The Design and Implementation of the FreeBSD Operating System, Second Edition
Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)


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FreeBSD/Linux Kernel Cross Reference
sys/dev/hyperv/vmbus/vmbus_et.c

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    1 /*-
    2  * Copyright (c) 2015,2016-2017 Microsoft Corp.
    3  * All rights reserved.
    4  *
    5  * Redistribution and use in source and binary forms, with or without
    6  * modification, are permitted provided that the following conditions
    7  * are met:
    8  * 1. Redistributions of source code must retain the above copyright
    9  *      notice, this list of conditions and the following disclaimer.
   10  * 2. Redistributions in binary form must reproduce the above copyright
   11  *      notice, this list of conditions and the following disclaimer in the
   12  *      documentation and/or other materials provided with the distribution.
   13  *
   14  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
   15  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   16  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   17  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
   18  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   19  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   20  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   21  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   22  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   23  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   24  * SUCH DAMAGE.
   25  */
   26 
   27 #include <sys/cdefs.h>
   28 __FBSDID("$FreeBSD$");
   29 
   30 #include <sys/param.h>
   31 #include <sys/bus.h>
   32 #include <sys/kernel.h>
   33 #include <sys/module.h>
   34 #include <sys/proc.h>
   35 #include <sys/smp.h>
   36 #include <sys/systm.h>
   37 #include <sys/timeet.h>
   38 
   39 #include <dev/hyperv/include/hyperv.h>
   40 #if defined(__aarch64__)
   41 #include <dev/hyperv/vmbus/aarch64/hyperv_reg.h>
   42 #else
   43 #include <dev/hyperv/vmbus/x86/hyperv_reg.h>
   44 #endif
   45 #include <dev/hyperv/vmbus/hyperv_var.h>
   46 #include <dev/hyperv/vmbus/vmbus_var.h>
   47 #include <dev/hyperv/vmbus/hyperv_common_reg.h>
   48 
   49 #define VMBUS_ET_NAME                   "hvet"
   50 
   51 #define MSR_HV_STIMER0_CFG_SINT         \
   52         ((((uint64_t)VMBUS_SINT_TIMER) << MSR_HV_STIMER_CFG_SINT_SHIFT) & \
   53          MSR_HV_STIMER_CFG_SINT_MASK)
   54 
   55 /*
   56  * Additionally required feature:
   57  * - SynIC is needed for interrupt generation.
   58  */
   59 #define CPUID_HV_ET_MASK                (CPUID_HV_MSR_SYNIC |           \
   60                                          CPUID_HV_MSR_SYNTIMER)
   61 
   62 static void                     vmbus_et_identify(driver_t *, device_t);
   63 static int                      vmbus_et_probe(device_t);
   64 static int                      vmbus_et_attach(device_t);
   65 static int                      vmbus_et_detach(device_t);
   66 static int                      vmbus_et_start(struct eventtimer *, sbintime_t,
   67                                     sbintime_t);
   68 
   69 static struct eventtimer        vmbus_et;
   70 
   71 static device_method_t vmbus_et_methods[] = {
   72         DEVMETHOD(device_identify,      vmbus_et_identify),
   73         DEVMETHOD(device_probe,         vmbus_et_probe),
   74         DEVMETHOD(device_attach,        vmbus_et_attach),
   75         DEVMETHOD(device_detach,        vmbus_et_detach),
   76 
   77         DEVMETHOD_END
   78 };
   79 
   80 static driver_t vmbus_et_driver = {
   81         VMBUS_ET_NAME,
   82         vmbus_et_methods,
   83         0
   84 };
   85 
   86 DRIVER_MODULE(hv_et, vmbus, vmbus_et_driver, NULL, NULL);
   87 MODULE_VERSION(hv_et, 1);
   88 
   89 static __inline uint64_t
