[PATCH V4 1/1] Drivers: hv: vmbus: Implement a clockevent device

From: K. Y. Srinivasan
Date: Sat Dec 06 2014 - 11:42:09 EST

Next message: Rickard Strandqvist: "[PATCH] mm: memcontrol.c: Cleaning up function that are not used anywhere"
Previous message: Martin van Es: "Re: frequent lockups in 3.18rc4"
Messages sorted by: [ date ] [ thread ] [ subject ] [ author ]

Implement a clockevent device based on the timer support available on
Hyper-V.
In this version of the patch I have addressed Jason's review comments.

Signed-off-by: K. Y. Srinivasan <kys@xxxxxxxxxxxxx>
Reviewed-by: Jason Wang <jasowang@xxxxxxxxxx>
---
arch/x86/include/uapi/asm/hyperv.h | 11 +++++
drivers/hv/hv.c | 78 ++++++++++++++++++++++++++++++++++++
drivers/hv/hyperv_vmbus.h | 21 ++++++++++
drivers/hv/vmbus_drv.c | 37 ++++++++++++++++-
4 files changed, 145 insertions(+), 2 deletions(-)

diff --git a/arch/x86/include/uapi/asm/hyperv.h b/arch/x86/include/uapi/asm/hyperv.h
index 462efe7..90c458e 100644
--- a/arch/x86/include/uapi/asm/hyperv.h
+++ b/arch/x86/include/uapi/asm/hyperv.h
@@ -187,6 +187,17 @@
#define HV_X64_MSR_SINT14 0x4000009E
#define HV_X64_MSR_SINT15 0x4000009F

+/*
+ * Synthetic Timer MSRs. Four timers per vcpu.
+ */
+#define HV_X64_MSR_STIMER0_CONFIG 0x400000B0
+#define HV_X64_MSR_STIMER0_COUNT 0x400000B1
+#define HV_X64_MSR_STIMER1_CONFIG 0x400000B2
+#define HV_X64_MSR_STIMER1_COUNT 0x400000B3
+#define HV_X64_MSR_STIMER2_CONFIG 0x400000B4
+#define HV_X64_MSR_STIMER2_COUNT 0x400000B5
+#define HV_X64_MSR_STIMER3_CONFIG 0x400000B6
+#define HV_X64_MSR_STIMER3_COUNT 0x400000B7

#define HV_X64_MSR_HYPERCALL_ENABLE 0x00000001
#define HV_X64_MSR_HYPERCALL_PAGE_ADDRESS_SHIFT 12
diff --git a/drivers/hv/hv.c b/drivers/hv/hv.c
index 3e4235c..50e51a5 100644
--- a/drivers/hv/hv.c
+++ b/drivers/hv/hv.c
@@ -28,7 +28,9 @@
#include <linux/hyperv.h>
#include <linux/version.h>
#include <linux/interrupt.h>
+#include <linux/clockchips.h>
#include <asm/hyperv.h>
+#include <asm/mshyperv.h>
#include "hyperv_vmbus.h"

/* The one and only */
@@ -37,6 +39,10 @@ struct hv_context hv_context = {
.hypercall_page = NULL,
};

+#define HV_TIMER_FREQUENCY (10 * 1000 * 1000) /* 100ns period */
+#define HV_MAX_MAX_DELTA_TICKS 0xffffffff
+#define HV_MIN_DELTA_TICKS 1
+
/*
* query_hypervisor_info - Get version info of the windows hypervisor
*/
@@ -144,6 +150,8 @@ int hv_init(void)
sizeof(int) * NR_CPUS);
memset(hv_context.event_dpc, 0,
sizeof(void *) * NR_CPUS);
+ memset(hv_context.clk_evt, 0,
+ sizeof(void *) * NR_CPUS);

max_leaf = query_hypervisor_info();

@@ -258,10 +266,63 @@ u16 hv_signal_event(void *con_id)
return status;
}

+static int hv_ce_set_next_event(unsigned long delta,
+ struct clock_event_device *evt)
+{
+ cycle_t current_tick;
+
+ WARN_ON(evt->mode != CLOCK_EVT_MODE_ONESHOT);
+
+ rdmsrl(HV_X64_MSR_TIME_REF_COUNT, current_tick);
+ current_tick += delta;
+ wrmsrl(HV_X64_MSR_STIMER0_COUNT, current_tick);
+ return 0;
+}
+
+static void hv_ce_setmode(enum clock_event_mode mode,
+ struct clock_event_device *evt)
+{
+ union hv_timer_config timer_cfg;
+
+ switch (mode) {
+ case CLOCK_EVT_MODE_PERIODIC:
+ /* unsupported */
+ break;
+
+ case CLOCK_EVT_MODE_ONESHOT:
+ timer_cfg.enable = 1;
+ timer_cfg.auto_enable = 1;
+ timer_cfg.sintx = VMBUS_MESSAGE_SINT;
+ wrmsrl(HV_X64_MSR_STIMER0_CONFIG, timer_cfg.as_uint64);
+ break;
+
+ case CLOCK_EVT_MODE_UNUSED:
+ case CLOCK_EVT_MODE_SHUTDOWN:
+ wrmsrl(HV_X64_MSR_STIMER0_COUNT, 0);
+ wrmsrl(HV_X64_MSR_STIMER0_CONFIG, 0);
+ break;
+ case CLOCK_EVT_MODE_RESUME:
+ break;
+ }
+}
+
+static void hv_init_clockevent_device(struct clock_event_device *dev, int cpu)
+{
+ dev->name = "Hyper-V clockevent";
+ dev->features = CLOCK_EVT_FEAT_ONESHOT;
+ dev->cpumask = cpumask_of(cpu);
+ dev->rating = 1000;
+ dev->owner = THIS_MODULE;
+
+ dev->set_mode = hv_ce_setmode;
+ dev->set_next_event = hv_ce_set_next_event;
+}
+

int hv_synic_alloc(void)
{
size_t size = sizeof(struct tasklet_struct);
+ size_t ced_size = sizeof(struct clock_event_device);
int cpu;

for_each_online_cpu(cpu) {
@@ -272,6 +333,13 @@ int hv_synic_alloc(void)
}
tasklet_init(hv_context.event_dpc[cpu], vmbus_on_event, cpu);

