Date: Wed, 3 Apr 2024 15:22:29 -0700
From: Ira Weiny <ira.weiny@...el.com>
To: Jonathan Cameron <Jonathan.Cameron@...wei.com>, <ira.weiny@...el.com>
CC: Dave Jiang <dave.jiang@...el.com>, Fan Ni <fan.ni@...sung.com>, "Navneet
 Singh" <navneet.singh@...el.com>, Dan Williams <dan.j.williams@...el.com>,
	Davidlohr Bueso <dave@...olabs.net>, Alison Schofield
	<alison.schofield@...el.com>, Vishal Verma <vishal.l.verma@...el.com>,
	<linux-btrfs@...r.kernel.org>, <linux-cxl@...r.kernel.org>,
	<linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 03/26] cxl/mem: Read dynamic capacity configuration from
 the device

Jonathan Cameron wrote:
> On Sun, 24 Mar 2024 16:18:06 -0700
> ira.weiny@...el.com wrote:
> 

[snip]

> > +
> > +	/* Check regions are in increasing DPA order */
> > +	if (index > 0) {
> > +		struct cxl_dc_region_info *prev_dcr = &mds->dc_region[index - 1];
> > +
> > +		if ((prev_dcr->base + prev_dcr->decode_len) > dcr->base) {
> > +			dev_err(dev,
> > +				"DPA ordering violation for DC region %d and %d\n",
> > +				index - 1, index);
> > +			return -EINVAL;
> > +		}
> > +	}
> > +
> > +	if (!IS_ALIGNED(dcr->base, SZ_256M) ||
> > +	    !IS_ALIGNED(dcr->base, dcr->blk_size)) {
> > +		dev_err(dev, "DC region %d invalid base %#llx blk size %#llx\n", index,
> 
> Odd choice of line wrap.  I'd drag index onto the line below.

fixed.

> 
> > +			dcr->base, dcr->blk_size);
> > +		return -EINVAL;
> > +	}
> > +
> > +	if (dcr->decode_len == 0 || dcr->len == 0 || dcr->decode_len < dcr->len ||
> > +	    !IS_ALIGNED(dcr->len, dcr->blk_size)) {
> > +		dev_err(dev, "DC region %d invalid length; decode %#llx len %#llx blk size %#llx\n",
> > +			index, dcr->decode_len, dcr->len, dcr->blk_size);
> > +		return -EINVAL;
> > +	}
> > +
> > +	if (dcr->blk_size == 0 || dcr->blk_size % 0x40 ||
> 
> Hmm. I thought we had a define for CXL 'cacheline' size, but can't find it now.
> If not we should add one (and find a better name than that).

Asking me to add a define is fine...  Asking me to name said define is...
The issue...  I am absolute rubbish at picking names...  :-/  ;-)  :-D

> 
> > +	    !is_power_of_2(dcr->blk_size)) {
> > +		dev_err(dev, "DC region %d invalid block size; %#llx\n",
> > +			index, dcr->blk_size);
> > +		return -EINVAL;
> > +	}
> > +
> > +	dev_dbg(dev,
> > +		"DC region %s DPA: %#llx LEN: %#llx BLKSZ: %#llx\n",
> > +		dcr->name, dcr->base, dcr->decode_len, dcr->blk_size);
> > +
> > +	return 0;
> > +}
> > +
> > +/* Returns the number of regions in dc_resp or -ERRNO */
> > +static int cxl_get_dc_config(struct cxl_memdev_state *mds, u8 start_region,
> > +			     struct cxl_mbox_get_dc_config_out *dc_resp,
> > +			     size_t dc_resp_size)
> > +{
> > +	struct cxl_mbox_get_dc_config_in get_dc = (struct cxl_mbox_get_dc_config_in) {
> > +		.region_count = CXL_MAX_DC_REGION,
> > +		.start_region_index = start_region,
> > +	};
> > +	struct cxl_mbox_cmd mbox_cmd = (struct cxl_mbox_cmd) {
> > +		.opcode = CXL_MBOX_OP_GET_DC_CONFIG,
> > +		.payload_in = &get_dc,
> > +		.size_in = sizeof(get_dc),
> > +		.size_out = dc_resp_size,
> > +		.payload_out = dc_resp,
> > +		.min_out = 1,
> > +	};
> > +	struct device *dev = mds->cxlds.dev;
> > +	int rc;
> > +
> > +	rc = cxl_internal_send_cmd(mds, &mbox_cmd);
> > +	if (rc < 0)
> > +		return rc;
> > +
> > +	rc = dc_resp->avail_region_count - start_region;
> > +
> > +	/*
> > +	 * The number of regions in the payload may have been truncated due to
> > +	 * payload_size limits; if so adjust the returned count to match.
> > +	 */
> > +	if (mbox_cmd.size_out < sizeof(*dc_resp))
> > +		rc = CXL_REGIONS_RETURNED(mbox_cmd.size_out);
> 
> Why not always return this?  If there was space, doesn't it equal
> the value set above anyway?

