git: 6c69c6bb4c7f - main - kvm_clock: KVM paravirtual clock support
Konstantin Belousov
kostikbel at gmail.com
Sun Aug 29 04:03:58 UTC 2021
On Sun, Aug 29, 2021 at 03:52:11AM +0000, Colin Percival wrote:
> Will this be MFCed to stable/13 ? I'd really really like to have it in 13.1
> since it fixes a regression in EC2.
Yes I plan to.
I am not sure when: there was at least one report of a breakage under
vbox, and I did not get any feedback on HEAD. The patches sit on my
staging stable/13 branch FWIW.
>
> Colin Percival
>
> On 8/14/21 5:58 AM, Konstantin Belousov wrote:
> > The branch main has been updated by kib:
> >
> > URL: https://cgit.FreeBSD.org/src/commit/?id=6c69c6bb4c7ffde48b130df707799d4eca21ca9f
> >
> > commit 6c69c6bb4c7ffde48b130df707799d4eca21ca9f
> > Author: Adam Fenn <adam at fenn.io>
> > AuthorDate: 2021-08-04 15:42:48 +0000
> > Commit: Konstantin Belousov <kib at FreeBSD.org>
> > CommitDate: 2021-08-14 12:57:54 +0000
> >
> > kvm_clock: KVM paravirtual clock support
> >
> > Add support for the KVM paravirtual clock device.
> >
> > Sponsored by: Juniper Networks, Inc.
> > Sponsored by: Klara, Inc.
> > Reviewed by: kib
> > Differential Revision: https://reviews.freebsd.org/D29733
> > ---
> > sys/amd64/conf/GENERIC | 3 +
> > sys/amd64/conf/MINIMAL | 3 +
> > sys/amd64/conf/NOTES | 3 +
> > sys/conf/files.x86 | 3 +-
> > sys/dev/kvm_clock/kvm_clock.c | 240 ++++++++++++++++++++++++++++++++++++++++++
> > sys/i386/conf/GENERIC | 3 +
> > sys/i386/conf/MINIMAL | 3 +
> > sys/i386/conf/NOTES | 3 +
> > sys/x86/include/kvm.h | 80 ++++++++++++++
> > 9 files changed, 340 insertions(+), 1 deletion(-)
> >
> > diff --git a/sys/amd64/conf/GENERIC b/sys/amd64/conf/GENERIC
> > index f7b41919575d..78b5e0e299f6 100644
> > --- a/sys/amd64/conf/GENERIC
> > +++ b/sys/amd64/conf/GENERIC
> > @@ -376,6 +376,9 @@ device virtio_blk # VirtIO Block device
> > device virtio_scsi # VirtIO SCSI device
> > device virtio_balloon # VirtIO Memory Balloon device
> >
> > +# Linux KVM paravirtualization support
> > +device kvm_clock # KVM paravirtual clock driver
> > +
> > # HyperV drivers and enhancement support
> > device hyperv # HyperV drivers
> >
> > diff --git a/sys/amd64/conf/MINIMAL b/sys/amd64/conf/MINIMAL
> > index 14f91e6c8eaf..f724cbd2e3f1 100644
> > --- a/sys/amd64/conf/MINIMAL
> > +++ b/sys/amd64/conf/MINIMAL
> > @@ -131,6 +131,9 @@ device ether # Ethernet support
> > # Note that 'bpf' is required for DHCP.
> > device bpf # Berkeley packet filter
> >
> > +# Linux KVM paravirtualization support
> > +device kvm_clock # KVM paravirtual clock driver
> > +
> > # Xen HVM Guest Optimizations
> > # NOTE: XENHVM depends on xenpci and xentimer.
> > # They must be added or removed together.
