PTP: add kvm PTP driver (a0e136d4) · Commits · 戴 / test

drivers/ptp/Kconfig

+12 −0

Original line number	Diff line number	Diff line
		@@ -90,4 +90,16 @@ config PTP_1588_CLOCK_PCH
		To compile this driver as a module, choose M here: the module
		will be called ptp_pch.

		config PTP_1588_CLOCK_KVM
		tristate "KVM virtual PTP clock"
		depends on PTP_1588_CLOCK
		depends on KVM_GUEST && X86
		default y
		help
		This driver adds support for using kvm infrastructure as a PTP
		clock. This clock is only useful if you are using KVM guests.

		To compile this driver as a module, choose M here: the module
		will be called ptp_kvm.

		endmenu

drivers/ptp/Makefile

+1 −0

Original line number	Diff line number	Diff line
		@@ -6,3 +6,4 @@ ptp-y := ptp_clock.o ptp_chardev.o ptp_sysfs.o
		obj-$(CONFIG_PTP_1588_CLOCK) += ptp.o
		obj-$(CONFIG_PTP_1588_CLOCK_IXP46X) += ptp_ixp46x.o
		obj-$(CONFIG_PTP_1588_CLOCK_PCH) += ptp_pch.o
		obj-$(CONFIG_PTP_1588_CLOCK_KVM) += ptp_kvm.o

drivers/ptp/ptp_kvm.c

0 → 100644

+200 −0

Original line number	Diff line number	Diff line
		/*
		* Virtual PTP 1588 clock for use with KVM guests
		*
		* Copyright (C) 2017 Red Hat Inc.
		*
		* This program is free software; you can redistribute it and/or modify
		* it under the terms of the GNU General Public License as published by
		* the Free Software Foundation; either version 2 of the License, or
		* (at your option) any later version.
		*
		* This program is distributed in the hope that it will be useful,
		* but WITHOUT ANY WARRANTY; without even the implied warranty of
		* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
		* GNU General Public License for more details.
		*
		*/
		#include <linux/device.h>
		#include <linux/err.h>
		#include <linux/init.h>
		#include <linux/kernel.h>
		#include <linux/module.h>
		#include <uapi/linux/kvm_para.h>
		#include <asm/kvm_para.h>
		#include <asm/pvclock.h>
		#include <asm/kvmclock.h>
		#include <uapi/asm/kvm_para.h>

		#include <linux/ptp_clock_kernel.h>

		struct kvm_ptp_clock {
		struct ptp_clock *ptp_clock;
		struct ptp_clock_info caps;
		};

		DEFINE_SPINLOCK(kvm_ptp_lock);

		static struct pvclock_vsyscall_time_info *hv_clock;

		static struct kvm_clock_pairing clock_pair;
		static phys_addr_t clock_pair_gpa;

		static int ptp_kvm_get_time_fn(ktime_t *device_time,
		struct system_counterval_t *system_counter,
		void *ctx)
		{
		unsigned long ret;
		struct timespec64 tspec;
		unsigned version;
		int cpu;
		struct pvclock_vcpu_time_info *src;

		spin_lock(&kvm_ptp_lock);

		preempt_disable_notrace();
		cpu = smp_processor_id();
		src = &hv_clock[cpu].pvti;

		do {
		/*
		* We are using a TSC value read in the hosts
		* kvm_hc_clock_pairing handling.
		* So any changes to tsc_to_system_mul
		* and tsc_shift or any other pvclock
		* data invalidate that measurement.
		*/
		version = pvclock_read_begin(src);

		ret = kvm_hypercall2(KVM_HC_CLOCK_PAIRING,
		clock_pair_gpa,
		KVM_CLOCK_PAIRING_WALLCLOCK);
		if (ret != 0) {
		pr_err_ratelimited("clock pairing hypercall ret %lu\n", ret);
		spin_unlock(&kvm_ptp_lock);
		preempt_enable_notrace();
		return -EOPNOTSUPP;
		}

		tspec.tv_sec = clock_pair.sec;
		tspec.tv_nsec = clock_pair.nsec;
		ret = __pvclock_read_cycles(src, clock_pair.tsc);
		} while (pvclock_read_retry(src, version));

		preempt_enable_notrace();

		system_counter->cycles = ret;
		system_counter->cs = &kvm_clock;

