Re: [NDCTL PATCH v3 0/3] ndctl: Add support of qos_class for CXL CLI

From: Dan Williams <dan.j.williams@intel.com>
To: Dave Jiang <dave.jiang@intel.com>,
	Dan Williams <dan.j.williams@intel.com>,
	<linux-cxl@vger.kernel.org>, <nvdimm@lists.linux.dev>
Cc: <vishal.l.verma@intel.com>
Subject: Re: [NDCTL PATCH v3 0/3] ndctl: Add support of qos_class for CXL CLI
Date: Thu, 25 Jan 2024 14:07:11 -0800	[thread overview]
Message-ID: <65b2db8fb7587_37ad29483@dwillia2-xfh.jf.intel.com.notmuch> (raw)
In-Reply-To: <b1d5d419-7625-4c88-bf9b-50736662f330@intel.com>

Dave Jiang wrote:
[..]
> > This needs changes to test/cxl-topology.sh to validate that the
> > qos_class file pops in the right place per and has prepopulated values
> > per cxl_test expectation.
> 
> Do we need to plumb cxl_test to support qos_class with mock functions?
> Currently cxl_test does not support qos_class under memdev due it not support
> CDAT, HMAT/SRAT, and any of the PCIe bandwidth/latency attributes. It only
> has root decoder qos_class exposed. 

Something is need to avoid basic failures like "attribute published at
wrong path", but it does not need to go through full CDAT emulation.

I would do something like the below where ops->cxl_endpoint_parse_cdat()
does not need to actually read any real HMAT or CDAT. All it needs to do
is fake a final cxl_dpa_perf result(s) into the right places to make the
sysfs attribute show up.

Then we can do driver shutdown and access testing with the attribute
code to get lockdep coverage and other basic checkout.

diff --git a/tools/testing/cxl/Kbuild b/tools/testing/cxl/Kbuild
index caff3834671f..030b388800f0 100644
--- a/tools/testing/cxl/Kbuild
+++ b/tools/testing/cxl/Kbuild
@@ -13,6 +13,7 @@ ldflags-y += --wrap=cxl_hdm_decode_init
 ldflags-y += --wrap=cxl_dvsec_rr_decode
 ldflags-y += --wrap=devm_cxl_add_rch_dport
 ldflags-y += --wrap=cxl_rcd_component_reg_phys
+ldflags-y += --wrap=cxl_endpoint_parse_cdat
 
 DRIVERS := ../../../drivers
 CXL_SRC := $(DRIVERS)/cxl
diff --git a/tools/testing/cxl/test/mock.c b/tools/testing/cxl/test/mock.c
index 1a61e68e3095..9133cae1f5c1 100644
--- a/tools/testing/cxl/test/mock.c
+++ b/tools/testing/cxl/test/mock.c
@@ -285,6 +285,19 @@ resource_size_t __wrap_cxl_rcd_component_reg_phys(struct device *dev,
 }
 EXPORT_SYMBOL_NS_GPL(__wrap_cxl_rcd_component_reg_phys, CXL);
 
+void __wrap_cxl_endpoint_parse_cdat(struct cxl_port *port)
+{
+       int index;
+       struct cxl_mock_ops *ops = get_cxl_mock_ops(&index);
+       struct cxl_memdev *cxlmd = to_cxl_memdev(port->uport_dev);
+
+       if (ops && ops->is_mock_dev(cxlmd->dev.parent))
+               ops->cxl_endpoint_parse_cdat(port);
+       else
+               cxl_endpoint_parse_cdat(port);
+       put_cxl_mock_ops(index);
+}
+
 MODULE_LICENSE("GPL v2");
 MODULE_IMPORT_NS(ACPI);
 MODULE_IMPORT_NS(CXL);
