Date: Mon, 30 May 2016 08:25:09 +0000 (UTC) From: Sepherosa Ziehau <sephe@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r300987 - head/sys/dev/hyperv/vmbus Message-ID: <201605300825.u4U8P9Qx082125@repo.freebsd.org>
next in thread | raw e-mail | index | archive | help
Author: sephe Date: Mon May 30 08:25:09 2016 New Revision: 300987 URL: https://svnweb.freebsd.org/changeset/base/300987 Log: hyperv/et: Fix STIMER0 operations. - Make sure that STIMER0 is disabled before writting to it, since writing to an enabled STIMER will result in undefined behaviour. - It is unnecessary to reconfigure STIMER0 upon each et_start(). - Make sure that MSR_HV_REF_TIME_COUNT will not return 0, since writing 0 to STIMER_COUNT will disable the target STIMER. MFC after: 1 week Sponsored by: Microsoft OSTC Differential Revision: https://reviews.freebsd.org/D6573 Modified: head/sys/dev/hyperv/vmbus/hv_et.c Modified: head/sys/dev/hyperv/vmbus/hv_et.c ============================================================================== --- head/sys/dev/hyperv/vmbus/hv_et.c Mon May 30 07:50:57 2016 (r300986) +++ head/sys/dev/hyperv/vmbus/hv_et.c Mon May 30 08:25:09 2016 (r300987) @@ -61,40 +61,27 @@ __FBSDID("$FreeBSD$"); static struct eventtimer *et; -static inline uint64_t +static __inline uint64_t sbintime2tick(sbintime_t time) { struct timespec val; val = sbttots(time); - return val.tv_sec * HV_TIMER_FREQUENCY + val.tv_nsec / 100; + return (val.tv_sec * HV_TIMER_FREQUENCY) + (val.tv_nsec / 100); } static int hv_et_start(struct eventtimer *et, sbintime_t firsttime, sbintime_t periodtime) { - uint64_t current, config; - - config = MSR_HV_STIMER_CFG_AUTOEN | MSR_HV_STIMER0_CFG_SINT; + uint64_t current; current = rdmsr(MSR_HV_TIME_REF_COUNT); current += sbintime2tick(firsttime); - - wrmsr(MSR_HV_STIMER0_CONFIG, config); wrmsr(MSR_HV_STIMER0_COUNT, current); return (0); } -static int -hv_et_stop(struct eventtimer *et) -{ - wrmsr(MSR_HV_STIMER0_CONFIG, 0); - wrmsr(MSR_HV_STIMER0_COUNT, 0); - - return (0); -} - void hv_et_intr(struct trapframe *frame) { @@ -130,6 +117,31 @@ hv_et_probe(device_t dev) return (BUS_PROBE_NOWILDCARD); } +static void +vmbus_et_config(void *arg __unused) +{ + /* + * Make sure that STIMER0 is really disabled before writing + * to STIMER0_CONFIG. + * + * "Writing to the configuration register of a timer that + * is already enabled may result in undefined behaviour." + */ + for (;;) { + uint64_t val; + + /* Stop counting, and this also implies disabling STIMER0 */ + wrmsr(MSR_HV_STIMER0_COUNT, 0); + + val = rdmsr(MSR_HV_STIMER0_CONFIG); + if ((val & MSR_HV_STIMER_CFG_ENABLE) == 0) + break; + cpu_spinwait(); + } + wrmsr(MSR_HV_STIMER0_CONFIG, + MSR_HV_STIMER_CFG_AUTOEN | MSR_HV_STIMER0_CFG_SINT); +} + static int hv_et_attach(device_t dev) { @@ -143,9 +155,16 @@ hv_et_attach(device_t dev) et->et_min_period = HV_MIN_DELTA_TICKS * ((1LL << 32) / HV_TIMER_FREQUENCY); et->et_max_period = HV_MAX_DELTA_TICKS * ((1LL << 32) / HV_TIMER_FREQUENCY); et->et_start = hv_et_start; - et->et_stop = hv_et_stop; et->et_priv = dev; + /* + * Delay a bit to make sure that MSR_HV_TIME_REF_COUNT will + * not return 0, since writing 0 to STIMER0_COUNT will disable + * STIMER0. + */ + DELAY(100); + smp_rendezvous(NULL, vmbus_et_config, NULL, NULL); + return (et_register(et)); }
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?201605300825.u4U8P9Qx082125>