[RFC PATCH v3 08/31] hw/cxl/device: Timestamp implementation (8.2.9.3)

Ben Widawsky
2021-02-02T01:01:08Z

Per spec, timestamp appears to be a free-running counter from a value
set by the host via the Set Timestamp command (0301h). There are
references to the epoch, which seem like a red herring. Therefore, the
implementation implements the timestamp as freerunning counter from the
last value that was issued by the Set Timestamp command.

Signed-off-by: Ben Widawsky <ben.widawsky@intel.com>
---
hw/cxl/cxl-mailbox-utils.c | 53 +++++++++++++++++++++++++++++++++++++
include/hw/cxl/cxl_device.h | 6 +++++
2 files changed, 59 insertions(+)

diff --git a/hw/cxl/cxl-mailbox-utils.c b/hw/cxl/cxl-mailbox-utils.c
index 7c939a1851..3d36614c0c 100644
--- a/hw/cxl/cxl-mailbox-utils.c
+++ b/hw/cxl/cxl-mailbox-utils.c
@@ -43,6 +43,9 @@ 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 */
@@ -117,8 +120,11 @@ define_mailbox_handler_zeroed(EVENTS_GET_RECORDS, 0x20);
define_mailbox_handler_nop(EVENTS_CLEAR_RECORDS);
define_mailbox_handler_zeroed(EVENTS_GET_INTERRUPT_POLICY, 4);
define_mailbox_handler_nop(EVENTS_SET_INTERRUPT_POLICY);
+declare_mailbox_handler(TIMESTAMP_GET);
+declare_mailbox_handler(TIMESTAMP_SET);

#define IMMEDIATE_CONFIG_CHANGE (1 << 1)
+#define IMMEDIATE_POLICY_CHANGE (1 << 3)
#define IMMEDIATE_LOG_CHANGE (1 << 4)

#define CXL_CMD(s, c, in, cel_effect) \
@@ -129,10 +135,57 @@ static struct cxl_cmd cxl_cmd_set[256][256] = {
CXL_CMD(EVENTS, CLEAR_RECORDS, ~0, IMMEDIATE_LOG_CHANGE),
CXL_CMD(EVENTS, GET_INTERRUPT_POLICY, 0, 0),
CXL_CMD(EVENTS, SET_INTERRUPT_POLICY, 4, IMMEDIATE_CONFIG_CHANGE),
+ CXL_CMD(TIMESTAMP, GET, 0, 0),
+ CXL_CMD(TIMESTAMP, SET, 8, IMMEDIATE_POLICY_CHANGE),
};

#undef CXL_CMD

+/*
+ * 8.2.9.3.1
+ */
+define_mailbox_handler(TIMESTAMP_GET)
+{
+ struct timespec ts;
+ uint64_t 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. */
+ clock_gettime(CLOCK_REALTIME, &ts);
+ delta = (ts.tv_sec * NANOSECONDS_PER_SECOND + ts.tv_nsec) -
+ cxl_dstate->timestamp.last_set;
+
+ /* Then adjust the actual time */
+ stq_le_p(cmd->payload, cxl_dstate->timestamp.host_set + delta);
+
+done:
+ *len = 8;
+ return CXL_MBOX_SUCCESS;
+}
+
+/*
+ * 8.2.9.3.2
+ */
+define_mailbox_handler(TIMESTAMP_SET)
+{
+ struct timespec ts;
+
+ clock_gettime(CLOCK_REALTIME, &ts);
+
+ cxl_dstate->timestamp.set = true;
+ cxl_dstate->timestamp.last_set =
+ ts.tv_sec * NANOSECONDS_PER_SECOND + ts.tv_nsec;
+
+ cxl_dstate->timestamp.host_set = le64_to_cpu(*(uint64_t *)cmd->payload);
+
+ *len = 0;
+ return CXL_MBOX_SUCCESS;
+}
+
QemuUUID cel_uuid;

void cxl_process_mailbox(CXLDeviceState *cxl_dstate)
diff --git a/include/hw/cxl/cxl_device.h b/include/hw/cxl/cxl_device.h
index 0cc5354ba4..ca5328a581 100644
--- a/include/hw/cxl/cxl_device.h
+++ b/include/hw/cxl/cxl_device.h
@@ -107,6 +107,12 @@ 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 */
MemoryRegion *pmem;

--
2.30.0