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kvm_clock: KVM paravirtual clock support

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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
This commit is contained in:
Adam Fenn 2021-08-04 08:42:48 -07:00 committed by Konstantin Belousov
parent 0b3382b863
commit 6c69c6bb4c
9 changed files with 340 additions and 1 deletions
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3
sys/amd64/conf/GENERIC
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@ -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

3
sys/amd64/conf/MINIMAL
View File

@ -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.

3
sys/amd64/conf/NOTES
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@ -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

3
sys/conf/files.x86
View File

@ -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

240
sys/dev/kvm_clock/kvm_clock.c Normal file
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@ -0,0 +1,240 @@
/*-
* SPDX-License-Identifier: BSD-2-Clause-FreeBSD
*
* Copyright (c) 2014 Bryan Venteicher <bryanv@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);

3
sys/i386/conf/GENERIC
View File

@ -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

3
sys/i386/conf/MINIMAL
View File

@ -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

3
sys/i386/conf/NOTES
View File

@ -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

80
sys/x86/include/kvm.h Normal file
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@ -0,0 +1,80 @@
/*-
* SPDX-License-Identifier: BSD-2-Clause-FreeBSD
*
* Copyright (c) 2014 Bryan Venteicher <bryanv@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_ */