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 <asm/nospec-branch.h>
  35 #include "hyperv_vmbus.h"
  36
  37 /* The one and only */
  38 struct hv_context hv_context = {
  39         .synic_initialized      = false,
  40         .hypercall_page         = NULL,
  41 };
  42
  43 #define HV_TIMER_FREQUENCY (10 * 1000 * 1000) /* 100ns period */
  44 #define HV_MAX_MAX_DELTA_TICKS 0xffffffff
  45 #define HV_MIN_DELTA_TICKS 1
  46
  47 /*
  48  * query_hypervisor_info - Get version info of the windows hypervisor
  49  */
  50 unsigned int host_info_eax;
  51 unsigned int host_info_ebx;
  52 unsigned int host_info_ecx;
  53 unsigned int host_info_edx;
  54
  55 static int query_hypervisor_info(void)
  56 {
  57         unsigned int eax;
  58         unsigned int ebx;
  59         unsigned int ecx;
  60         unsigned int edx;
  61         unsigned int max_leaf;
  62         unsigned int op;
  63
  64         /*
  65         * Its assumed that this is called after confirming that Viridian
  66         * is present. Query id and revision.
  67         */
  68         eax = 0;
  69         ebx = 0;
  70         ecx = 0;
  71         edx = 0;
  72         op = HVCPUID_VENDOR_MAXFUNCTION;
  73         cpuid(op, &eax, &ebx, &ecx, &edx);
  74
  75         max_leaf = eax;
  76
  77         if (max_leaf >= HVCPUID_VERSION) {
  78                 eax = 0;
  79                 ebx = 0;
  80                 ecx = 0;
  81                 edx = 0;
  82                 op = HVCPUID_VERSION;
  83                 cpuid(op, &eax, &ebx, &ecx, &edx);
  84                 host_info_eax = eax;
  85                 host_info_ebx = ebx;
  86                 host_info_ecx = ecx;
  87                 host_info_edx = edx;
  88         }
  89         return max_leaf;
  90 }
  91
  92 /*
  93  * do_hypercall- Invoke the specified hypercall
  94  */
  95 static u64 do_hypercall(u64 control, void *input, void *output)
  96 {
  97         u64 input_address = (input) ? virt_to_phys(input) : 0;
  98         u64 output_address = (output) ? virt_to_phys(output) : 0;
  99         void *hypercall_page = hv_context.hypercall_page;
 100 #ifdef CONFIG_X86_64
 101         u64 hv_status = 0;
 102
 103         if (!hypercall_page)
 104                 return (u64)ULLONG_MAX;
 105
 106         __asm__ __volatile__("mov %0, %%r8" : : "r" (output_address) : "r8");
 107         __asm__ __volatile__(CALL_NOSPEC :
 108                              "=a" (hv_status) :
 109                              "c" (control), "d" (input_address),
 110                              THUNK_TARGET(hypercall_page));
 111
 112         return hv_status;
 113
 114 #else
 115
 116         u32 control_hi = control >> 32;
 117         u32 control_lo = control & 0xFFFFFFFF;
 118         u32 hv_status_hi = 1;
 119         u32 hv_status_lo = 1;
 120         u32 input_address_hi = input_address >> 32;
 121         u32 input_address_lo = input_address & 0xFFFFFFFF;
 122         u32 output_address_hi = output_address >> 32;
 123         u32 output_address_lo = output_address & 0xFFFFFFFF;
 124
 125         if (!hypercall_page)
 126                 return (u64)ULLONG_MAX;
 127
 128         __asm__ __volatile__ (CALL_NOSPEC : "=d"(hv_status_hi),
 129                               "=a"(hv_status_lo) : "d" (control_hi),
 130                               "a" (control_lo), "b" (input_address_hi),
 131                               "c" (input_address_lo), "D"(output_address_hi),
 132                               "S"(output_address_lo),
 133                               THUNK_TARGET(hypercall_page));
 134
 135         return hv_status_lo | ((u64)hv_status_hi << 32);
 136 #endif /* !x86_64 */
 137 }
 138
 139 #ifdef CONFIG_X86_64
 140 static cycle_t read_hv_clock_tsc(struct clocksource *arg)
 141 {
 142         cycle_t current_tick;
 143         struct ms_hyperv_tsc_page *tsc_pg = hv_context.tsc_page;
 144
 145         if (tsc_pg->tsc_sequence != -1) {
 146                 /*
 147                  * Use the tsc page to compute the value.
