hw/cxl/device: Timestamp implementation (8.2.9.3)

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>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Message-Id: <20220429144110.25167-10-Jonathan.Cameron@huawei.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

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 +109,46 @@ 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;
+    uint64_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 +160,8 @@ 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)

include/hw/cxl/cxl_device.h

@@ -111,6 +111,12 @@ 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;