> > diff --git a/sys/amd64/conf/NOTES b/sys/amd64/conf/NOTES
> > index 501ceaedb222..c1db8ef7512f 100644
> > --- a/sys/amd64/conf/NOTES
> > +++ b/sys/amd64/conf/NOTES
> > @@ -498,6 +498,9 @@ device virtio_balloon # VirtIO Memory Balloon device
> > device virtio_random # VirtIO Entropy device
> > device virtio_console # VirtIO Console device
> >
> > +# Linux KVM paravirtualization support
> > +device kvm_clock # KVM paravirtual clock driver
> > +
> > # Microsoft Hyper-V enhancement support
> > device hyperv # HyperV drivers
> >
> > diff --git a/sys/conf/files.x86 b/sys/conf/files.x86
> > index d1fc234c4182..d0cda2da8580 100644
> > --- a/sys/conf/files.x86
> > +++ b/sys/conf/files.x86
> > @@ -263,6 +263,7 @@ dev/isci/scil/scif_sas_task_request_state_handlers.c optional isci
> > dev/isci/scil/scif_sas_task_request_states.c optional isci
> > dev/isci/scil/scif_sas_timer.c optional isci
> > dev/itwd/itwd.c optional itwd
> > +dev/kvm_clock/kvm_clock.c optional kvm_clock
> > dev/qat/qat.c optional qat
> > dev/qat/qat_ae.c optional qat
> > dev/qat/qat_c2xxx.c optional qat
> > @@ -318,7 +319,7 @@ x86/x86/x86_mem.c optional mem
> > x86/x86/mp_x86.c optional smp
> > x86/x86/mp_watchdog.c optional mp_watchdog smp
> > x86/x86/nexus.c standard
> > -x86/x86/pvclock.c optional xenhvm
> > +x86/x86/pvclock.c optional kvm_clock | xenhvm
> > x86/x86/stack_machdep.c optional ddb | stack
> > x86/x86/tsc.c standard
> > x86/x86/ucode.c standard
> > diff --git a/sys/dev/kvm_clock/kvm_clock.c b/sys/dev/kvm_clock/kvm_clock.c
> > new file mode 100644
> > index 000000000000..1a76432e417d
> > --- /dev/null
> > +++ b/sys/dev/kvm_clock/kvm_clock.c
> > @@ -0,0 +1,240 @@
> > +/*-
> > + * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
> > + *
> > + * Copyright (c) 2014 Bryan Venteicher <bryanv at FreeBSD.org>
> > + * Copyright (c) 2021 Mathieu Chouquet-Stringer
> > + * Copyright (c) 2021 Juniper Networks, Inc.
> > + * Copyright (c) 2021 Klara, Inc.
> > + *
> > + * Redistribution and use in source and binary forms, with or without
> > + * modification, are permitted provided that the following conditions
> > + * are met:
> > + * 1. Redistributions of source code must retain the above copyright
> > + * notice, this list of conditions and the following disclaimer.
> > + * 2. Redistributions in binary form must reproduce the above copyright
> > + * notice, this list of conditions and the following disclaimer in the
> > + * documentation and/or other materials provided with the distribution.
> > + *
> > + * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
> > + * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
> > + * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
> > + * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
> > + * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
> > + * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
> > + * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
> > + * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
> > + * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
> > + * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
> > + * SUCH DAMAGE.
> > + */
> > +
> > +/*
> > + * Linux KVM paravirtual clock support
> > + *
> > + * References:
> > + * - [1] https://www.kernel.org/doc/html/latest/virt/kvm/cpuid.html
> > + * - [2] https://www.kernel.org/doc/html/latest/virt/kvm/msr.html
> > + */
> > +
> > +#include <sys/cdefs.h>
> > +__FBSDID("$FreeBSD$");
> > +
> > +#include <sys/param.h>
> > +#include <sys/bus.h>
> > +#include <sys/domainset.h>
> > +#include <sys/kernel.h>
> > +#include <sys/malloc.h>
> > +#include <sys/module.h>
> > +#include <sys/smp.h>
> > +
> > +#include <vm/vm.h>
> > +#include <vm/pmap.h>
> > +#include <vm/vm_extern.h>
> > +
> > +#include <machine/pvclock.h>
> > +#include <x86/kvm.h>
> > +
> > +#include "clock_if.h"
> > +
> > +#define KVM_CLOCK_DEVNAME "kvmclock"
> > +/*
> > + * Note: Chosen to be (1) above HPET's value (always 950), (2) above the TSC's
> > + * default value of 800, and (3) below the TSC's value when it supports the
> > + * "Invariant TSC" feature and is believed to be synchronized across all CPUs.
