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@vmware.com>
Signed-off-by: Vivek Thampi <vithampi@vmware.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/MAINTAINERS b/MAINTAINERS
index 8f27f40..2ec6a53 100644 (file)
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -17852,6 +17852,13 @@ 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@vmware.com>
+M:     "VMware, Inc." <pv-drivers@vmware.com>
+L:     netdev@vger.kernel.org
+S:     Supported
+F:     drivers/ptp/ptp_vmw.c
+
 VMWARE PVRDMA DRIVER
 M:     Adit Ranadive <aditr@vmware.com>
 M:     VMware PV-Drivers <pv-drivers@vmware.com>

diff --git a/drivers/ptp/Kconfig b/drivers/ptp/Kconfig
index 3b424ff..86400c7 100644 (file)
--- a/drivers/ptp/Kconfig
+++ b/drivers/ptp/Kconfig
@@ -139,4 +139,16 @@ 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 01ff7fc..7aff75f 100644 (file)
--- a/drivers/ptp/Makefile
+++ b/drivers/ptp/Makefile
@@ -14,3 +14,4 @@ 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-$(CONFIG_PTP_1588_CLOCK_IDT82P33)  += ptp_idt82p33.o
+obj-$(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 (file)
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");