25ce9181cf
KVM clock shares the same data structures between the guest and the host as Xen so it makes sense to just have a single copy of this code. Differential Revision: https://reviews.freebsd.org/D1429 Reviewed by: royger (eariler version) MFC after: 1 month
536 lines
14 KiB
C
536 lines
14 KiB
C
/*-
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* Copyright (c) 2009 Adrian Chadd
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* Copyright (c) 2012 Spectra Logic Corporation
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*
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*/
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/**
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* \file dev/xen/timer/timer.c
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* \brief A timer driver for the Xen hypervisor's PV clock.
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*/
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#include <sys/cdefs.h>
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__FBSDID("$FreeBSD$");
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#include <sys/param.h>
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#include <sys/systm.h>
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#include <sys/bus.h>
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#include <sys/kernel.h>
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#include <sys/module.h>
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#include <sys/time.h>
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#include <sys/timetc.h>
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#include <sys/timeet.h>
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#include <sys/smp.h>
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#include <sys/limits.h>
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#include <sys/clock.h>
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#include <sys/proc.h>
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#include <xen/xen-os.h>
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#include <xen/features.h>
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#include <xen/xen_intr.h>
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#include <xen/hypervisor.h>
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#include <xen/interface/io/xenbus.h>
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#include <xen/interface/vcpu.h>
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#include <machine/cpu.h>
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#include <machine/cpufunc.h>
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#include <machine/clock.h>
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#include <machine/_inttypes.h>
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#include <machine/smp.h>
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#include <machine/pvclock.h>
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#include <dev/xen/timer/timer.h>
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#include "clock_if.h"
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static devclass_t xentimer_devclass;
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#define NSEC_IN_SEC 1000000000ULL
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#define NSEC_IN_USEC 1000ULL
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/* 18446744073 = int(2^64 / NSEC_IN_SC) = 1 ns in 64-bit fractions */
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#define FRAC_IN_NSEC 18446744073LL
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/* Xen timers may fire up to 100us off */
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#define XENTIMER_MIN_PERIOD_IN_NSEC 100*NSEC_IN_USEC
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#define XENCLOCK_RESOLUTION 10000000
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#define ETIME 62 /* Xen "bad time" error */
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#define XENTIMER_QUALITY 950
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struct xentimer_pcpu_data {
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uint64_t timer;
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uint64_t last_processed;
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void *irq_handle;
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};
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DPCPU_DEFINE(struct xentimer_pcpu_data, xentimer_pcpu);
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DPCPU_DECLARE(struct vcpu_info *, vcpu_info);
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struct xentimer_softc {
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device_t dev;
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struct timecounter tc;
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struct eventtimer et;
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};
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static void
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xentimer_identify(driver_t *driver, device_t parent)
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{
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if (!xen_domain())
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return;
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/* Handle all Xen PV timers in one device instance. */
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if (devclass_get_device(xentimer_devclass, 0))
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return;
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BUS_ADD_CHILD(parent, 0, "xen_et", 0);
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}
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static int
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xentimer_probe(device_t dev)
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{
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KASSERT((xen_domain()), ("Trying to use Xen timer on bare metal"));
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/*
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* In order to attach, this driver requires the following:
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* - Vector callback support by the hypervisor, in order to deliver
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* timer interrupts to the correct CPU for CPUs other than 0.
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* - Access to the hypervisor shared info page, in order to look up
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* each VCPU's timer information and the Xen wallclock time.
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* - The hypervisor must say its PV clock is "safe" to use.
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* - The hypervisor must support VCPUOP hypercalls.
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* - The maximum number of CPUs supported by FreeBSD must not exceed
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* the number of VCPUs supported by the hypervisor.
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*/
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#define XTREQUIRES(condition, reason...) \
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if (!(condition)) { \
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device_printf(dev, ## reason); \
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device_detach(dev); \
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return (ENXIO); \
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}
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if (xen_hvm_domain()) {
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XTREQUIRES(xen_vector_callback_enabled,
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"vector callbacks unavailable\n");
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XTREQUIRES(xen_feature(XENFEAT_hvm_safe_pvclock),
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"HVM safe pvclock unavailable\n");
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}
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XTREQUIRES(HYPERVISOR_shared_info != NULL,
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"shared info page unavailable\n");
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XTREQUIRES(HYPERVISOR_vcpu_op(VCPUOP_stop_periodic_timer, 0, NULL) == 0,
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"VCPUOPs interface unavailable\n");
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#undef XTREQUIRES
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device_set_desc(dev, "Xen PV Clock");
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return (BUS_PROBE_NOWILDCARD);
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}
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/**
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* \brief Get the current time, in nanoseconds, since the hypervisor booted.