> > + */
> > +#define KVM_CLOCK_TC_QUALITY 975
> > +
> > +struct kvm_clock_softc {
> > + struct pvclock pvc;
> > + struct pvclock_wall_clock wc;
> > + struct pvclock_vcpu_time_info *timeinfos;
> > + u_int msr_tc;
> > + u_int msr_wc;
> > +};
> > +
> > +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 struct pvclock_wall_clock *
> > +kvm_clock_get_wallclock(void *arg)
> > +{
> > + struct kvm_clock_softc *sc = arg;
> > +
> > + wrmsr(sc->msr_wc, vtophys(&sc->wc));
> > + return (&sc->wc);
> > +}
> > +
> > +static void
> > +kvm_clock_system_time_enable(struct kvm_clock_softc *sc)
> > +{
> > + smp_rendezvous(NULL, kvm_clock_system_time_enable_pcpu, NULL, sc);
> > +}
> > +
> > +static void
> > +kvm_clock_system_time_enable_pcpu(void *arg)
> > +{
> > + struct kvm_clock_softc *sc = arg;
> > +
> > + /*
> > + * See [2]; the lsb of this MSR is the system time enable bit.
> > + */
> > + wrmsr(sc->msr_tc, vtophys(&(sc->timeinfos)[curcpu]) | 1);
> > +}
> > +
> > +static void
> > +kvm_clock_identify(driver_t *driver, device_t parent)
> > +{
> > + u_int regs[4];
> > +
> > + kvm_cpuid_get_features(regs);
> > + if ((regs[0] &
> > + (KVM_FEATURE_CLOCKSOURCE2 | KVM_FEATURE_CLOCKSOURCE)) == 0)
> > + return;
> > + if (device_find_child(parent, KVM_CLOCK_DEVNAME, -1))
> > + return;
> > + BUS_ADD_CHILD(parent, 0, KVM_CLOCK_DEVNAME, 0);
> > +}
> > +
> > +static int
> > +kvm_clock_probe(device_t dev)
> > +{
> > + device_set_desc(dev, "KVM paravirtual clock");
> > + return (BUS_PROBE_DEFAULT);
> > +}
> > +
> > +static int
> > +kvm_clock_attach(device_t dev)
> > +{
> > + u_int regs[4];
> > + struct kvm_clock_softc *sc = device_get_softc(dev);
> > + bool stable_flag_supported;
> > +
> > + /* Process KVM "features" CPUID leaf content: */
> > + kvm_cpuid_get_features(regs);
> > + if ((regs[0] & KVM_FEATURE_CLOCKSOURCE2) != 0) {
> > + sc->msr_tc = KVM_MSR_SYSTEM_TIME_NEW;
> > + sc->msr_wc = KVM_MSR_WALL_CLOCK_NEW;
> > + } else {
> > + KASSERT((regs[0] & KVM_FEATURE_CLOCKSOURCE) != 0,
> > + ("Clocksource feature flags disappeared since "
> > + "kvm_clock_identify: regs[0] %#0x.", regs[0]));
> > + sc->msr_tc = KVM_MSR_SYSTEM_TIME;
> > + sc->msr_wc = KVM_MSR_WALL_CLOCK;
> > + }
> > + stable_flag_supported =
> > + (regs[0] & KVM_FEATURE_CLOCKSOURCE_STABLE_BIT) != 0;
> > +
> > + /* 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);
> > +
> > + /*
> > + * Init pvclock; register KVM clock wall clock, register KVM clock
> > + * timecounter, and set up the requisite infrastructure for vDSO access
> > + * to this timecounter.
> > + * Regarding 'tc_flags': Since the KVM MSR documentation does not
> > + * specifically discuss suspend/resume scenarios, conservatively
> > + * leave 'TC_FLAGS_SUSPEND_SAFE' cleared and assume that the system
> > + * time must be re-inited in such cases.