 148                  */
 149
 150                 while (1) {
 151                         cycle_t tmp;
 152                         u32 sequence = tsc_pg->tsc_sequence;
 153                         u64 cur_tsc;
 154                         u64 scale = tsc_pg->tsc_scale;
 155                         s64 offset = tsc_pg->tsc_offset;
 156
 157                         rdtscll(cur_tsc);
 158                         /* current_tick = ((cur_tsc *scale) >> 64) + offset */
 159                         asm("mulq %3"
 160                                 : "=d" (current_tick), "=a" (tmp)
 161                                 : "a" (cur_tsc), "r" (scale));
 162
 163                         current_tick += offset;
 164                         if (tsc_pg->tsc_sequence == sequence)
 165                                 return current_tick;
 166
 167                         if (tsc_pg->tsc_sequence != -1)
 168                                 continue;
 169                         /*
 170                          * Fallback using MSR method.
 171                          */
 172                         break;
 173                 }
 174         }
 175         rdmsrl(HV_X64_MSR_TIME_REF_COUNT, current_tick);
 176         return current_tick;
 177 }
 178
 179 static struct clocksource hyperv_cs_tsc = {
 180                 .name           = "hyperv_clocksource_tsc_page",
 181                 .rating         = 425,
 182                 .read           = read_hv_clock_tsc,
 183                 .mask           = CLOCKSOURCE_MASK(64),
 184                 .flags          = CLOCK_SOURCE_IS_CONTINUOUS,
 185 };
 186 #endif
 187
 188
 189 /*
 190  * hv_init - Main initialization routine.
 191  *
 192  * This routine must be called before any other routines in here are called
 193  */
 194 int hv_init(void)
 195 {
 196         int max_leaf;
 197         union hv_x64_msr_hypercall_contents hypercall_msr;
 198         void *virtaddr = NULL;
 199
 200         memset(hv_context.synic_event_page, 0, sizeof(void *) * NR_CPUS);
 201         memset(hv_context.synic_message_page, 0,
 202                sizeof(void *) * NR_CPUS);
 203         memset(hv_context.post_msg_page, 0,
 204                sizeof(void *) * NR_CPUS);
 205         memset(hv_context.vp_index, 0,
 206                sizeof(int) * NR_CPUS);
 207         memset(hv_context.event_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_RX);
 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         }
 317 #endif
 318 }
 319
 320 /*
 321  * hv_post_message - Post a message using the hypervisor message IPC.
 322  *
 323  * This involves a hypercall.
 324  */
 325 int hv_post_message(union hv_connection_id connection_id,
 326                   enum hv_message_type message_type,
 327                   void *payload, size_t payload_size)
 328 {
 329
 330         struct hv_input_post_message *aligned_msg;
 331         u16 status;
 332
 333         if (payload_size > HV_MESSAGE_PAYLOAD_BYTE_COUNT)
 334                 return -EMSGSIZE;
 335
 336         aligned_msg = (struct hv_input_post_message *)
 337                         hv_context.post_msg_page[get_cpu()];
 338
 339         aligned_msg->connectionid = connection_id;
 340         aligned_msg->reserved = 0;
 341         aligned_msg->message_type = message_type;
 342         aligned_msg->payload_size = payload_size;
 343         memcpy((void *)aligned_msg->payload, payload, payload_size);
 344
 345         status = do_hypercall(HVCALL_POST_MESSAGE, aligned_msg, NULL)
 346                 & 0xFFFF;
 347
 348         put_cpu();
 349         return status;
 350 }
 351
 352
 353 /*
 354  * hv_signal_event -
 355  * Signal an event on the specified connection using the hypervisor event IPC.
