu] = kmalloc(size, GFP_ATOMIC);
 423                 if (hv_context.msg_dpc[cpu] == NULL) {
 424                         pr_err("Unable to allocate event dpc\n");
 425                         goto err;
 426                 }
 427                 tasklet_init(hv_context.msg_dpc[cpu], vmbus_on_msg_dpc, cpu);
 428
 429                 hv_context.clk_evt[cpu] = kzalloc(ced_size, GFP_ATOMIC);
 430                 if (hv_context.clk_evt[cpu] == NULL) {
 431                         pr_err("Unable to allocate clock event device\n");
 432                         goto err;
 433                 }
 434
 435                 hv_init_clockevent_device(hv_context.clk_evt[cpu], cpu);
 436
 437                 hv_context.synic_message_page[cpu] =
 438                         (void *)get_zeroed_page(GFP_ATOMIC);
 439
 440                 if (hv_context.synic_message_page[cpu] == NULL) {
 441                         pr_err("Unable to allocate SYNIC message page\n");
 442                         goto err;
 443                 }
 444
 445                 hv_context.synic_event_page[cpu] =
 446                         (void *)get_zeroed_page(GFP_ATOMIC);
 447
 448                 if (hv_context.synic_event_page[cpu] == NULL) {
 449                         pr_err("Unable to allocate SYNIC event page\n");
 450                         goto err;
 451                 }
 452
 453                 hv_context.post_msg_page[cpu] =
 454                         (void *)get_zeroed_page(GFP_ATOMIC);
 455
 456                 if (hv_context.post_msg_page[cpu] == NULL) {
 457                         pr_err("Unable to allocate post msg page\n");
 458                         goto err;
 459                 }
 460         }
 461
 462         return 0;
 463 err:
 464         return -ENOMEM;
 465 }
 466
 467 static void hv_synic_free_cpu(int cpu)
 468 {
 469         kfree(hv_context.event_dpc[cpu]);
 470         kfree(hv_context.msg_dpc[cpu]);
 471         kfree(hv_context.clk_evt[cpu]);
 472         if (hv_context.synic_event_page[cpu])
 473                 free_page((unsigned long)hv_context.synic_event_page[cpu]);
 474         if (hv_context.synic_message_page[cpu])
 475                 free_page((unsigned long)hv_context.synic_message_page[cpu]);
 476         if (hv_context.post_msg_page[cpu])
 477                 free_page((unsigned long)hv_context.post_msg_page[cpu]);
 478 }
 479
 480 void hv_synic_free(void)
 481 {
 482         int cpu;
 483
 484         kfree(hv_context.hv_numa_map);
 485         for_each_online_cpu(cpu)
 486                 hv_synic_free_cpu(cpu);
 487 }
 488
 489 /*
 490  * hv_synic_init - Initialize the Synthethic Interrupt Controller.
 491  *
 492  * If it is already initialized by another entity (ie x2v shim), we need to
 493  * retrieve the initialized message and event pages.  Otherwise, we create and
 494  * initialize the message and event pages.
 495  */
 496 void hv_synic_init(void *arg)
 497 {
 498         u64 version;
 499         union hv_synic_simp simp;
 500         union hv_synic_siefp siefp;
 501         union hv_synic_sint shared_sint;
 502         union hv_synic_scontrol sctrl;
 503         u64 vp_index;
 504
 505         int cpu = smp_processor_id();
 506
 507         if (!hv_context.hypercall_page)
 508                 return;
 509
 510         /* Check the version */
 511         rdmsrl(HV_X64_MSR_SVERSION, version);
 512
 513         /* Setup the Synic's message page */
 514         rdmsrl(HV_X64_MSR_SIMP, simp.as_uint64);
 515         simp.simp_enabled = 1;
 516         simp.base_simp_gpa = virt_to_phys(hv_context.synic_message_page[cpu])
 517                 >> PAGE_SHIFT;
 518
 519         wrmsrl(HV_X64_MSR_SIMP, simp.as_uint64);
 520
 521         /* Setup the Synic's event page */
 522         rdmsrl(HV_X64_MSR_SIEFP, siefp.as_uint64);
 523         siefp.siefp_enabled = 1;
 524         siefp.base_siefp_gpa = virt_to_phys(hv_context.synic_event_page[cpu])
 525                 >> PAGE_SHIFT;
 526
 527         wrmsrl(HV_X64_MSR_SIEFP, siefp.as_uint64);
 528
 529         /* Setup the shared SINT. */
 530         rdmsrl(HV_X64_MSR_SINT0 + VMBUS_MESSAGE_SINT, shared_sint.as_uint64);
 531
 532         shared_sint.as_uint64 = 0;
 533         shared_sint.vector = HYPERVISOR_CALLBACK_VECTOR;
 534         shared_sint.masked = false;
 535         shared_sint.auto_eoi = true;
 536
 537         wrmsrl(HV_X64_MSR_SINT0 + VMBUS_MESSAGE_SINT, shared_sint.as_uint64);
 538
 539         /* Enable the global synic bit */
 540         rdmsrl(HV_X64_MSR_SCONTROL, sctrl.as_uint64);
 541         sctrl.enable = 1;
 542
 543         wrmsrl(HV_X64_MSR_SCONTROL, sctrl.as_uint64);
 544
 545         hv_context.synic_initialized = true;
 546
 547         /*
 548          * Setup the mapping between Hyper-V's notion
 549          * of cpuid and Linux' notion of cpuid.