> > + */
> > + sc->pvc.get_wallclock = kvm_clock_get_wallclock;
> > + sc->pvc.get_wallclock_arg = sc;
> > + 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);
> > + return (0);
> > +}
> > +
> > +static int
> > +kvm_clock_detach(device_t dev)
> > +{
> > + struct kvm_clock_softc *sc = device_get_softc(dev);
> > +
> > + return (pvclock_destroy(&sc->pvc));
> > +}
> > +
> > +static int
> > +kvm_clock_suspend(device_t dev)
> > +{
> > + return (0);
> > +}
> > +
> > +static int
> > +kvm_clock_resume(device_t dev)
> > +{
> > + /*
> > + * See note in 'kvm_clock_attach()' regarding 'TC_FLAGS_SUSPEND_SAFE';
> > + * conservatively assume that the system time must be re-inited in
> > + * suspend/resume scenarios.
> > + */
> > + kvm_clock_system_time_enable(device_get_softc(dev));
> > + pvclock_resume();
> > + inittodr(time_second);
> > + return (0);
> > +}
> > +
> > +static int
> > +kvm_clock_gettime(device_t dev, struct timespec *ts)
> > +{
> > + struct kvm_clock_softc *sc = device_get_softc(dev);
> > +
> > + pvclock_gettime(&sc->pvc, ts);
> > + return (0);
> > +}
> > +
> > +static int
> > +kvm_clock_settime(device_t dev, struct timespec *ts)
> > +{
> > + /*
> > + * Even though it is not possible to set the KVM clock's wall clock, to
> > + * avoid the possibility of periodic benign error messages from
> > + * 'settime_task_func()', report success rather than, e.g., 'ENODEV'.
> > + */
> > + return (0);
> > +}
> > +
> > +static device_method_t kvm_clock_methods[] = {
> > + DEVMETHOD(device_identify, kvm_clock_identify),
> > + DEVMETHOD(device_probe, kvm_clock_probe),
> > + DEVMETHOD(device_attach, kvm_clock_attach),
> > + DEVMETHOD(device_detach, kvm_clock_detach),
> > + DEVMETHOD(device_suspend, kvm_clock_suspend),
> > + DEVMETHOD(device_resume, kvm_clock_resume),
> > + /* clock interface */
> > + DEVMETHOD(clock_gettime, kvm_clock_gettime),
> > + DEVMETHOD(clock_settime, kvm_clock_settime),
> > +
> > + DEVMETHOD_END
> > +};
> > +
> > +static driver_t kvm_clock_driver = {
> > + KVM_CLOCK_DEVNAME,
> > + kvm_clock_methods,
> > + sizeof(struct kvm_clock_softc),
> > +};
> > +
> > +DRIVER_MODULE(kvm_clock, nexus, kvm_clock_driver, kvm_clock_devclass, 0, 0);
> > diff --git a/sys/i386/conf/GENERIC b/sys/i386/conf/GENERIC
> > index 86c062effd81..5447c452c4f7 100644
> > --- a/sys/i386/conf/GENERIC
> > +++ b/sys/i386/conf/GENERIC
> > @@ -337,6 +337,9 @@ device virtio_blk # VirtIO Block device
> > device virtio_scsi # VirtIO SCSI device
> > device virtio_balloon # VirtIO Memory Balloon device
> >
> > +# Linux KVM paravirtualization support
> > +device kvm_clock # KVM paravirtual clock driver
> > +
> > # HyperV drivers and enhancement support
> > # NOTE: HYPERV depends on hyperv. They must be added or removed together.
> > options HYPERV # Kernel support for HyperV drivers
> > diff --git a/sys/i386/conf/MINIMAL b/sys/i386/conf/MINIMAL
> > index 37b8e074ac65..9d735dbb0580 100644
> > --- a/sys/i386/conf/MINIMAL
> > +++ b/sys/i386/conf/MINIMAL
> > @@ -145,6 +145,9 @@ device gif # IPv6 and IPv4 tunneling
> > # Note that 'bpf' is required for DHCP.
> > device bpf # Berkeley packet filter
> >
> > +# Linux KVM paravirtualization support
> > +device kvm_clock # KVM paravirtual clock driver
> > +
> > # Xen HVM Guest Optimizations
> > # NOTE: XENHVM depends on xenpci. They must be added or removed together.