 356  *
 357  * This involves a hypercall.
 358  */
 359 u16 hv_signal_event(void *con_id)
 360 {
 361         u16 status;
 362
 363         status = (do_hypercall(HVCALL_SIGNAL_EVENT, con_id, NULL) & 0xFFFF);
 364
 365         return status;
 366 }
 367
 368 static int hv_ce_set_next_event(unsigned long delta,
 369                                 struct clock_event_device *evt)
 370 {
 371         cycle_t current_tick;
 372
 373         WARN_ON(!clockevent_state_oneshot(evt));
 374
 375         rdmsrl(HV_X64_MSR_TIME_REF_COUNT, current_tick);
 376         current_tick += delta;
 377         wrmsrl(HV_X64_MSR_STIMER0_COUNT, current_tick);
 378         return 0;
 379 }
 380
 381 static int hv_ce_shutdown(struct clock_event_device *evt)
 382 {
 383         wrmsrl(HV_X64_MSR_STIMER0_COUNT, 0);
 384         wrmsrl(HV_X64_MSR_STIMER0_CONFIG, 0);
 385
 386         return 0;
 387 }
 388
 389 static int hv_ce_set_oneshot(struct clock_event_device *evt)
 390 {
 391         union hv_timer_config timer_cfg;
 392
 393         timer_cfg.enable = 1;
 394         timer_cfg.auto_enable = 1;
 395         timer_cfg.sintx = VMBUS_MESSAGE_SINT;
 396         wrmsrl(HV_X64_MSR_STIMER0_CONFIG, timer_cfg.as_uint64);
 397
 398         return 0;
 399 }
 400
 401 static void hv_init_clockevent_device(struct clock_event_device *dev, int cpu)
 402 {
 403         dev->name = "Hyper-V clockevent";
 404         dev->features = CLOCK_EVT_FEAT_ONESHOT;
 405         dev->cpumask = cpumask_of(cpu);
 406         dev->rating = 1000;
 407         /*
 408          * Avoid settint dev->owner = THIS_MODULE deliberately as doing so will
 409          * result in clockevents_config_and_register() taking additional
 410          * references to the hv_vmbus module making it impossible to unload.
 411          */
 412
 413         dev->set_state_shutdown = hv_ce_shutdown;
 414         dev->set_state_oneshot = hv_ce_set_oneshot;
 415         dev->set_next_event = hv_ce_set_next_event;
 416 }
 417
 418
 419 int hv_synic_alloc(void)
 420 {
 421         size_t size = sizeof(struct tasklet_struct);
 422         size_t ced_size = sizeof(struct clock_event_device);
 423         int cpu;
 424
 425         hv_context.hv_numa_map = kzalloc(sizeof(struct cpumask) * nr_node_ids,
 426                                          GFP_ATOMIC);
 427         if (hv_context.hv_numa_map == NULL) {
 428                 pr_err("Unable to allocate NUMA map\n");
 429                 goto err;
 430         }
 431
 432         for_each_present_cpu(cpu) {
 433                 hv_context.event_dpc[cpu] = kmalloc(size, GFP_ATOMIC);
 434                 if (hv_context.event_dpc[cpu] == NULL) {
 435                         pr_err("Unable to allocate event dpc\n");
 436                         goto err;
 437                 }
 438                 tasklet_init(hv_context.event_dpc[cpu], vmbus_on_event, cpu);
 439
 440                 hv_context.clk_evt[cpu] = kzalloc(ced_size, GFP_ATOMIC);
 441                 if (hv_context.clk_evt[cpu] == NULL) {
 442                         pr_err("Unable to allocate clock event device\n");
 443                         goto err;
 444                 }
 445
 446                 hv_init_clockevent_device(hv_context.clk_evt[cpu], cpu);
 447
 448                 hv_context.synic_message_page[cpu] =
 449                         (void *)get_zeroed_page(GFP_ATOMIC);
 450
 451                 if (hv_context.synic_message_page[cpu] == NULL) {
 452                         pr_err("Unable to allocate SYNIC message page\n");
 453                         goto err;
 454                 }
 455
 456                 hv_context.synic_event_page[cpu] =
 457                         (void *)get_zeroed_page(GFP_ATOMIC);