+ hv_context.clk_evt[cpu] = kzalloc(ced_size, GFP_ATOMIC);
+ if (hv_context.clk_evt[cpu] == NULL) {
+ pr_err("Unable to allocate clock event device\n");
+ goto err;
+ }
+ hv_init_clockevent_device(hv_context.clk_evt[cpu], cpu);
+
hv_context.synic_message_page[cpu] =
(void *)get_zeroed_page(GFP_ATOMIC);

@@ -305,6 +373,7 @@ err:
static void hv_synic_free_cpu(int cpu)
{
kfree(hv_context.event_dpc[cpu]);
+ kfree(hv_context.clk_evt[cpu]);
if (hv_context.synic_event_page[cpu])
free_page((unsigned long)hv_context.synic_event_page[cpu]);
if (hv_context.synic_message_page[cpu])
@@ -388,6 +457,15 @@ void hv_synic_init(void *arg)
hv_context.vp_index[cpu] = (u32)vp_index;

INIT_LIST_HEAD(&hv_context.percpu_list[cpu]);
+
+ /*
+ * Register the per-cpu clockevent source.
+ */
+ if (ms_hyperv.features & HV_X64_MSR_SYNTIMER_AVAILABLE)
+ clockevents_config_and_register(hv_context.clk_evt[cpu],
+ HV_TIMER_FREQUENCY,
+ HV_MIN_DELTA_TICKS,
+ HV_MAX_MAX_DELTA_TICKS);
return;
}

diff --git a/drivers/hv/hyperv_vmbus.h b/drivers/hv/hyperv_vmbus.h
index c386d8d..44b1c94 100644
--- a/drivers/hv/hyperv_vmbus.h
+++ b/drivers/hv/hyperv_vmbus.h
@@ -178,6 +178,23 @@ struct hv_message_header {
};
};

+/*
+ * Timer configuration register.
+ */
+union hv_timer_config {
+ u64 as_uint64;
+ struct {
+ u64 enable:1;
+ u64 periodic:1;
+ u64 lazy:1;
+ u64 auto_enable:1;
+ u64 reserved_z0:12;
+ u64 sintx:4;
+ u64 reserved_z1:44;
+ };
+};
+
+
/* Define timer message payload structure. */
struct hv_timer_message_payload {
u32 timer_index;
@@ -519,6 +536,10 @@ struct hv_context {
* buffer to post messages to the host.
*/
void *post_msg_page[NR_CPUS];
+ /*
+ * Support PV clockevent device.
+ */
+ struct clock_event_device *clk_evt[NR_CPUS];
};

extern struct hv_context hv_context;
diff --git a/drivers/hv/vmbus_drv.c b/drivers/hv/vmbus_drv.c
index 4d6b269..7488111 100644
--- a/drivers/hv/vmbus_drv.c
+++ b/drivers/hv/vmbus_drv.c
@@ -32,6 +32,7 @@
#include <linux/completion.h>
#include <linux/hyperv.h>
#include <linux/kernel_stat.h>
+#include <linux/clockchips.h>
#include <asm/hyperv.h>
#include <asm/hypervisor.h>
#include <asm/mshyperv.h>
@@ -578,6 +579,34 @@ static void vmbus_onmessage_work(struct work_struct *work)
kfree(ctx);
}

+void hv_process_timer_expiration(struct hv_message *msg, int cpu)
+{
+ struct clock_event_device *dev = hv_context.clk_evt[cpu];
+
+ if (dev->event_handler)
+ dev->event_handler(dev);
+
+ msg->header.message_type = HVMSG_NONE;
+
+ /*
+ * Make sure the write to MessageType (ie set to
+ * HVMSG_NONE) happens before we read the
+ * MessagePending and EOMing. Otherwise, the EOMing
+ * will not deliver any more messages since there is
+ * no empty slot
+ */
+ mb();
+
+ if (msg->header.message_flags.msg_pending) {
+ /*
+ * This will cause message queue rescan to
+ * possibly deliver another msg from the
+ * hypervisor
+ */
+ wrmsrl(HV_X64_MSR_EOM, 0);
+ }
+}
+
static void vmbus_on_msg_dpc(unsigned long data)
{
int cpu = smp_processor_id();
@@ -667,8 +696,12 @@ static void vmbus_isr(void)
msg = (struct hv_message *)page_addr + VMBUS_MESSAGE_SINT;

/* Check if there are actual msgs to be processed */
- if (msg->header.message_type != HVMSG_NONE)
- tasklet_schedule(&msg_dpc);
+ if (msg->header.message_type != HVMSG_NONE) {
+ if (msg->header.message_type == HVMSG_TIMER_EXPIRED)
+ hv_process_timer_expiration(msg, cpu);
+ else
+ tasklet_schedule(&msg_dpc);
+ }
}

/*
--
1.7.4.1

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/

Next message: Rickard Strandqvist: "[PATCH] mm: memcontrol.c: Cleaning up function that are not used anywhere"
Previous message: Martin van Es: "Re: frequent lockups in 3.18rc4"
Messages sorted by: [ date ] [ thread ] [ subject ] [ author ]