Re: [PATCH v5 14/16] cxl/pci: Add trace logging for CXL PCIe Port RAS errors

Jonathan Cameron
2025-01-14T11:49:31Z

On Tue, 7 Jan 2025 08:38:50 -0600
Terry Bowman <terry.bowman@amd.com> wrote:

> The CXL drivers use kernel trace functions for logging endpoint and
> Restricted CXL host (RCH) Downstream Port RAS errors. Similar functionality
> is required for CXL Root Ports, CXL Downstream Switch Ports, and CXL
> Upstream Switch Ports.
>
> Introduce trace logging functions for both RAS correctable and
> uncorrectable errors specific to CXL PCIe Ports. Additionally, update
> the CXL Port Protocol Error handlers to invoke these new trace functions.
>
> Signed-off-by: Terry Bowman <terry.bowman@amd.com>
> Reviewed-by: Alejandro Lucero <alucerop@amd.com>
> Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
An example print in commit message would help understand what the tracepoints
look like.

Few more things inline following on from earlier comments.

Jonathan
> ---
> drivers/cxl/core/pci.c | 17 +++++++++++----
> drivers/cxl/core/trace.h | 47 ++++++++++++++++++++++++++++++++++++++++
> 2 files changed, 60 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/cxl/core/pci.c b/drivers/cxl/core/pci.c
> index 411834f7efe0..3e87fe54a1a2 100644
> --- a/drivers/cxl/core/pci.c
> +++ b/drivers/cxl/core/pci.c
> @@ -663,10 +663,15 @@ static void __cxl_handle_cor_ras(struct device *dev,
>
> addr = ras_base + CXL_RAS_CORRECTABLE_STATUS_OFFSET;
> status = readl(addr);
> - if (status & CXL_RAS_CORRECTABLE_STATUS_MASK) {
> - writel(status & CXL_RAS_CORRECTABLE_STATUS_MASK, addr);
> + if (!(status & CXL_RAS_CORRECTABLE_STATUS_MASK))
> + return;
> +
> + writel(status & CXL_RAS_CORRECTABLE_STATUS_MASK, addr);
> +
> + if (is_cxl_memdev(dev))
As below. Drag to earlier patch.
> trace_cxl_aer_correctable_error(to_cxl_memdev(dev), status);
> - }
> + else

and perhaps check it's a port mostly for documentation purposes.

> + trace_cxl_port_aer_correctable_error(dev, status);
> }
>
> static void cxl_handle_endpoint_cor_ras(struct cxl_dev_state *cxlds)
> @@ -724,7 +729,11 @@ static bool __cxl_handle_ras(struct device *dev, void __iomem *ras_base)
> }
>
> header_log_copy(ras_base, hl);
> - trace_cxl_aer_uncorrectable_error(to_cxl_memdev(dev), status, fe, hl);
> + if (is_cxl_memdev(dev))

As mentioned above, drag this if to the earlier patch.

> + trace_cxl_aer_uncorrectable_error(to_cxl_memdev(dev), status, fe, hl);
> + else

For documentation purposes mostly I'd be tempted to have an is_cxl_port() check
before calling the following.

> + trace_cxl_port_aer_uncorrectable_error(dev, status, fe, hl);
> +
> writel(status & CXL_RAS_UNCORRECTABLE_STATUS_MASK, addr);
>
> return true;
> diff --git a/drivers/cxl/core/trace.h b/drivers/cxl/core/trace.h
> index 8389a94adb1a..681e415ac8f5 100644
> --- a/drivers/cxl/core/trace.h
> +++ b/drivers/cxl/core/trace.h
> @@ -48,6 +48,34 @@
> { CXL_RAS_UC_IDE_RX_ERR, "IDE Rx Error" } \
> )
>
> +TRACE_EVENT(cxl_port_aer_uncorrectable_error,
> + TP_PROTO(struct device *dev, u32 status, u32 fe, u32 *hl),
> + TP_ARGS(dev, status, fe, hl),
> + TP_STRUCT__entry(
> + __string(devname, dev_name(dev))
> + __string(host, dev_name(dev->parent))
What is host in this case? Perhaps a comment.
> + __field(u32, status)
> + __field(u32, first_error)
> + __array(u32, header_log, CXL_HEADERLOG_SIZE_U32)
> + ),
> + TP_fast_assign(
> + __assign_str(devname);
> + __assign_str(host);
> + __entry->status = status;
> + __entry->first_error = fe;
> + /*
> + * Embed the 512B headerlog data for user app retrieval and
> + * parsing, but no need to print this in the trace buffer.
> + */
> + memcpy(__entry->header_log, hl, CXL_HEADERLOG_SIZE);
> + ),
> + TP_printk("device=%s host=%s status: '%s' first_error: '%s'",
> + __get_str(devname), __get_str(host),
> + show_uc_errs(__entry->status),
> + show_uc_errs(__entry->first_error)
> + )
> +);
> +
> TRACE_EVENT(cxl_aer_uncorrectable_error,
> TP_PROTO(const struct cxl_memdev *cxlmd, u32 status, u32 fe, u32 *hl),
> TP_ARGS(cxlmd, status, fe, hl),
> @@ -96,6 +124,25 @@ TRACE_EVENT(cxl_aer_uncorrectable_error,
> { CXL_RAS_CE_PHYS_LAYER_ERR, "Received Error From Physical Layer" } \
> )
>
> +TRACE_EVENT(cxl_port_aer_correctable_error,
> + TP_PROTO(struct device *dev, u32 status),
> + TP_ARGS(dev, status),
> + TP_STRUCT__entry(
> + __string(devname, dev_name(dev))
> + __string(host, dev_name(dev->parent))
> + __field(u32, status)
> + ),
> + TP_fast_assign(
> + __assign_str(devname);
> + __assign_str(host);
> + __entry->status = status;
> + ),
> + TP_printk("device=%s host=%s status='%s'",
> + __get_str(devname), __get_str(host),
> + show_ce_errs(__entry->status)
> + )
> +);
> +
> TRACE_EVENT(cxl_aer_correctable_error,
> TP_PROTO(const struct cxl_memdev *cxlmd, u32 status),
> TP_ARGS(cxlmd, status),