 458
 459                 if (hv_context.synic_event_page[cpu] == NULL) {
 460                         pr_err("Unable to allocate SYNIC event page\n");
 461                         goto err;
 462                 }
 463
 464                 hv_context.post_msg_page[cpu] =
 465                         (void *)get_zeroed_page(GFP_ATOMIC);
 466
 467                 if (hv_context.post_msg_page[cpu] == NULL) {
 468                         pr_err("Unable to allocate post msg page\n");
 469                         goto err;
 470                 }
 471
 472                 INIT_LIST_HEAD(&hv_context.percpu_list[cpu]);
 473         }
 474
 475         return 0;
 476 err:
 477         return -ENOMEM;
 478 }
 479
 480 static void hv_synic_free_cpu(int cpu)
 481 {
 482         kfree(hv_context.event_dpc[cpu]);
 483         kfree(hv_context.clk_evt[cpu]);
 484         if (hv_context.synic_event_page[cpu])
 485                 free_page((unsigned long)hv_context.synic_event_page[cpu]);
 486         if (hv_context.synic_message_page[cpu])
 487                 free_page((unsigned long)hv_context.synic_message_page[cpu]);
 488         if (hv_context.post_msg_page[cpu])
 489                 free_page((unsigned long)hv_context.post_msg_page[cpu]);
 490 }
 491
 492 void hv_synic_free(void)
 493 {
 494         int cpu;
 495
 496         kfree(hv_context.hv_numa_map);
 497         for_each_present_cpu(cpu)
 498                 hv_synic_free_cpu(cpu);
 499 }
 500
 501 /*
 502  * hv_synic_init - Initialize the Synthethic Interrupt Controller.
 503  *
 504  * If it is already initialized by another entity (ie x2v shim), we need to
 505  * retrieve the initialized message and event pages.  Otherwise, we create and
 506  * initialize the message and event pages.
 507  */
 508 void hv_synic_init(void *arg)
 509 {
 510         u64 version;
 511         union hv_synic_simp simp;
 512         union hv_synic_siefp siefp;
 513         union hv_synic_sint shared_sint;
 514         union hv_synic_scontrol sctrl;
 515         u64 vp_index;
 516
 517         int cpu = smp_processor_id();
 518
 519         if (!hv_context.hypercall_page)
 520                 return;
 521
 522         /* Check the version */
 523         rdmsrl(HV_X64_MSR_SVERSION, version);
 524
 525         /* Setup the Synic's message page */
 526         rdmsrl(HV_X64_MSR_SIMP, simp.as_uint64);
 527         simp.simp_enabled = 1;
 528         simp.base_simp_gpa = virt_to_phys(hv_context.synic_message_page[cpu])
 529                 >> PAGE_SHIFT;
 530
 531         wrmsrl(HV_X64_MSR_SIMP, simp.as_uint64);
 532
 533         /* Setup the Synic's event page */
 534         rdmsrl(HV_X64_MSR_SIEFP, siefp.as_uint64);
 535         siefp.siefp_enabled = 1;
 536         siefp.base_siefp_gpa = virt_to_phys(hv_context.synic_event_page[cpu])
 537                 >> PAGE_SHIFT;
 538
 539         wrmsrl(HV_X64_MSR_SIEFP, siefp.as_uint64);
 540
 541         /* Setup the shared SINT. */
 542         rdmsrl(HV_X64_MSR_SINT0 + VMBUS_MESSAGE_SINT, shared_sint.as_uint64);
 543
 544         shared_sint.as_uint64 = 0;
 545         shared_sint.vector = HYPERVISOR_CALLBACK_VECTOR;
 546         shared_sint.masked = false;
 547         shared_sint.auto_eoi = true;
 548
 549         wrmsrl(HV_X64_MSR_SINT0 + VMBUS_MESSAGE_SINT, shared_sint.as_uint64);
 550
 551         /* Enable the global synic bit */
 552         rdmsrl(HV_X64_MSR_SCONTROL, sctrl.as_uint64);
 553         sctrl.enable = 1;
 554
 555         wrmsrl(HV_X64_MSR_SCONTROL, sctrl.as_uint64);
 556
 557         hv_context.synic_initialized = true;
 558
 559         /*
 560          * Setup the mapping between Hyper-V's notion
 561          * of cpuid and Linux' notion of cpuid.