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*
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* \param vcpu vcpu_info structure to fetch the time from.
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*
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*/
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static uint64_t
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xen_fetch_vcpu_time(struct vcpu_info *vcpu)
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{
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struct pvclock_vcpu_time_info *time;
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time = (struct pvclock_vcpu_time_info *) &vcpu->time;
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return (pvclock_get_timecount(time));
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}
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static uint32_t
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xentimer_get_timecount(struct timecounter *tc)
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{
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uint64_t vcpu_time;
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/*
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* We don't disable preemption here because the worst that can
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* happen is reading the vcpu_info area of a different CPU than
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* the one we are currently running on, but that would also
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* return a valid tc (and we avoid the overhead of
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* critical_{enter/exit} calls).
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*/
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vcpu_time = xen_fetch_vcpu_time(DPCPU_GET(vcpu_info));
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return (vcpu_time & UINT32_MAX);
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}
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/**
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* \brief Fetch the hypervisor boot time, known as the "Xen wallclock".
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*
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* \param ts Timespec to store the current stable value.
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* \param version Pointer to store the corresponding wallclock version.
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*
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* \note This value is updated when Domain-0 shifts its clock to follow
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* clock drift, e.g. as detected by NTP.
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*/
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static void
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xen_fetch_wallclock(struct timespec *ts)
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{
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shared_info_t *src = HYPERVISOR_shared_info;
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struct pvclock_wall_clock *wc;
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wc = (struct pvclock_wall_clock *) &src->wc_version;
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pvclock_get_wallclock(wc, ts);
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}
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static void
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xen_fetch_uptime(struct timespec *ts)
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{
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uint64_t uptime;
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uptime = xen_fetch_vcpu_time(DPCPU_GET(vcpu_info));
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ts->tv_sec = uptime / NSEC_IN_SEC;
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ts->tv_nsec = uptime % NSEC_IN_SEC;
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}
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static int
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xentimer_settime(device_t dev __unused, struct timespec *ts)
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{
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/*
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* Don't return EINVAL here; just silently fail if the domain isn't
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* privileged enough to set the TOD.
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*/
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return (0);
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}
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/**
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* \brief Return current time according to the Xen Hypervisor wallclock.
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*
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* \param dev Xentimer device.
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* \param ts Pointer to store the wallclock time.
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*
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* \note The Xen time structures document the hypervisor start time and the
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* uptime-since-hypervisor-start (in nsec.) They need to be combined
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* in order to calculate a TOD clock.
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*/
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static int
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xentimer_gettime(device_t dev, struct timespec *ts)
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{
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struct timespec u_ts;
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timespecclear(ts);
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xen_fetch_wallclock(ts);
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xen_fetch_uptime(&u_ts);
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timespecadd(ts, &u_ts);
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return (0);
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}
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/**
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* \brief Handle a timer interrupt for the Xen PV timer driver.
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*
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* \param arg Xen timer driver softc that is expecting the interrupt.
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*/
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static int
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xentimer_intr(void *arg)
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{
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struct xentimer_softc *sc = (struct xentimer_softc *)arg;
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struct xentimer_pcpu_data *pcpu = DPCPU_PTR(xentimer_pcpu);
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pcpu->last_processed = xen_fetch_vcpu_time(DPCPU_GET(vcpu_info));
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if (pcpu->timer != 0 && sc->et.et_active)
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sc->et.et_event_cb(&sc->et, sc->et.et_arg);
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return (FILTER_HANDLED);
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}
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static int
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xentimer_vcpu_start_timer(int vcpu, uint64_t next_time)
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{
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struct vcpu_set_singleshot_timer single;
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single.timeout_abs_ns = next_time;
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single.flags = VCPU_SSHOTTMR_future;
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return (HYPERVISOR_vcpu_op(VCPUOP_set_singleshot_timer, vcpu, &single));
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}
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static int
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xentimer_vcpu_stop_timer(int vcpu)
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{
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return (HYPERVISOR_vcpu_op(VCPUOP_stop_singleshot_timer, vcpu, NULL));
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}
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/**
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* \brief Set the next oneshot time for the current CPU.
