The CXL subsystem currently has no trace coverage. Debugging mailbox
command flow requires either printf or qemu_log_mask, neither of which
is well suited for following the dispatch path that is exercised by
every guest driver probe.
Introduce a dedicated trace-events file under hw/cxl/ and wire it into
the build via the trace_events_subdirs list in the top-level
meson.build. Add three trace points covering command entry, payload
validation, and handler completion in cxl_process_cci_message():
* cxl_mailbox_command - command entry (opcode, len_in)
* cxl_mailbox_invalid_payload - payload length check rejection
* cxl_mailbox_handler_return - handler completion with return code
and len_out
The early-exit paths for unimplemented commands, in-progress background
operations, and disabled media skip handler dispatch and are therefore
not paired with cxl_mailbox_handler_return; an absent return event for
a given cxl_mailbox_command identifies these cases in the trace stream.
Trace points use the cxl_ prefix so future patches in this subsystem
share a single namespace, allowing -trace 'cxl_*' to match all of them.
Signed-off-by: Junjie Cao <[email protected]>
---
hw/cxl/cxl-mailbox-utils.c | 5 +++++
hw/cxl/trace-events | 8 ++++++++
hw/cxl/trace.h | 4 ++++
meson.build | 1 +
4 files changed, 18 insertions(+)
create mode 100644 hw/cxl/trace-events
create mode 100644 hw/cxl/trace.h
diff --git a/hw/cxl/cxl-mailbox-utils.c b/hw/cxl/cxl-mailbox-utils.c
index d8ba7e8625..521b8c6334 100644
--- a/hw/cxl/cxl-mailbox-utils.c
+++ b/hw/cxl/cxl-mailbox-utils.c
@@ -27,6 +27,7 @@
#include "system/hostmem.h"
#include "qemu/range.h"
#include "qapi/qapi-types-cxl.h"
+#include "trace.h"
#define CXL_CAPACITY_MULTIPLIER (256 * MiB)
#define CXL_DC_EVENT_LOG_SIZE 8
@@ -4580,6 +4581,7 @@ int cxl_process_cci_message(CXLCCI *cci, uint8_t set,
uint8_t cmd,
CXLDeviceState *cxl_dstate;
*len_out = 0;
+ trace_cxl_mailbox_command((set << 8) | cmd, len_in);
cxl_cmd = &cci->cxl_cmd_set[set][cmd];
h = cxl_cmd->handler;
if (!h) {
@@ -4589,6 +4591,8 @@ int cxl_process_cci_message(CXLCCI *cci, uint8_t set,
uint8_t cmd,
}
if (len_in != cxl_cmd->in && cxl_cmd->in != ~0) {
+ trace_cxl_mailbox_invalid_payload((set << 8) | cmd, len_in,
+ cxl_cmd->in);
return CXL_MBOX_INVALID_PAYLOAD_LENGTH;
}
@@ -4642,6 +4646,7 @@ int cxl_process_cci_message(CXLCCI *cci, uint8_t set,
uint8_t cmd,
timer_mod(cci->bg.timer, now + CXL_MBOX_BG_UPDATE_FREQ);
}
+ trace_cxl_mailbox_handler_return((set << 8) | cmd, ret, *len_out);
return ret;
}
diff --git a/hw/cxl/trace-events b/hw/cxl/trace-events
new file mode 100644
index 0000000000..abca116ed3
--- /dev/null
+++ b/hw/cxl/trace-events
@@ -0,0 +1,8 @@
+# See docs/devel/tracing.rst for syntax documentation.
+#
+# SPDX-License-Identifier: GPL-2.0-or-later
+
+# cxl-mailbox-utils.c
+cxl_mailbox_command(uint16_t opcode, size_t len_in) "opcode=0x%04x len_in=%zu"
+cxl_mailbox_invalid_payload(uint16_t opcode, size_t len_in, size_t expected)
"opcode=0x%04x len_in=%zu expected=%zu"
+cxl_mailbox_handler_return(uint16_t opcode, int ret, size_t len_out)
"opcode=0x%04x ret=%d len_out=%zu"
diff --git a/hw/cxl/trace.h b/hw/cxl/trace.h
new file mode 100644
index 0000000000..84e79d50c0
--- /dev/null
+++ b/hw/cxl/trace.h
@@ -0,0 +1,4 @@
+/*
+ * SPDX-License-Identifier: GPL-2.0-or-later
+ */
+#include "trace/trace-hw_cxl.h"
diff --git a/meson.build b/meson.build
index 19e123423b..c229199d5d 100644
--- a/meson.build
+++ b/meson.build
@@ -3596,6 +3596,7 @@ if have_system
'hw/audio',
'hw/block',
'hw/char',
+ 'hw/cxl',
'hw/display',
'hw/dma',
'hw/fsi',
--
2.43.0