 562          * This array will be indexed using Linux cpuid.
 563          */
 564         rdmsrl(HV_X64_MSR_VP_INDEX, vp_index);
 565         hv_context.vp_index[cpu] = (u32)vp_index;
 566
 567         /*
 568          * Register the per-cpu clockevent source.
 569          */
 570         if (ms_hyperv.features & HV_X64_MSR_SYNTIMER_AVAILABLE)
 571                 clockevents_config_and_register(hv_context.clk_evt[cpu],
 572                                                 HV_TIMER_FREQUENCY,
 573                                                 HV_MIN_DELTA_TICKS,
 574                                                 HV_MAX_MAX_DELTA_TICKS);
 575         return;
 576 }
 577
 578 /*
 579  * hv_synic_clockevents_cleanup - Cleanup clockevent devices
 580  */
 581 void hv_synic_clockevents_cleanup(void)
 582 {
 583         int cpu;
 584
 585         if (!(ms_hyperv.features & HV_X64_MSR_SYNTIMER_AVAILABLE))
 586                 return;
 587
 588         for_each_online_cpu(cpu)
 589                 clockevents_unbind_device(hv_context.clk_evt[cpu], cpu);
 590 }
 591
 592 /*
 593  * hv_synic_cleanup - Cleanup routine for hv_synic_init().
 594  */
 595 void hv_synic_cleanup(void *arg)
 596 {
 597         union hv_synic_sint shared_sint;
 598         union hv_synic_simp simp;
 599         union hv_synic_siefp siefp;
 600         union hv_synic_scontrol sctrl;
 601         int cpu = smp_processor_id();
 602
 603         if (!hv_context.synic_initialized)
 604                 return;
 605
 606         /* Turn off clockevent device */
 607         if (ms_hyperv.features & HV_X64_MSR_SYNTIMER_AVAILABLE)
 608                 hv_ce_shutdown(hv_context.clk_evt[cpu]);
 609
 610         rdmsrl(HV_X64_MSR_SINT0 + VMBUS_MESSAGE_SINT, shared_sint.as_uint64);
 611
 612         shared_sint.masked = 1;
 613
 614         /* Need to correctly cleanup in the case of SMP!!! */
 615         /* Disable the interrupt */
 616         wrmsrl(HV_X64_MSR_SINT0 + VMBUS_MESSAGE_SINT, shared_sint.as_uint64);
 617
 618         rdmsrl(HV_X64_MSR_SIMP, simp.as_uint64);
 619         simp.simp_enabled = 0;
 620         simp.base_simp_gpa = 0;
 621
 622         wrmsrl(HV_X64_MSR_SIMP, simp.as_uint64);
 623
 624         rdmsrl(HV_X64_MSR_SIEFP, siefp.as_uint64);
 625         siefp.siefp_enabled = 0;
 626         siefp.base_siefp_gpa = 0;
 627
 628         wrmsrl(HV_X64_MSR_SIEFP, siefp.as_uint64);
 629
 630         /* Disable the global synic bit */
 631         rdmsrl(HV_X64_MSR_SCONTROL, sctrl.as_uint64);
 632         sctrl.enable = 0;
 633         wrmsrl(HV_X64_MSR_SCONTROL, sctrl.as_uint64);
 634 }