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*
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* \param et Xen timer driver event timer to schedule on.
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* \param first Delta to the next time to schedule the interrupt for.
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* \param period Not used.
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*
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* \note See eventtimers(9) for more information.
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* \note
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*
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* \returns 0
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*/
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static int
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xentimer_et_start(struct eventtimer *et,
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sbintime_t first, sbintime_t period)
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{
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int error = 0, i = 0;
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struct xentimer_softc *sc = et->et_priv;
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int cpu = PCPU_GET(vcpu_id);
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struct xentimer_pcpu_data *pcpu = DPCPU_PTR(xentimer_pcpu);
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struct vcpu_info *vcpu = DPCPU_GET(vcpu_info);
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uint64_t first_in_ns, next_time;
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#ifdef INVARIANTS
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struct thread *td = curthread;
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#endif
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KASSERT(td->td_critnest != 0,
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("xentimer_et_start called without preemption disabled"));
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/* See sbttots() for this formula. */
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first_in_ns = (((first >> 32) * NSEC_IN_SEC) +
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(((uint64_t)NSEC_IN_SEC * (uint32_t)first) >> 32));
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/*
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* Retry any timer scheduling failures, where the hypervisor
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* returns -ETIME. Sometimes even a 100us timer period isn't large
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* enough, but larger period instances are relatively uncommon.
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*
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* XXX Remove the panics once et_start() and its consumers are
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* equipped to deal with start failures.
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*/
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do {
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if (++i == 60)
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panic("can't schedule timer");
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next_time = xen_fetch_vcpu_time(vcpu) + first_in_ns;
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error = xentimer_vcpu_start_timer(cpu, next_time);
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} while (error == -ETIME);
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if (error)
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panic("%s: Error %d setting singleshot timer to %"PRIu64"\n",
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device_get_nameunit(sc->dev), error, next_time);
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pcpu->timer = next_time;
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return (error);
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}
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/**
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* \brief Cancel the event timer's currently running timer, if any.
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*/
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static int
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xentimer_et_stop(struct eventtimer *et)
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{
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int cpu = PCPU_GET(vcpu_id);
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struct xentimer_pcpu_data *pcpu = DPCPU_PTR(xentimer_pcpu);
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pcpu->timer = 0;
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return (xentimer_vcpu_stop_timer(cpu));
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}
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/**
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* \brief Attach a Xen PV timer driver instance.
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*
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* \param dev Bus device object to attach.
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*
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* \note
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* \returns EINVAL
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*/
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static int
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xentimer_attach(device_t dev)
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{
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struct xentimer_softc *sc = device_get_softc(dev);
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int error, i;
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sc->dev = dev;
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/* Bind an event channel to a VIRQ on each VCPU. */
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CPU_FOREACH(i) {
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struct xentimer_pcpu_data *pcpu;
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pcpu = DPCPU_ID_PTR(i, xentimer_pcpu);
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error = HYPERVISOR_vcpu_op(VCPUOP_stop_periodic_timer, i, NULL);
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if (error) {
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device_printf(dev, "Error disabling Xen periodic timer "
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"on CPU %d\n", i);
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return (error);
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}
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error = xen_intr_bind_virq(dev, VIRQ_TIMER, i, xentimer_intr,
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NULL, sc, INTR_TYPE_CLK, &pcpu->irq_handle);
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if (error) {
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device_printf(dev, "Error %d binding VIRQ_TIMER "
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"to VCPU %d\n", error, i);
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return (error);
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}
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xen_intr_describe(pcpu->irq_handle, "c%d", i);
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}
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/* Register the event timer. */
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sc->et.et_name = "XENTIMER";
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sc->et.et_quality = XENTIMER_QUALITY;
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sc->et.et_flags = ET_FLAGS_ONESHOT | ET_FLAGS_PERCPU;
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sc->et.et_frequency = NSEC_IN_SEC;
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/* See tstosbt() for this formula */
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sc->et.et_min_period = (XENTIMER_MIN_PERIOD_IN_NSEC *
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(((uint64_t)1 << 63) / 500000000) >> 32);
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sc->et.et_max_period = ((sbintime_t)4 << 32);
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sc->et.et_start = xentimer_et_start;
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sc->et.et_stop = xentimer_et_stop;
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sc->et.et_priv = sc;
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et_register(&sc->et);
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/* Register the timecounter. */
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sc->tc.tc_name = "XENTIMER";
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sc->tc.tc_quality = XENTIMER_QUALITY;
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sc->tc.tc_flags = TC_FLAGS_SUSPEND_SAFE;
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/*
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* The underlying resolution is in nanoseconds, since the timer info
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* scales TSC frequencies using a fraction that represents time in
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* terms of nanoseconds.