 550          * This array will be indexed using Linux cpuid.
 551          */
 552         rdmsrl(HV_X64_MSR_VP_INDEX, vp_index);
 553         hv_context.vp_index[cpu] = (u32)vp_index;
 554
 555         INIT_LIST_HEAD(&hv_context.percpu_list[cpu]);
 556
 557         /*
 558          * Register the per-cpu clockevent source.
 559          */
 560         if (ms_hyperv.features & HV_X64_MSR_SYNTIMER_AVAILABLE)
 561                 clockevents_config_and_register(hv_context.clk_evt[cpu],
 562                                                 HV_TIMER_FREQUENCY,
 563                                                 HV_MIN_DELTA_TICKS,
 564                                                 HV_MAX_MAX_DELTA_TICKS);
 565         return;
 566 }
 567
 568 /*
 569  * hv_synic_clockevents_cleanup - Cleanup clockevent devices
 570  */
 571 void hv_synic_clockevents_cleanup(void)
 572 {
 573         int cpu;
 574
 575         if (!(ms_hyperv.features & HV_X64_MSR_SYNTIMER_AVAILABLE))
 576                 return;
 577
 578         for_each_present_cpu(cpu)
 579                 clockevents_unbind_device(hv_context.clk_evt[cpu], cpu);
 580 }
 581
 582 /*
 583  * hv_synic_cleanup - Cleanup routine for hv_synic_init().
 584  */
 585 void hv_synic_cleanup(void *arg)
 586 {
 587         union hv_synic_sint shared_sint;
 588         union hv_synic_simp simp;
 589         union hv_synic_siefp siefp;
 590         union hv_synic_scontrol sctrl;
 591         int cpu = smp_processor_id();
 592
 593         if (!hv_context.synic_initialized)
 594                 return;
 595
 596         /* Turn off clockevent device */
 597         if (ms_hyperv.features & HV_X64_MSR_SYNTIMER_AVAILABLE) {
 598                 clockevents_unbind_device(hv_context.clk_evt[cpu], cpu);
 599                 hv_ce_shutdown(hv_context.clk_evt[cpu]);
 600         }
 601
 602         rdmsrl(HV_X64_MSR_SINT0 + VMBUS_MESSAGE_SINT, shared_sint.as_uint64);
 603
 604         shared_sint.masked = 1;
 605
 606         /* Need to correctly cleanup in the case of SMP!!! */
 607         /* Disable the interrupt */
 608         wrmsrl(HV_X64_MSR_SINT0 + VMBUS_MESSAGE_SINT, shared_sint.as_uint64);
 609
 610         rdmsrl(HV_X64_MSR_SIMP, simp.as_uint64);
 611         simp.simp_enabled = 0;
 612         simp.base_simp_gpa = 0;
 613
 614         wrmsrl(HV_X64_MSR_SIMP, simp.as_uint64);
 615
 616         rdmsrl(HV_X64_MSR_SIEFP, siefp.as_uint64);
 617         siefp.siefp_enabled = 0;
 618         siefp.base_siefp_gpa = 0;
 619
 620         wrmsrl(HV_X64_MSR_SIEFP, siefp.as_uint64);
 621
 622         /* Disable the global synic bit */
 623         rdmsrl(HV_X64_MSR_SCONTROL, sctrl.as_uint64);
 624         sctrl.enable = 0;
 625         wrmsrl(HV_X64_MSR_SCONTROL, sctrl.as_uint64);
 626 }