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Message-ID: <20200227135824.GA389099@sc2-cpbu2-b0737.eng.vmware.com>
Date: Thu, 27 Feb 2020 13:58:39 +0000
From: Vivek Thampi <vithampi@...are.com>
To: Richard Cochran <richardcochran@...il.com>
CC: Pv-drivers <Pv-drivers@...are.com>,
"netdev@...r.kernel.org" <netdev@...r.kernel.org>
Subject: [PATCH] ptp: add VMware virtual PTP clock driver
Add a PTP clock driver called ptp_vmw, for guests running on VMware ESXi
hypervisor. The driver attaches to a VMware virtual device called
"precision clock" that provides a mechanism for querying host system time.
Similar to existing virtual PTP clock drivers (e.g. ptp_kvm), ptp_vmw
utilizes the kernel's PTP hardware clock API to implement a clock device
that can be used as a reference in Chrony for synchronizing guest time with
host.
The driver is only applicable to x86 guests running in VMware virtual
machines with precision clock virtual device present. It uses a VMware
specific hypercall mechanism to read time from the device.
Reviewed-by: Thomas Hellstrom <thellstrom@...are.com>
Signed-off-by: Vivek Thampi <vithampi@...are.com>
---
MAINTAINERS | 7 +++
drivers/ptp/Kconfig | 12 +++++
drivers/ptp/Makefile | 1 +
drivers/ptp/ptp_vmw.c | 144 ++++++++++++++++++++++++++++++++++++++++++++++++++
4 files changed, 164 insertions(+)
create mode 100644 drivers/ptp/ptp_vmw.c
diff --git a/MAINTAINERS b/MAINTAINERS
index fcd79fc..871bb39 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -17854,6 +17854,13 @@ S: Supported
F: arch/x86/kernel/cpu/vmware.c
F: arch/x86/include/asm/vmware.h
+VMWARE VIRTUAL PTP CLOCK DRIVER
+M: Vivek Thampi <vithampi@...are.com>
+M: "VMware, Inc." <pv-drivers@...are.com>
+L: netdev@...r.kernel.org
+S: Supported
+F: drivers/ptp/ptp_vmw.c
+
VMWARE PVRDMA DRIVER
M: Adit Ranadive <aditr@...are.com>
M: VMware PV-Drivers <pv-drivers@...are.com>
diff --git a/drivers/ptp/Kconfig b/drivers/ptp/Kconfig
index 475c60d..7d7bb99 100644
--- a/drivers/ptp/Kconfig
+++ b/drivers/ptp/Kconfig
@@ -127,4 +127,16 @@ config PTP_1588_CLOCK_IDTCM
To compile this driver as a module, choose M here: the module
will be called ptp_clockmatrix.
+config PTP_1588_CLOCK_VMW
+ tristate "VMware virtual PTP clock"
+ depends on ACPI && HYPERVISOR_GUEST && X86
+ depends on PTP_1588_CLOCK
+ help
+ This driver adds support for using VMware virtual precision
+ clock device as a PTP clock. This is only useful in virtual
+ machines running on VMware virtual infrastructure.
+
+ To compile this driver as a module, choose M here: the module
+ will be called ptp_vmw.
+
endmenu
diff --git a/drivers/ptp/Makefile b/drivers/ptp/Makefile
index 8c83033..04b9acc 100644
--- a/drivers/ptp/Makefile
+++ b/drivers/ptp/Makefile
@@ -13,3 +13,4 @@ obj-$(CONFIG_PTP_1588_CLOCK_QORIQ) += ptp-qoriq.o
ptp-qoriq-y += ptp_qoriq.o
ptp-qoriq-$(CONFIG_DEBUG_FS) += ptp_qoriq_debugfs.o
obj-$(CONFIG_PTP_1588_CLOCK_IDTCM) += ptp_clockmatrix.o
+obj-$(CONFIG_PTP_1588_CLOCK_VMW) += ptp_vmw.o
diff --git a/drivers/ptp/ptp_vmw.c b/drivers/ptp/ptp_vmw.c
new file mode 100644
index 0000000..5dca26e
--- /dev/null
+++ b/drivers/ptp/ptp_vmw.c
@@ -0,0 +1,144 @@
+// SPDX-License-Identifier: GPL-2.0 OR BSD-2-Clause
+/*
+ * Copyright (C) 2020 VMware, Inc., Palo Alto, CA., USA
+ *
+ * PTP clock driver for VMware precision clock virtual device.
