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Message-Id: <1417762318.14674.0@smtp.corp.redhat.com>
Date: Fri, 05 Dec 2014 06:59:58 +0008
From: Jason Wang <jasowang@...hat.com>
To: "K. Y. Srinivasan" <kys@...rosoft.com>
Cc: gregkh@...uxfoundation.org, linux-kernel@...r.kernel.org,
devel@...uxdriverproject.org, olaf@...fle.de, apw@...onical.com,
"K. Y. Srinivasan" <kys@...rosoft.com>
Subject: Re: [PATCH V2 1/1] Drivers: hv: vmbus: Implement a clockevent
device
On Fri, Dec 5, 2014 at 10:18 AM, K. Y. Srinivasan <kys@...rosoft.com>
wrote:
> Implement a clockevent device based on the timer support
> available on Hyper-V.
>
> Signed-off-by: K. Y. Srinivasan <kys@...rosoft.com>
> ---
> arch/x86/include/uapi/asm/hyperv.h | 11 +++++
> drivers/hv/hv.c | 78
> ++++++++++++++++++++++++++++++++++++
> drivers/hv/hyperv_vmbus.h | 21 ++++++++++
> drivers/hv/vmbus_drv.c | 40 +++++++++++++++++-
> 4 files changed, 148 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..e2749c0 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..9e57c07 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 +579,37 @@ 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 (msg->header.message_type == HVMSG_NONE)
> + return;
Nitpick: caller has checked this.
>
> +
> + 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 +699,12 @@ 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
Reviewed-by: Jason Wang <jasowang@...hat.com>
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