On Fri, 2024-03-01 at 15:36 -0700, Dave Jiang wrote:
> The CFMWS provides a QTG ID. The kernel driver creates a root decoder that
> represents the CFMWS. A qos_class attribute is exported via sysfs for the root
> decoder.
>
> One or more qos_class tokens are retrieved via QTG ID _DSM from the ACPI0017
> device for a CXL memory device. The input for the _DSM is the read and write
> latency and bandwidth for the path between the device and the CPU. The
> numbers are constructed by the kernel driver for the _DSM input. When a
> device is probed, QoS class tokens are retrieved. This is useful for a
> hot-plugged CXL memory device that does not have regions created.
>
> Add a QoS check during region creation. If --enforce-qos/-Q is set and
> the qos_class mismatches, the region creation will fail.
>
> Reviewed-by: Alison Schofield <alison.schofi...@intel.com>
> Signed-off-by: Dave Jiang <dave.ji...@intel.com>
> ---
> v8:
> - Add qos_class comparison in libcxl instead of user set flag. (Vishal)
> - Move check into validate_decoder(). (Vishal)
> ---
> Documentation/cxl/cxl-create-region.txt | 6 +++
> cxl/json.c | 6 +++
> cxl/lib/libcxl.c | 29 ++++++++++++++
> cxl/lib/libcxl.sym | 1 +
> cxl/libcxl.h | 1 +
> cxl/region.c | 53 ++++++++++++++++++++++++-
> 6 files changed, 95 insertions(+), 1 deletion(-)
>
> diff --git a/Documentation/cxl/cxl-create-region.txt
> b/Documentation/cxl/cxl-create-region.txt
> index f11a412bddfe..b244af60b8a6 100644
> --- a/Documentation/cxl/cxl-create-region.txt
> +++ b/Documentation/cxl/cxl-create-region.txt
> @@ -105,6 +105,12 @@ include::bus-option.txt[]
> supplied, the first cross-host bridge (if available), decoder that
> supports the largest interleave will be chosen.
>
> +-Q::
> +--enforce-qos::
> + Parameter to enforce qos_class mismatch failure. Region create operation
> + will fail of the qos_class of the root decoder and one of the memdev
> that
> + backs the region mismatches.
> +
> include::human-option.txt[]
>
> include::debug-option.txt[]
> diff --git a/cxl/json.c b/cxl/json.c
> index c8bd8c27447a..b9ed62abe0e2 100644
> --- a/cxl/json.c
> +++ b/cxl/json.c
> @@ -1238,6 +1238,12 @@ struct json_object *util_cxl_region_to_json(struct
> cxl_region *region,
> }
> }
>
> + if (!cxl_region_qos_class_matches(region)) {
> + jobj = json_object_new_boolean(true);
> + if (jobj)
> + json_object_object_add(jregion, "qos_class_mismatches",
> jobj);
Fairly minor but I think 'mismatched' (i.e. present continuous) for a
json attribute reads weirdly to me. Prefer it to be just
'qos_class_mismatch'
> + }
> +
> json_object_set_userdata(jregion, region, NULL);
>
>
> diff --git a/cxl/lib/libcxl.c b/cxl/lib/libcxl.c
> index 6c293f1dfc91..3ca0dca8db52 100644
> --- a/cxl/lib/libcxl.c
> +++ b/cxl/lib/libcxl.c
> @@ -414,6 +414,35 @@ CXL_EXPORT int cxl_region_is_enabled(struct cxl_region
> *region)
> return is_enabled(path);
> }
>
> +CXL_EXPORT bool cxl_region_qos_class_matches(struct cxl_region *region)
..and since the primary purpose of this API is to see if there is a
mismatch, I think it would be nice to invert the logic, and call it
cxl_region_qos_class_mismatch()
> +{
> + struct cxl_decoder *root_decoder = cxl_region_get_decoder(region);
> + struct cxl_memdev_mapping *mapping;
> +
> + cxl_mapping_foreach(region, mapping) {
> + struct cxl_decoder *decoder;
> + struct cxl_memdev *memdev;
> +
> + decoder = cxl_mapping_get_decoder(mapping);
> + if (!decoder)
> + continue;
> +
> + memdev = cxl_decoder_get_memdev(decoder);
> + if (!memdev)
> + continue;
> +
> + if (region->mode == CXL_DECODER_MODE_RAM) {
> + if (root_decoder->qos_class != memdev->ram_qos_class)
> + return false;
> + } else if (region->mode == CXL_DECODER_MODE_PMEM) {
> + if (root_decoder->qos_class != memdev->pmem_qos_class)
> + return false;
> + }
> + }
> +
> + return true;
> +}
> +
> CXL_EXPORT int cxl_region_disable(struct cxl_region *region)
> {