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/acpi.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/ptp_clock_kernel.h>
+#include <asm/hypervisor.h>
+#include <asm/vmware.h>
+
+#define VMWARE_MAGIC 0x564D5868
+#define VMWARE_CMD_PCLK(nr) ((nr << 16) | 97)
+#define VMWARE_CMD_PCLK_GETTIME VMWARE_CMD_PCLK(0)
+
+static struct acpi_device *ptp_vmw_acpi_device;
+static struct ptp_clock *ptp_vmw_clock;
+
+
+static int ptp_vmw_pclk_read(u64 *ns)
+{
+ u32 ret, nsec_hi, nsec_lo, unused1, unused2, unused3;
+
+ asm volatile (VMWARE_HYPERCALL :
+ "=a"(ret), "=b"(nsec_hi), "=c"(nsec_lo), "=d"(unused1),
+ "=S"(unused2), "=D"(unused3) :
+ "a"(VMWARE_MAGIC), "b"(0),
+ "c"(VMWARE_CMD_PCLK_GETTIME), "d"(0) :
+ "memory");
+
+ if (ret == 0)
+ *ns = ((u64)nsec_hi << 32) | nsec_lo;
+ return ret;
+}
+
+/*
+ * PTP clock ops.
+ */
+
+static int ptp_vmw_adjtime(struct ptp_clock_info *info, s64 delta)
+{
+ return -EOPNOTSUPP;
+}
+
+static int ptp_vmw_adjfreq(struct ptp_clock_info *info, s32 delta)
+{
+ return -EOPNOTSUPP;
+}
+
+static int ptp_vmw_gettime(struct ptp_clock_info *info, struct timespec64 *ts)
+{
+ u64 ns;
+
+ if (ptp_vmw_pclk_read(&ns) != 0)
+ return -EIO;
+ *ts = ns_to_timespec64(ns);
+ return 0;
+}
+
+static int ptp_vmw_settime(struct ptp_clock_info *info,
+ const struct timespec64 *ts)
+{
+ return -EOPNOTSUPP;
+}
+
+static int ptp_vmw_enable(struct ptp_clock_info *info,
+ struct ptp_clock_request *request, int on)
+{
+ return -EOPNOTSUPP;
+}
+
+static struct ptp_clock_info ptp_vmw_clock_info = {
+ .owner = THIS_MODULE,
+ .name = "ptp_vmw",
+ .max_adj = 0,
+ .adjtime = ptp_vmw_adjtime,
+ .adjfreq = ptp_vmw_adjfreq,
+ .gettime64 = ptp_vmw_gettime,
+ .settime64 = ptp_vmw_settime,
+ .enable = ptp_vmw_enable,
+};
+
+/*
+ * ACPI driver ops for VMware "precision clock" virtual device.
+ */
+
+static int ptp_vmw_acpi_add(struct acpi_device *device)
+{
+ ptp_vmw_clock = ptp_clock_register(&ptp_vmw_clock_info, NULL);
+ if (IS_ERR(ptp_vmw_clock)) {
+ pr_err("failed to register ptp clock\n");
+ return PTR_ERR(ptp_vmw_clock);
+ }
+
+ ptp_vmw_acpi_device = device;
+ return 0;
+}
+
+static int ptp_vmw_acpi_remove(struct acpi_device *device)
+{
+ ptp_clock_unregister(ptp_vmw_clock);
+ return 0;
+}
+
+static const struct acpi_device_id ptp_vmw_acpi_device_ids[] = {
+ { "VMW0005", 0 },
+ { "", 0 },
+};
+
+MODULE_DEVICE_TABLE(acpi, ptp_vmw_acpi_device_ids);
+
+static struct acpi_driver ptp_vmw_acpi_driver = {
+ .name = "ptp_vmw",
+ .ids = ptp_vmw_acpi_device_ids,
+ .ops = {
+ .add = ptp_vmw_acpi_add,
+ .remove = ptp_vmw_acpi_remove
+ },
+ .owner = THIS_MODULE
+};
+
+static int __init ptp_vmw_init(void)
+{
+ if (x86_hyper_type != X86_HYPER_VMWARE)
+ return -1;
+ return acpi_bus_register_driver(&ptp_vmw_acpi_driver);
+}
+
+static void __exit ptp_vmw_exit(void)
+{
+ acpi_bus_unregister_driver(&ptp_vmw_acpi_driver);
+}
+
+module_init(ptp_vmw_init);
+module_exit(ptp_vmw_exit);
+
+MODULE_DESCRIPTION("VMware virtual PTP clock driver");
+MODULE_AUTHOR("VMware, Inc.");
+MODULE_LICENSE("Dual BSD/GPL");
--
1.8.5.6
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