Re: [PATCH v6 09/43] hw/cxl/device: Timestamp implementation (8.2.9.3)

[Alex Bennée]

Jonathan Cameron <Jonathan.Cameron@huawei.com> writes:

> From: Ben Widawsky <ben.widawsky@intel.com>
>
> Errata F4 to CXL 2.0 clarified the meaning of the timer as the
> sum of the value set with the timestamp set command and the number
> of nano seconds since it was last set.
>
> Signed-off-by: Ben Widawsky <ben.widawsky@intel.com>
> Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
> ---
>  hw/cxl/cxl-mailbox-utils.c  | 44 +++++++++++++++++++++++++++++++++++++
>  include/hw/cxl/cxl_device.h |  6 +++++
>  2 files changed, 50 insertions(+)
>
> diff --git a/hw/cxl/cxl-mailbox-utils.c b/hw/cxl/cxl-mailbox-utils.c
> index 8aa1b1e525..258285ab03 100644
> --- a/hw/cxl/cxl-mailbox-utils.c
> +++ b/hw/cxl/cxl-mailbox-utils.c
> @@ -44,6 +44,9 @@ enum {
>          #define CLEAR_RECORDS   0x1
>          #define GET_INTERRUPT_POLICY   0x2
>          #define SET_INTERRUPT_POLICY   0x3
> +    TIMESTAMP   = 0x03,
> +        #define GET           0x0
> +        #define SET           0x1
>  };
>  
>  /* 8.2.8.4.5.1 Command Return Codes */
> @@ -106,9 +109,48 @@ DEFINE_MAILBOX_HANDLER_NOP(events_clear_records);
>  DEFINE_MAILBOX_HANDLER_ZEROED(events_get_interrupt_policy, 4);
>  DEFINE_MAILBOX_HANDLER_NOP(events_set_interrupt_policy);
>  
> +/* 8.2.9.3.1 */
> +static ret_code cmd_timestamp_get(struct cxl_cmd *cmd,
> +                                  CXLDeviceState *cxl_dstate,
> +                                  uint16_t *len)
> +{
> +    uint64_t time, delta;
> +
> +    if (!cxl_dstate->timestamp.set) {
> +        *(uint64_t *)cmd->payload = 0;
> +        goto done;
> +    }
> +
> +    /* First find the delta from the last time the host set the time. */
> +    time = qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL);
> +    delta = time - cxl_dstate->timestamp.last_set;
> +
> +    /* Then adjust the actual time */
> +    stq_le_p(cmd->payload, cxl_dstate->timestamp.host_set + delta);
> +
> +done:

Again I think an unnecessary goto for want of:

 uin64_t final_time = 0;
 if (cxl_dstate->timestamp.set) {
    /* First find the delta from the last time the host set the time. */
    time = qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL);
    delta = time - cxl_dstate->timestamp.last_set;
    final_time = cxl_dstate->timestamp.host_set + delta;
 }

 /* Then adjust the actual time */
 stq_le_p(cmd->payload, final_time);


> +    *len = 8;
> +    return CXL_MBOX_SUCCESS;
> +}
> +
> +/* 8.2.9.3.2 */
> +static ret_code cmd_timestamp_set(struct cxl_cmd *cmd,
> +                                  CXLDeviceState *cxl_dstate,
> +                                  uint16_t *len)
> +{
> +    cxl_dstate->timestamp.set = true;
> +    cxl_dstate->timestamp.last_set = qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL);
> +
> +    cxl_dstate->timestamp.host_set = le64_to_cpu(*(uint64_t *)cmd->payload);
> +
> +    *len = 0;
> +    return CXL_MBOX_SUCCESS;
> +}
> +
>  static QemuUUID cel_uuid;
>  
>  #define IMMEDIATE_CONFIG_CHANGE (1 << 1)
> +#define IMMEDIATE_POLICY_CHANGE (1 << 3)
>  #define IMMEDIATE_LOG_CHANGE (1 << 4)
>  
>  static struct cxl_cmd cxl_cmd_set[256][256] = {
> @@ -120,6 +162,8 @@ static struct cxl_cmd cxl_cmd_set[256][256] = {
>          cmd_events_get_interrupt_policy, 0, 0 },
>      [EVENTS][SET_INTERRUPT_POLICY] = { "EVENTS_SET_INTERRUPT_POLICY",
>          cmd_events_set_interrupt_policy, 4, IMMEDIATE_CONFIG_CHANGE },
> +    [TIMESTAMP][GET] = { "TIMESTAMP_GET", cmd_timestamp_get, 0, 0 },
> +    [TIMESTAMP][SET] = { "TIMESTAMP_SET", cmd_timestamp_set, 8, 
> IMMEDIATE_POLICY_CHANGE },
>  };
>  
>  void cxl_process_mailbox(CXLDeviceState *cxl_dstate)
> diff --git a/include/hw/cxl/cxl_device.h b/include/hw/cxl/cxl_device.h
> index 7fd8d0f616..8102d2a813 100644
> --- a/include/hw/cxl/cxl_device.h
> +++ b/include/hw/cxl/cxl_device.h
> @@ -117,6 +117,12 @@ typedef struct cxl_device_state {
>          size_t cel_size;
>      };
>  
> +    struct {
> +        bool set;
> +        uint64_t last_set;
> +        uint64_t host_set;
> +    } timestamp;
> +
>      /* memory region for persistent memory, HDM */
>      uint64_t pmem_size;
>  } CXLDeviceState;

Otherwise:

Reviewed-by: Alex Bennée <alex.bennee@linaro.org>

-- 
Alex Bennée