		*device_time = timespec64_to_ktime(tspec);

		spin_unlock(&kvm_ptp_lock);

		return 0;
		}

		static int ptp_kvm_getcrosststamp(struct ptp_clock_info *ptp,
		struct system_device_crosststamp *xtstamp)
		{
		return get_device_system_crosststamp(ptp_kvm_get_time_fn, NULL,
		NULL, xtstamp);
		}

		/*
		* PTP clock operations
		*/

		static int ptp_kvm_adjfreq(struct ptp_clock_info *ptp, s32 ppb)
		{
		return -EOPNOTSUPP;
		}

		static int ptp_kvm_adjtime(struct ptp_clock_info *ptp, s64 delta)
		{
		return -EOPNOTSUPP;
		}

		static int ptp_kvm_settime(struct ptp_clock_info *ptp,
		const struct timespec64 *ts)
		{
		return -EOPNOTSUPP;
		}

		static int ptp_kvm_gettime(struct ptp_clock_info ptp, struct timespec64 ts)
		{
		unsigned long ret;
		struct timespec64 tspec;

		spin_lock(&kvm_ptp_lock);

		ret = kvm_hypercall2(KVM_HC_CLOCK_PAIRING,
		clock_pair_gpa,
		KVM_CLOCK_PAIRING_WALLCLOCK);
		if (ret != 0) {
		pr_err_ratelimited("clock offset hypercall ret %lu\n", ret);
		spin_unlock(&kvm_ptp_lock);
		return -EOPNOTSUPP;
		}

		tspec.tv_sec = clock_pair.sec;
		tspec.tv_nsec = clock_pair.nsec;
		spin_unlock(&kvm_ptp_lock);

		memcpy(ts, &tspec, sizeof(struct timespec64));

		return 0;
		}

		static int ptp_kvm_enable(struct ptp_clock_info *ptp,
		struct ptp_clock_request *rq, int on)
		{
		return -EOPNOTSUPP;
		}

		static struct ptp_clock_info ptp_kvm_caps = {
		.owner = THIS_MODULE,
		.name = "KVM virtual PTP",
		.max_adj = 0,
		.n_ext_ts = 0,
		.n_pins = 0,
		.pps = 0,
		.adjfreq = ptp_kvm_adjfreq,
		.adjtime = ptp_kvm_adjtime,
		.gettime64 = ptp_kvm_gettime,
		.settime64 = ptp_kvm_settime,
		.enable = ptp_kvm_enable,
		.getcrosststamp = ptp_kvm_getcrosststamp,
		};

		/* module operations */

		static struct kvm_ptp_clock kvm_ptp_clock;

		static void __exit ptp_kvm_exit(void)
		{
		ptp_clock_unregister(kvm_ptp_clock.ptp_clock);
		}

		static int __init ptp_kvm_init(void)
		{
		clock_pair_gpa = slow_virt_to_phys(&clock_pair);
		hv_clock = pvclock_pvti_cpu0_va();

		if (!hv_clock)
		return -ENODEV;

		kvm_ptp_clock.caps = ptp_kvm_caps;

		kvm_ptp_clock.ptp_clock = ptp_clock_register(&kvm_ptp_clock.caps, NULL);

		if (IS_ERR(kvm_ptp_clock.ptp_clock))
		return PTR_ERR(kvm_ptp_clock.ptp_clock);

		return 0;
		}

		module_init(ptp_kvm_init);
		module_exit(ptp_kvm_exit);

		MODULE_AUTHOR("Marcelo Tosatti <mtosatti@redhat.com>");
		MODULE_DESCRIPTION("PTP clock using KVMCLOCK");
		MODULE_LICENSE("GPL");

Admin message