> const char *devname = cxl_region_get_devname(region);
> diff --git a/cxl/lib/libcxl.sym b/cxl/lib/libcxl.sym
> index 465c78dc6c70..a203b3ce3976 100644
> --- a/cxl/lib/libcxl.sym
> +++ b/cxl/lib/libcxl.sym
> @@ -285,4 +285,5 @@ global:
> cxl_root_decoder_get_qos_class;
> cxl_memdev_get_pmem_qos_class;
> cxl_memdev_get_ram_qos_class;
> + cxl_region_qos_class_matches;
> } LIBCXL_7;
> diff --git a/cxl/libcxl.h b/cxl/libcxl.h
> index a180f01cb05e..bd8e924844ff 100644
> --- a/cxl/libcxl.h
> +++ b/cxl/libcxl.h
> @@ -335,6 +335,7 @@ int cxl_region_clear_target(struct cxl_region *region,
> int position);
> int cxl_region_clear_all_targets(struct cxl_region *region);
> int cxl_region_decode_commit(struct cxl_region *region);
> int cxl_region_decode_reset(struct cxl_region *region);
> +bool cxl_region_qos_class_matches(struct cxl_region *region);
>
> #define cxl_region_foreach(decoder, region)
> \
> for (region = cxl_region_get_first(decoder); region != NULL; \
> diff --git a/cxl/region.c b/cxl/region.c
> index 3a762db4800e..735b3be7759b 100644
> --- a/cxl/region.c
> +++ b/cxl/region.c
> @@ -32,6 +32,7 @@ static struct region_params {
> bool force;
> bool human;
> bool debug;
> + bool qos_enforce;
Minor nit: just for parity, since the option is --enforce-qos, it would
be nice to call this enforce_qos (and down below as well).
> } param = {
> .ways = INT_MAX,
> .granularity = INT_MAX,
> @@ -49,6 +50,7 @@ struct parsed_params {
> const char **argv;
> struct cxl_decoder *root_decoder;
> enum cxl_decoder_mode mode;
> + bool qos_enforce;
> };
>
> enum region_actions {
> @@ -81,7 +83,8 @@ OPT_STRING('U', "uuid", ¶m.uuid, \
> "region uuid", "uuid for the new region (default: autogenerate)"), \
> OPT_BOOLEAN('m', "memdevs", ¶m.memdevs, \
> "non-option arguments are memdevs"), \
> -OPT_BOOLEAN('u', "human", ¶m.human, "use human friendly number formats")
> +OPT_BOOLEAN('u', "human", ¶m.human, "use human friendly number
> formats"), \
> +OPT_BOOLEAN('Q', "enforce-qos", ¶m.qos_enforce, "enforce of qos_class
> matching")
>
> static const struct option create_options[] = {
> BASE_OPTIONS(),
> @@ -360,6 +363,8 @@ static int parse_create_options(struct cxl_ctx *ctx, int
> count,
> }
> }
>
> + p->qos_enforce = param.qos_enforce;
> +
> return 0;
>
> err:
> @@ -423,10 +428,52 @@ static void collect_minsize(struct cxl_ctx *ctx, struct
> parsed_params *p)
> }
> }
>
> +static int create_region_validate_qos_class(struct parsed_params *p)
> +{
> + int root_qos_class;
> + int qos_class;
> + int i;
> +
> + if (!p->qos_enforce)
> + return 0;
> +
> + root_qos_class = cxl_root_decoder_get_qos_class(p->root_decoder);
> + if (root_qos_class == CXL_QOS_CLASS_NONE)
> + return 0;
> +
> + for (i = 0; i < p->ways; i++) {
> + struct json_object *jobj =
> + json_object_array_get_idx(p->memdevs, i);
> + struct cxl_memdev *memdev = json_object_get_userdata(jobj);
> +
> + if (p->mode == CXL_DECODER_MODE_RAM)
> + qos_class = cxl_memdev_get_ram_qos_class(memdev);
> + else
> + qos_class = cxl_memdev_get_pmem_qos_class(memdev);
> +
> + /* No qos_class entries. Possibly no kernel support */
> + if (qos_class == CXL_QOS_CLASS_NONE)
> + break;
> +
> + if (qos_class != root_qos_class) {
> + if (p->qos_enforce) {
> + log_err(&rl, "%s QoS Class mismatches %s\n",
Probably s/mismatches/mismatch/ here too.
> +
> cxl_decoder_get_devname(p->root_decoder),
> + cxl_memdev_get_devname(memdev));
> +
> + return -ENXIO;
> + }
> + }
> + }
> +
> + return 0;
> +}
> +
> static int validate_decoder(struct cxl_decoder *decoder,
> struct parsed_params *p)
> {
> const char *devname = cxl_decoder_get_devname(decoder);
> + int rc;
>
> switch(p->mode) {
> case CXL_DECODER_MODE_RAM:
> @@ -446,6 +493,10 @@ static int validate_decoder(struct cxl_decoder *decoder,
> return -EINVAL;
> }
>
> + rc = create_region_validate_qos_class(p);
> + if (rc)
> + return rc;
> +
> /* TODO check if the interleave config is possible under this decoder */
>
> return 0;
