Date: Sun, 29 Jan 2023 18:55:51 GMT From: Mark Johnston <markj@FreeBSD.org> To: src-committers@FreeBSD.org, dev-commits-src-all@FreeBSD.org, dev-commits-src-branches@FreeBSD.org Subject: git: 8497b431f19e - stable/13 - kvmclock: Fix initialization when EARLY_AP_STARTUP is not defined Message-ID: <202301291855.30TItpNP092695@gitrepo.freebsd.org>
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The branch stable/13 has been updated by markj: URL: https://cgit.FreeBSD.org/src/commit/?id=8497b431f19efac28a1f1f64f78037f37d7c671e commit 8497b431f19efac28a1f1f64f78037f37d7c671e Author: Mark Johnston <markj@FreeBSD.org> AuthorDate: 2023-01-13 15:01:00 +0000 Commit: Mark Johnston <markj@FreeBSD.org> CommitDate: 2023-01-29 18:55:42 +0000 kvmclock: Fix initialization when EARLY_AP_STARTUP is not defined To attach to the hypervisor, kvmclock needs to write a per-CPU MSR. When EARLY_AP_STARTUP is not defined, device attach happens too early: APs are not yet spun up, so smp_rendezvous only runs the callback on the local CPU. As a result, the timecounter only gets initialized on the BSP, and then timekeeping is broken on SMP systems. Implement handling for !EARLY_AP_STARTUP kernels: keep track of the CPU on which device attach ran, and then use a SI_SUB_SMP SYSINIT to register the rest of the CPUs with the hypervisor. Reported by: Shrikanth R Kamath <kshrikanth@juniper.net> Reviewed by: kib, jhb (earlier versions) Sponsored by: Klara, Inc. Sponsored by: Juniper Networks, Inc. MFC after: 2 weeks Differential Revision: https://reviews.freebsd.org/D37705 (cherry picked from commit 568f552b0410f4f72db9ce710f7803acca23f79f) --- sys/dev/kvm_clock/kvm_clock.c | 46 ++++++++++++++++++++++++++++++++++++++----- 1 file changed, 41 insertions(+), 5 deletions(-) diff --git a/sys/dev/kvm_clock/kvm_clock.c b/sys/dev/kvm_clock/kvm_clock.c index 1a76432e417d..982a345a74c7 100644 --- a/sys/dev/kvm_clock/kvm_clock.c +++ b/sys/dev/kvm_clock/kvm_clock.c @@ -70,12 +70,16 @@ struct kvm_clock_softc { struct pvclock_vcpu_time_info *timeinfos; u_int msr_tc; u_int msr_wc; +#ifndef EARLY_AP_STARTUP + int firstcpu; +#endif }; static devclass_t kvm_clock_devclass; static struct pvclock_wall_clock *kvm_clock_get_wallclock(void *arg); -static void kvm_clock_system_time_enable(struct kvm_clock_softc *sc); +static void kvm_clock_system_time_enable(struct kvm_clock_softc *sc, + const cpuset_t *cpus); static void kvm_clock_system_time_enable_pcpu(void *arg); static struct pvclock_wall_clock * @@ -88,9 +92,10 @@ kvm_clock_get_wallclock(void *arg) } static void -kvm_clock_system_time_enable(struct kvm_clock_softc *sc) +kvm_clock_system_time_enable(struct kvm_clock_softc *sc, const cpuset_t *cpus) { - smp_rendezvous(NULL, kvm_clock_system_time_enable_pcpu, NULL, sc); + smp_rendezvous_cpus(*cpus, NULL, kvm_clock_system_time_enable_pcpu, + NULL, sc); } static void @@ -104,6 +109,32 @@ kvm_clock_system_time_enable_pcpu(void *arg) wrmsr(sc->msr_tc, vtophys(&(sc->timeinfos)[curcpu]) | 1); } +#ifndef EARLY_AP_STARTUP +static void +kvm_clock_init_smp(void *arg __unused) +{ + devclass_t kvm_clock_devclass; + cpuset_t cpus; + struct kvm_clock_softc *sc; + + kvm_clock_devclass = devclass_find(KVM_CLOCK_DEVNAME); + sc = devclass_get_softc(kvm_clock_devclass, 0); + if (sc == NULL || mp_ncpus == 1) + return; + + /* + * Register with the hypervisor on all CPUs except the one that + * registered in kvm_clock_attach(). + */ + cpus = all_cpus; + KASSERT(CPU_ISSET(sc->firstcpu, &cpus), + ("%s: invalid first CPU %d", __func__, sc->firstcpu)); + CPU_CLR(sc->firstcpu, &cpus); + kvm_clock_system_time_enable(sc, &cpus); +} +SYSINIT(kvm_clock, SI_SUB_SMP, SI_ORDER_ANY, kvm_clock_init_smp, NULL); +#endif + static void kvm_clock_identify(driver_t *driver, device_t parent) { @@ -150,7 +181,12 @@ kvm_clock_attach(device_t dev) /* Set up 'struct pvclock_vcpu_time_info' page(s): */ sc->timeinfos = (struct pvclock_vcpu_time_info *)kmem_malloc(mp_ncpus * sizeof(struct pvclock_vcpu_time_info), M_WAITOK | M_ZERO); - kvm_clock_system_time_enable(sc); +#ifdef EARLY_AP_STARTUP + kvm_clock_system_time_enable(sc, &all_cpus); +#else + sc->firstcpu = curcpu; + kvm_clock_system_time_enable_pcpu(sc); +#endif /* * Init pvclock; register KVM clock wall clock, register KVM clock @@ -191,7 +227,7 @@ kvm_clock_resume(device_t dev) * conservatively assume that the system time must be re-inited in * suspend/resume scenarios. */ - kvm_clock_system_time_enable(device_get_softc(dev)); + kvm_clock_system_time_enable(device_get_softc(dev), &all_cpus); pvclock_resume(); inittodr(time_second); return (0);
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