I've been looking at this more carefully and there is a bigger issue with
this.  I need to update this code to handle the regions_returned which was
added in the errata and get rid of this macro.

> 
> > +
> > +	dev_dbg(dev, "Read %d/%d DC regions\n", rc, dc_resp->avail_region_count);
> > +
> > +	return rc;
> > +}
> 
> > +/**
> > + * cxl_dev_dynamic_capacity_identify() - Reads the dynamic capacity
> > + *					 information from the device.
> > + * @mds: The memory device state
> > + *
> > + * Read Dynamic Capacity information from the device and populate the state
> > + * structures for later use.
> > + *
> > + * Return: 0 if identify was executed successfully, -ERRNO on error.
> > + */
> > +int cxl_dev_dynamic_capacity_identify(struct cxl_memdev_state *mds)
> > +{
> > +	size_t dc_resp_size = mds->payload_size;
> > +	struct device *dev = mds->cxlds.dev;
> > +	u8 start_region, i;
> > +	int rc = 0;
> 
> Is this used before being set?

nope...

> 
> > +
> > +	for (i = 0; i < CXL_MAX_DC_REGION; i++)
> > +		snprintf(mds->dc_region[i].name, CXL_DC_REGION_STRLEN, "<nil>");
> > +
> > +	/* Check GET_DC_CONFIG is supported by device */
> > +	if (!cxl_dcd_supported(mds)) {
> > +		dev_dbg(dev, "DCD not supported\n");
> > +		return 0;
> > +	}
> > +
> > +	struct cxl_mbox_get_dc_config_out *dc_resp __free(kfree) =
> > +					kvmalloc(dc_resp_size, GFP_KERNEL);
> > +	if (!dc_resp)
> > +		return -ENOMEM;
> > +
> > +	start_region = 0;
> > +	do {
> > +		int j;
> > +
> > +		rc = cxl_get_dc_config(mds, start_region, dc_resp, dc_resp_size);
> > +		if (rc < 0) {
> > +			dev_dbg(dev, "Failed to get DC config: %d\n", rc);
> > +			return rc;
> > +		}
> > +
> > +		mds->nr_dc_region += rc;
> > +
> > +		if (mds->nr_dc_region < 1 || mds->nr_dc_region > CXL_MAX_DC_REGION) {
> > +			dev_err(dev, "Invalid num of dynamic capacity regions %d\n",
> > +				mds->nr_dc_region);
> > +			return -EINVAL;
> > +		}
> > +
> > +		for (i = start_region, j = 0; i < mds->nr_dc_region; i++, j++) {
> > +			rc = cxl_dc_save_region_info(mds, i, &dc_resp->region[j]);
> > +			if (rc) {
> > +				dev_dbg(dev, "Failed to save region info: %d\n", rc);
> > +				return rc;
> > +			}
> > +		}
> > +
> > +		start_region = mds->nr_dc_region;
> > +
> > +	} while (mds->nr_dc_region < dc_resp->avail_region_count);
> > +
> > +	mds->dynamic_cap =
> > +		mds->dc_region[mds->nr_dc_region - 1].base +
> > +		mds->dc_region[mds->nr_dc_region - 1].decode_len -
> > +		mds->dc_region[0].base;
> > +	dev_dbg(dev, "Total dynamic capacity: %#llx\n", mds->dynamic_cap);
> > +
> > +	return 0;
> > +}
> > +EXPORT_SYMBOL_NS_GPL(cxl_dev_dynamic_capacity_identify, CXL);
> 
> 
> 
> > diff --git a/drivers/cxl/cxlmem.h b/drivers/cxl/cxlmem.h
> > index 79a67cff9143..4624cf612c1e 100644
> > --- a/drivers/cxl/cxlmem.h
> > +++ b/drivers/cxl/cxlmem.h
> 
> >  /**
> >   * struct cxl_memdev_state - Generic Type-3 Memory Device Class driver data
> >   *
> > @@ -467,6 +482,8 @@ struct cxl_dev_state {
> >   * @enabled_cmds: Hardware commands found enabled in CEL.
> >   * @exclusive_cmds: Commands that are kernel-internal only
> >   * @total_bytes: sum of all possible capacities
> > + * @static_cap: Sum of static RAM and PMEM capacities
> > + * @dynamic_cap: Complete DPA range occupied by DC regions
> >   * @volatile_only_bytes: hard volatile capacity
> >   * @persistent_only_bytes: hard persistent capacity
> >   * @partition_align_bytes: alignment size for partition-able capacity
> > @@ -474,6 +491,8 @@ struct cxl_dev_state {
> >   * @active_persistent_bytes: sum of hard + soft persistent
> >   * @next_volatile_bytes: volatile capacity change pending device reset
> >   * @next_persistent_bytes: persistent capacity change pending device reset
> 
> Looks like we have some ordering issues ram_perf and pmem_perf (at least)
> that we should fix up as a precursor. I sent a reply to the QoS patch
> that added these.

