cxl/hdm: Add 'mode' attribute to decoder objects

Recall that the Device Physical Address (DPA) space of a CXL Memory
Expander is potentially partitioned into a volatile and persistent
portion. A decoder maps a Host Physical Address (HPA) range to a DPA
range and that translation depends on the value of all previous (lower
instance number) decoders before the current one.

In preparation for allowing dynamic provisioning of regions, decoders
need an ABI to indicate which DPA partition a decoder targets. This ABI
needs to be prepared for the possibility that some other agent committed
and locked a decoder that spans the partition boundary.

Add 'decoderX.Y/mode' to endpoint decoders that indicates which
partition 'ram' / 'pmem' the decoder targets, or 'mixed' if the decoder
currently spans the partition boundary.

Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Link: https://lore.kernel.org/r/165603881967.551046.6007594190951596439.stgit@dwillia2-xfh
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
This commit is contained in:
Dan Williams 2022-05-23 12:15:35 -07:00
parent 9c57cde0dc
commit 2c8669033f
4 changed files with 55 additions and 0 deletions

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@ -190,3 +190,19 @@ Description:
found to support CDAT data. If it is present and the length of
the data is 0 reading the CDAT data failed. Otherwise the CDAT
data is reported.
What: /sys/bus/cxl/devices/decoderX.Y/mode
Date: May, 2022
KernelVersion: v5.20
Contact: linux-cxl@vger.kernel.org
Description:
(RO) When a CXL decoder is of devtype "cxl_decoder_endpoint" it
translates from a host physical address range, to a device local
address range. Device-local address ranges are further split
into a 'ram' (volatile memory) range and 'pmem' (persistent
memory) range. The 'mode' attribute emits one of 'ram', 'pmem',
'mixed', or 'none'. The 'mixed' indication is for error cases
when a decoder straddles the volatile/persistent partition
boundary, and 'none' indicates the decoder is not actively
decoding, or no DPA allocation policy has been set.

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@ -226,6 +226,16 @@ static int __cxl_dpa_reserve(struct cxl_endpoint_decoder *cxled,
cxled->dpa_res = res;
cxled->skip = skipped;
if (resource_contains(&cxlds->pmem_res, res))
cxled->mode = CXL_DECODER_PMEM;
else if (resource_contains(&cxlds->ram_res, res))
cxled->mode = CXL_DECODER_RAM;
else {
dev_dbg(dev, "decoder%d.%d: %pr mixed\n", port->id,
cxled->cxld.id, cxled->dpa_res);
cxled->mode = CXL_DECODER_MIXED;
}
return 0;
}

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@ -172,6 +172,25 @@ static ssize_t target_list_show(struct device *dev,
}
static DEVICE_ATTR_RO(target_list);
static ssize_t mode_show(struct device *dev, struct device_attribute *attr,
char *buf)
{
struct cxl_endpoint_decoder *cxled = to_cxl_endpoint_decoder(dev);
switch (cxled->mode) {
case CXL_DECODER_RAM:
return sysfs_emit(buf, "ram\n");
case CXL_DECODER_PMEM:
return sysfs_emit(buf, "pmem\n");
case CXL_DECODER_NONE:
return sysfs_emit(buf, "none\n");
case CXL_DECODER_MIXED:
default:
return sysfs_emit(buf, "mixed\n");
}
}
static DEVICE_ATTR_RO(mode);
static struct attribute *cxl_decoder_base_attrs[] = {
&dev_attr_start.attr,
&dev_attr_size.attr,
@ -222,6 +241,7 @@ static const struct attribute_group *cxl_decoder_switch_attribute_groups[] = {
static struct attribute *cxl_decoder_endpoint_attrs[] = {
&dev_attr_target_type.attr,
&dev_attr_mode.attr,
NULL,
};

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@ -241,16 +241,25 @@ struct cxl_decoder {
unsigned long flags;
};
enum cxl_decoder_mode {
CXL_DECODER_NONE,
CXL_DECODER_RAM,
CXL_DECODER_PMEM,
CXL_DECODER_MIXED,
};
/**
* struct cxl_endpoint_decoder - Endpoint / SPA to DPA decoder
* @cxld: base cxl_decoder_object
* @dpa_res: actively claimed DPA span of this decoder
* @skip: offset into @dpa_res where @cxld.hpa_range maps
* @mode: which memory type / access-mode-partition this decoder targets
*/
struct cxl_endpoint_decoder {
struct cxl_decoder cxld;
struct resource *dpa_res;
resource_size_t skip;
enum cxl_decoder_mode mode;
};
/**