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*/
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sc->tc.tc_frequency = NSEC_IN_SEC;
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sc->tc.tc_counter_mask = ~0u;
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sc->tc.tc_get_timecount = xentimer_get_timecount;
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sc->tc.tc_priv = sc;
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tc_init(&sc->tc);
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/* Register the Hypervisor wall clock */
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clock_register(dev, XENCLOCK_RESOLUTION);
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return (0);
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}
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static int
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xentimer_detach(device_t dev)
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{
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/* Implement Xen PV clock teardown - XXX see hpet_detach ? */
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/* If possible:
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* 1. need to deregister timecounter
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* 2. need to deregister event timer
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* 3. need to deregister virtual IRQ event channels
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*/
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return (EBUSY);
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}
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static void
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xentimer_percpu_resume(void *arg)
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{
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device_t dev = (device_t) arg;
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struct xentimer_softc *sc = device_get_softc(dev);
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xentimer_et_start(&sc->et, sc->et.et_min_period, 0);
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}
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static int
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xentimer_resume(device_t dev)
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{
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int error;
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int i;
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/* Disable the periodic timer */
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CPU_FOREACH(i) {
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error = HYPERVISOR_vcpu_op(VCPUOP_stop_periodic_timer, i, NULL);
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if (error != 0) {
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device_printf(dev,
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"Error disabling Xen periodic timer on CPU %d\n",
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i);
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return (error);
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}
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}
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/* Reset the last uptime value */
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pvclock_resume();
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/* Reset the RTC clock */
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inittodr(time_second);
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/* Kick the timers on all CPUs */
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smp_rendezvous(NULL, xentimer_percpu_resume, NULL, dev);
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if (bootverbose)
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device_printf(dev, "resumed operation after suspension\n");
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return (0);
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}
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static int
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xentimer_suspend(device_t dev)
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{
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return (0);
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}
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/*
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* Xen early clock init
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*/
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void
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xen_clock_init(void)
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{
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}
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/*
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* Xen PV DELAY function
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*
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* When running on PVH mode we don't have an emulated i8524, so
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* make use of the Xen time info in order to code a simple DELAY
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* function that can be used during early boot.
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*/
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void
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xen_delay(int n)
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{
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struct vcpu_info *vcpu = &HYPERVISOR_shared_info->vcpu_info[0];
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uint64_t end_ns;
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uint64_t current;
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end_ns = xen_fetch_vcpu_time(vcpu);
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end_ns += n * NSEC_IN_USEC;
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for (;;) {
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current = xen_fetch_vcpu_time(vcpu);
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if (current >= end_ns)
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break;
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}
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}
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static device_method_t xentimer_methods[] = {
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DEVMETHOD(device_identify, xentimer_identify),
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|
DEVMETHOD(device_probe, xentimer_probe),
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|
DEVMETHOD(device_attach, xentimer_attach),
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|
DEVMETHOD(device_detach, xentimer_detach),
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|
DEVMETHOD(device_suspend, xentimer_suspend),
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|
DEVMETHOD(device_resume, xentimer_resume),
|
|
/* clock interface */
|
|
DEVMETHOD(clock_gettime, xentimer_gettime),
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|
DEVMETHOD(clock_settime, xentimer_settime),
|
|
DEVMETHOD_END
|
|
};
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|
|
|
static driver_t xentimer_driver = {
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|
"xen_et",
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|
xentimer_methods,
|
|
sizeof(struct xentimer_softc),
|
|
};
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|
|
|
DRIVER_MODULE(xentimer, xenpv, xentimer_driver, xentimer_devclass, 0, 0);
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|
MODULE_DEPEND(xentimer, xenpv, 1, 1, 1);
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