I see.  That will likely resolve out when I rebase.  But seems nothing to
be done for this patch and best left as a separate patch from this series.

> 
> > + * @nr_dc_region: number of DC regions implemented in the memory device
> > + * @dc_region: array containing info about the DC regions
> >   * @event: event log driver state
> >   * @poison: poison driver state info
> >   * @security: security driver state info
> > @@ -494,7 +513,10 @@ struct cxl_memdev_state {
> >  	DECLARE_BITMAP(dcd_cmds, CXL_DCD_ENABLED_MAX);
> >  	DECLARE_BITMAP(enabled_cmds, CXL_MEM_COMMAND_ID_MAX);
> >  	DECLARE_BITMAP(exclusive_cmds, CXL_MEM_COMMAND_ID_MAX);
> > +
> Trivial but this is an unrelated change and shouldn't be in this patch.
> 
> >  	u64 total_bytes;
> > +	u64 static_cap;
> > +	u64 dynamic_cap;
> >  	u64 volatile_only_bytes;
> >  	u64 persistent_only_bytes;
> >  	u64 partition_align_bytes;
> > @@ -506,6 +528,9 @@ struct cxl_memdev_state {
> >  	struct cxl_dpa_perf ram_perf;
> >  	struct cxl_dpa_perf pmem_perf;
> >  
> > +	u8 nr_dc_region;
> > +	struct cxl_dc_region_info dc_region[CXL_MAX_DC_REGION];
> > +
> >  	struct cxl_event_state event;
> >  	struct cxl_poison_state poison;
> >  	struct cxl_security_state security;
> 
> > +
> > +/* See CXL 3.0 Table 125 get dynamic capacity config Output Payload */
> > +struct cxl_mbox_get_dc_config_out {
> > +	u8 avail_region_count;
> > +	u8 rsvd[7];
> > +	struct cxl_dc_region_config {
> > +		__le64 region_base;
> > +		__le64 region_decode_length;
> > +		__le64 region_length;
> > +		__le64 region_block_size;
> > +		__le32 region_dsmad_handle;
> > +		u8 flags;
> > +		u8 rsvd[3];
> > +	} __packed region[];
> > +} __packed;
> > +#define CXL_DYNAMIC_CAPACITY_SANITIZE_ON_RELEASE_FLAG BIT(0)
> > +#define CXL_REGIONS_RETURNED(size_out) \
> > +	((size_out - 8) / sizeof(struct cxl_dc_region_config))
> 
> Can we make that 8 self documenting?
> offsetof(struct cxl_dc_region_config, region) perhaps?

As I said above I think this macro is wrong I'm adjusting to remove it.

Thanks,
Ira

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