> > options XENHVM # Xen HVM kernel infrastructure
> > diff --git a/sys/i386/conf/NOTES b/sys/i386/conf/NOTES
> > index df9ff4fb3aed..27cebf0c48a0 100644
> > --- a/sys/i386/conf/NOTES
> > +++ b/sys/i386/conf/NOTES
> > @@ -719,6 +719,9 @@ device virtio_balloon # VirtIO Memory Balloon device
> > device virtio_random # VirtIO Entropy device
> > device virtio_console # VirtIO Console device
> >
> > +# Linux KVM paravirtualization support
> > +device kvm_clock # KVM paravirtual clock driver
> > +
> > options HYPERV
> > device hyperv # HyperV drivers
> >
> > diff --git a/sys/x86/include/kvm.h b/sys/x86/include/kvm.h
> > new file mode 100644
> > index 000000000000..beec6447d7d6
> > --- /dev/null
> > +++ b/sys/x86/include/kvm.h
> > @@ -0,0 +1,80 @@
> > +/*-
> > + * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
> > + *
> > + * Copyright (c) 2014 Bryan Venteicher <bryanv at FreeBSD.org>
> > + * Copyright (c) 2021 Mathieu Chouquet-Stringer
> > + * Copyright (c) 2021 Juniper Networks, Inc.
> > + * Copyright (c) 2021 Klara, Inc.
> > + *
> > + * Redistribution and use in source and binary forms, with or without
> > + * modification, are permitted provided that the following conditions
> > + * are met:
> > + * 1. Redistributions of source code must retain the above copyright
> > + * notice, this list of conditions and the following disclaimer.
> > + * 2. Redistributions in binary form must reproduce the above copyright
> > + * notice, this list of conditions and the following disclaimer in the
> > + * documentation and/or other materials provided with the distribution.
> > + *
> > + * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
> > + * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
> > + * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
> > + * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
> > + * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
> > + * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
> > + * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
> > + * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
> > + * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
> > + * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
> > + * SUCH DAMAGE.
> > + *
> > + * $FreeBSD$
> > + */
> > +
> > +/*
> > + * Linux KVM paravirtualization: common definitions
> > + *
> > + * References:
> > + * - [1] https://www.kernel.org/doc/html/latest/virt/kvm/cpuid.html
> > + * - [2] https://www.kernel.org/doc/html/latest/virt/kvm/msr.html
> > + */
> > +
> > +#ifndef _X86_KVM_H_
> > +#define _X86_KVM_H_
> > +
> > +#include <sys/types.h>
> > +#include <sys/systm.h>
> > +
> > +#include <machine/md_var.h>
> > +
> > +#define KVM_CPUID_SIGNATURE 0x40000000
> > +#define KVM_CPUID_FEATURES_LEAF 0x40000001
> > +
> > +#define KVM_FEATURE_CLOCKSOURCE 0x00000001
> > +#define KVM_FEATURE_CLOCKSOURCE2 0x00000008
> > +#define KVM_FEATURE_CLOCKSOURCE_STABLE_BIT 0x01000000
> > +
> > +/* Deprecated: for the CLOCKSOURCE feature. */
> > +#define KVM_MSR_WALL_CLOCK 0x11
> > +#define KVM_MSR_SYSTEM_TIME 0x12
> > +
> > +#define KVM_MSR_WALL_CLOCK_NEW 0x4b564d00
> > +#define KVM_MSR_SYSTEM_TIME_NEW 0x4b564d01
> > +
> > +static inline bool
> > +kvm_cpuid_features_leaf_supported(void)
> > +{
> > + return (vm_guest == VM_GUEST_KVM &&
> > + KVM_CPUID_FEATURES_LEAF > hv_base &&
> > + KVM_CPUID_FEATURES_LEAF <= hv_high);
> > +}
> > +
> > +static inline void
> > +kvm_cpuid_get_features(u_int *regs)
> > +{
> > + if (!kvm_cpuid_features_leaf_supported())
> > + regs[0] = regs[1] = regs[2] = regs[3] = 0;
> > + else
> > + do_cpuid(KVM_CPUID_FEATURES_LEAF, regs);
> > +}
> > +
> > +#endif /* !_X86_KVM_H_ */
> >
>
> --
> Colin Percival
> Security Officer Emeritus, FreeBSD | The power to serve
> Founder, Tarsnap | www.tarsnap.com | Online backups for the truly paranoid
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