In general, vm inside will use virtual counter compered with host use
phyical counter. But in some special scenarios, like nested
virtualization, phyical counter maybe used by vm. A interface added in
ptp_kvm driver to offer a mechanism to let user choose which counter
should be return from host.
To use this feature, you should call PTP_EXTTS_REQUEST(2) ioctl with flag
set bit PTP_KVM_ARM_PHY_COUNTER in its argument then call
PTP_SYS_OFFSET_PRECISE(2) ioctl to get the cross timestamp and phyical
counter will return. If the bit not set or no call for PTP_EXTTS_REQUEST2,
virtual counter will return by default.
Signed-off-by: Jianyong Wu <jianyong.wu@xxxxxxx>
Suggested-by: Marc Zyngier <maz@xxxxxxxxxx>
---
drivers/clocksource/arm_arch_timer.c | 13 ++++++++++++-
drivers/ptp/ptp_chardev.c | 25 +++++++++++++++++++++++++
drivers/ptp/ptp_kvm_common.c | 7 ++++---
include/uapi/linux/ptp_clock.h | 4 +++-
4 files changed, 44 insertions(+), 5 deletions(-)
diff --git a/drivers/clocksource/arm_arch_timer.c b/drivers/clocksource/arm_arch_timer.c
index 06959b901b0d..75a3bb118201 100644
--- a/drivers/clocksource/arm_arch_timer.c
+++ b/drivers/clocksource/arm_arch_timer.c
@@ -1650,7 +1650,18 @@ int kvm_arch_ptp_get_crosststamp(unsigned long *cycle, struct timespec64 *ts,
struct arm_smccc_res hvc_res;
ktime_t ktime_overall;
- arm_smccc_1_1_invoke(ARM_SMCCC_VENDOR_HYP_KVM_PTP_FUNC_ID, &hvc_res);
+ /*
+ * an argument will be passed by a0 to determine weather virtual
+ * counter or phyical counter should be passed back.
+ */
+ if (ctx && *ctx)
+ arm_smccc_1_1_invoke(ARM_SMCCC_VENDOR_HYP_KVM_PTP_FUNC_ID,
+ ARM_SMCCC_VENDOR_HYP_KVM_PTP_PHY_FUNC_ID,
+ &hvc_res);
+ else
+ arm_smccc_1_1_invoke(ARM_SMCCC_VENDOR_HYP_KVM_PTP_FUNC_ID,
+ &hvc_res);
+
if ((int)(hvc_res.a0) < 0)
return -EOPNOTSUPP;
diff --git a/drivers/ptp/ptp_chardev.c b/drivers/ptp/ptp_chardev.c
index fef72f29f3c8..8b0a7b328bcd 100644
--- a/drivers/ptp/ptp_chardev.c
+++ b/drivers/ptp/ptp_chardev.c
@@ -123,6 +123,9 @@ long ptp_ioctl(struct posix_clock *pc, unsigned int cmd, unsigned long arg)
struct timespec64 ts;
int enable, err = 0;
+#ifdef CONFIG_ARM64
+ static long flag;
+#endif
switch (cmd) {
case PTP_CLOCK_GETCAPS:
@@ -149,6 +152,24 @@ long ptp_ioctl(struct posix_clock *pc, unsigned int cmd, unsigned long arg)
err = -EFAULT;
break;
}
+
+#ifdef CONFIG_ARM64
+ /*
+ * Just using this ioctl to tell kvm ptp driver to get PHC
+ * with physical counter, so if bit PTP_KVM_ARM_PHY_COUNTER
+ * is set then just exit directly.
+ * In most cases, we just need virtual counter from host and
+ * there is limited scenario using this to get physical counter
+ * in guest.
+ * Be careful to use this as there is no way to set it back
+ * unless you reinstall the module.
+ * This is only for arm64.
+ */
+ if (req.extts.flags & PTP_KVM_ARM_PHY_COUNTER) {
+ flag = 1;
+ break;
+ }
+#endif
if (cmd == PTP_EXTTS_REQUEST2) {
/* Tell the drivers to check the flags carefully. */
req.extts.flags |= PTP_STRICT_FLAGS;
@@ -235,7 +256,11 @@ long ptp_ioctl(struct posix_clock *pc, unsigned int cmd, unsigned long arg)
err = -EOPNOTSUPP;
break;
}
+#ifdef CONFIG_ARM64
+ err = ptp->info->getcrosststamp(ptp->info, &xtstamp, &flag);
+#else
err = ptp->info->getcrosststamp(ptp->info, &xtstamp, NULL);
+#endif
if (err)
break;
diff --git a/drivers/ptp/ptp_kvm_common.c b/drivers/ptp/ptp_kvm_common.c
index 4fdd8ab11a28..39367e230176 100644
--- a/drivers/ptp/ptp_kvm_common.c
+++ b/drivers/ptp/ptp_kvm_common.c
@@ -36,7 +36,7 @@ static int ptp_kvm_get_time_fn(ktime_t *device_time,
spin_lock(&kvm_ptp_lock);
preempt_disable_notrace();
- ret = kvm_arch_ptp_get_crosststamp(&cycle, &tspec, &cs);
+ ret = kvm_arch_ptp_get_crosststamp(&cycle, &tspec, &cs, ctx);
if (ret != 0) {
pr_err_ratelimited("clock pairing hypercall ret %lu\n", ret);
spin_unlock(&kvm_ptp_lock);
@@ -57,9 +57,10 @@ static int ptp_kvm_get_time_fn(ktime_t *device_time,
}
static int ptp_kvm_getcrosststamp(struct ptp_clock_info *ptp,
- struct system_device_crosststamp *xtstamp)
+ struct system_device_crosststamp *xtstamp,
+ long *flag)
{
- return get_device_system_crosststamp(ptp_kvm_get_time_fn, NULL,
+ return get_device_system_crosststamp(ptp_kvm_get_time_fn, flag,
NULL, xtstamp);
}
diff --git a/include/uapi/linux/ptp_clock.h b/include/uapi/linux/ptp_clock.h
index 9dc9d0079e98..71e388a82244 100644
--- a/include/uapi/linux/ptp_clock.h
+++ b/include/uapi/linux/ptp_clock.h
@@ -32,6 +32,7 @@
#define PTP_RISING_EDGE (1<<1)
#define PTP_FALLING_EDGE (1<<2)
#define PTP_STRICT_FLAGS (1<<3)
+#define PTP_KVM_ARM_PHY_COUNTER (1<<4)
#define PTP_EXTTS_EDGES (PTP_RISING_EDGE | PTP_FALLING_EDGE)
/*
@@ -40,7 +41,8 @@
#define PTP_EXTTS_VALID_FLAGS (PTP_ENABLE_FEATURE | \
PTP_RISING_EDGE | \
PTP_FALLING_EDGE | \
- PTP_STRICT_FLAGS)
+ PTP_STRICT_FLAGS | \
+ PTP_KVM_ARM_PHY_COUNTER)
/*
* flag fields valid for the original PTP_EXTTS_REQUEST ioctl.
--
2.17.1