   90 hyperv_sbintime2count(sbintime_t time)
   91 {
   92         struct timespec val;
   93 
   94         val = sbttots(time);
   95         return (val.tv_sec * HYPERV_TIMER_FREQ) +
   96             (val.tv_nsec / HYPERV_TIMER_NS_FACTOR);
   97 }
   98 
   99 static int
  100 vmbus_et_start(struct eventtimer *et __unused, sbintime_t first,
  101     sbintime_t period __unused)
  102 {
  103         uint64_t current;
  104 
  105         current = hyperv_tc64();
  106         current += hyperv_sbintime2count(first);
  107         wrmsr(MSR_HV_STIMER0_COUNT, current);
  108 
  109         return (0);
  110 }
  111 
  112 void
  113 vmbus_et_intr(struct trapframe *frame)
  114 {
  115         struct trapframe *oldframe;
  116         struct thread *td;
  117 
  118         if (vmbus_et.et_active) {
  119                 td = curthread;
  120                 td->td_intr_nesting_level++;
  121                 oldframe = td->td_intr_frame;
  122                 td->td_intr_frame = frame;
  123                 vmbus_et.et_event_cb(&vmbus_et, vmbus_et.et_arg);
  124                 td->td_intr_frame = oldframe;
  125                 td->td_intr_nesting_level--;
  126         }
  127 }
  128 
  129 static void
  130 vmbus_et_identify(driver_t *driver, device_t parent)
  131 {
  132         if (device_get_unit(parent) != 0 ||
  133             device_find_child(parent, VMBUS_ET_NAME, -1) != NULL ||
  134             (hyperv_features & CPUID_HV_ET_MASK) != CPUID_HV_ET_MASK ||
  135             hyperv_tc64 == NULL)
  136                 return;
  137 
  138         device_add_child(parent, VMBUS_ET_NAME, -1);
  139 }
  140 
  141 static int
  142 vmbus_et_probe(device_t dev)
  143 {
  144         if (resource_disabled(VMBUS_ET_NAME, 0))
  145                 return (ENXIO);
  146 
  147         device_set_desc(dev, "Hyper-V event timer");
  148 
  149         return (BUS_PROBE_NOWILDCARD);
  150 }
  151 
  152 static void
  153 vmbus_et_config(void *arg __unused)
  154 {
  155         /*
  156          * Make sure that STIMER0 is really disabled before writing
  157          * to STIMER0_CONFIG.
  158          *
  159          * "Writing to the configuration register of a timer that
  160          *  is already enabled may result in undefined behaviour."
  161          */
  162         for (;;) {
  163                 uint64_t val;
  164 
  165                 /* Stop counting, and this also implies disabling STIMER0 */
  166                 wrmsr(MSR_HV_STIMER0_COUNT, 0);
  167 
  168                 val = rdmsr(MSR_HV_STIMER0_CONFIG);
  169                 if ((val & MSR_HV_STIMER_CFG_ENABLE) == 0)
  170                         break;
  171                 cpu_spinwait();
  172         }
  173         wrmsr(MSR_HV_STIMER0_CONFIG,
  174             MSR_HV_STIMER_CFG_AUTOEN | MSR_HV_STIMER0_CFG_SINT);
  175 }
  176 
  177 static int
  178 vmbus_et_attach(device_t dev)
  179 {
  180         /* TODO: use independent IDT vector */
  181 
  182         vmbus_et.et_name = "Hyper-V";
  183         vmbus_et.et_flags = ET_FLAGS_ONESHOT | ET_FLAGS_PERCPU;
  184         vmbus_et.et_quality = 1000;
  185         vmbus_et.et_frequency = HYPERV_TIMER_FREQ;
  186         vmbus_et.et_min_period = (0x00000001ULL << 32) / HYPERV_TIMER_FREQ;
  187         vmbus_et.et_max_period = (0xfffffffeULL << 32) / HYPERV_TIMER_FREQ;
  188         vmbus_et.et_start = vmbus_et_start;
  189 
  190         /*
  191          * Delay a bit to make sure that hyperv_tc64 will not return 0,
  192          * since writing 0 to STIMER0_COUNT will disable STIMER0.
  193          */
  194         DELAY(100);
  195         smp_rendezvous(NULL, vmbus_et_config, NULL, NULL);
  196 
  197         return (et_register(&vmbus_et));
  198 }
  199 
  200 static int
  201 vmbus_et_detach(device_t dev)
  202 {
  203         return (et_deregister(&vmbus_et));
  204 }

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