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kvmclock: Expose implied TSC frequency via sysctl

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An interface was added to derive an implied TSC frequency from pvclock
in 2015, but this interface was never exposed anywhere user-visible.

Reviewed by:	kib, bryanv
Differential Revision:	https://reviews.freebsd.org/D32974
This commit is contained in:
Colin Percival 2021-11-16 10:21:31 -08:00
parent 1580afcd6e
commit 57a8fa6f01
1 changed files with 26 additions and 0 deletions
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26
sys/dev/kvm_clock/kvm_clock.c
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@ -46,6 +46,7 @@ __FBSDID("$FreeBSD$");
#include <sys/malloc.h>
#include <sys/module.h>
#include <sys/smp.h>
#include <sys/sysctl.h>
#include <vm/vm.h>
#include <vm/pmap.h>
@ -77,6 +78,7 @@ 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_pcpu(void *arg);
static void kvm_clock_setup_sysctl(device_t);
static struct pvclock_wall_clock *
kvm_clock_get_wallclock(void *arg)
@ -166,6 +168,7 @@ kvm_clock_attach(device_t dev)
sc->pvc.timeinfos = sc->timeinfos;
sc->pvc.stable_flag_supported = stable_flag_supported;
pvclock_init(&sc->pvc, dev, KVM_CLOCK_DEVNAME, KVM_CLOCK_TC_QUALITY, 0);
kvm_clock_setup_sysctl(dev);
return (0);
}
@ -217,6 +220,29 @@ kvm_clock_settime(device_t dev, struct timespec *ts)
return (0);
}
static int
kvm_clock_tsc_freq_sysctl(SYSCTL_HANDLER_ARGS)
{
struct kvm_clock_softc *sc = oidp->oid_arg1;
uint64_t freq = pvclock_tsc_freq(sc->timeinfos);
return (sysctl_handle_64(oidp, &freq, 0, req));
}
static void
kvm_clock_setup_sysctl(device_t dev)
{
struct kvm_clock_softc *sc = device_get_softc(dev);
struct sysctl_ctx_list *ctx = device_get_sysctl_ctx(dev);
struct sysctl_oid *tree = device_get_sysctl_tree(dev);
struct sysctl_oid_list *child = SYSCTL_CHILDREN(tree);
SYSCTL_ADD_PROC(ctx, child, OID_AUTO, "tsc_freq",
CTLTYPE_U64 | CTLFLAG_RD | CTLFLAG_MPSAFE, sc, 0,
kvm_clock_tsc_freq_sysctl, "QU",
"Time Stamp Counter frequency");
}
static device_method_t kvm_clock_methods[] = {
DEVMETHOD(device_identify, kvm_clock_identify),
DEVMETHOD(device_probe, kvm_clock_probe),