linux-next: build failure after merge of the cxl tree

linux-next: build failure after merge of the cxl tree

[Stephen Rothwell]

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Hi all,

After merging the cxl tree, today's linux-next build (powerpc
ppc64_defconfig) failed like this:

drivers/nvdimm/label.c:750:32: error: 'uuid_to_nvdimm_cclass' defined but not used [-Werror=unused-function]
  750 | static enum nvdimm_claim_class uuid_to_nvdimm_cclass(uuid_t *uuid)
      |                                ^~~~~~~~~~~~~~~~~~~~~
cc1: all warnings being treated as errors

Caused by commit

  d68bc4b2338b ("libnvdimm/labels: Add address-abstraction uuid definitions")

Exposed by commit

  3fe617ccafd6 ("Enable '-Werror' by default for all kernel builds")

I have applied the following patch for today.

From: Stephen Rothwell <sfr@canb.auug.org.au>
Date: Mon, 6 Sep 2021 14:14:52 +1000
Subject: [PATCH] cxl: mark unused function as such

Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
---
 drivers/nvdimm/label.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/nvdimm/label.c b/drivers/nvdimm/label.c
index 7abeb1233404..175db14c7694 100644
--- a/drivers/nvdimm/label.c
+++ b/drivers/nvdimm/label.c
@@ -747,6 +747,7 @@ static enum nvdimm_claim_class guid_to_nvdimm_cclass(guid_t *guid)
 }
 
 /* CXL labels store UUIDs instead of GUIDs for the same data */
+__maybe_unused
 static enum nvdimm_claim_class uuid_to_nvdimm_cclass(uuid_t *uuid)
 {
 	if (uuid_equal(uuid, &nvdimm_btt_uuid))
-- 
2.32.0

-- 
Cheers,
Stephen Rothwell

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Re: linux-next: build failure after merge of the cxl tree

[Dan Williams]

On Sun, Sep 5, 2021 at 9:20 PM Stephen Rothwell <sfr@canb.auug.org.au> wrote:
>
> Hi all,
>
> After merging the cxl tree, today's linux-next build (powerpc
> ppc64_defconfig) failed like this:
>
> drivers/nvdimm/label.c:750:32: error: 'uuid_to_nvdimm_cclass' defined but not used [-Werror=unused-function]
>   750 | static enum nvdimm_claim_class uuid_to_nvdimm_cclass(uuid_t *uuid)
>       |                                ^~~~~~~~~~~~~~~~~~~~~
> cc1: all warnings being treated as errors
>
> Caused by commit
>
>   d68bc4b2338b ("libnvdimm/labels: Add address-abstraction uuid definitions")
>
> Exposed by commit
>
>   3fe617ccafd6 ("Enable '-Werror' by default for all kernel builds")
>
> I have applied the following patch for today.
>
> From: Stephen Rothwell <sfr@canb.auug.org.au>
> Date: Mon, 6 Sep 2021 14:14:52 +1000
> Subject: [PATCH] cxl: mark unused function as such
>
> Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
> ---
>  drivers/nvdimm/label.c | 1 +
>  1 file changed, 1 insertion(+)
>

Thanks for that Stephen. I'll just back this patch out and retry for
v5.16, it's not super critical.

linux-next: build failure after merge of the cxl tree

[Stephen Rothwell]

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Hi all,

After merging the cxl tree, today's linux-next build (x86_64 allmodconfig)
failed like this:

drivers/cxl/core/cdat.c: In function 'match_cxlrd_hb':
drivers/cxl/core/cdat.c:327:43: error: 'struct cxl_switch_decoder' has no member named 'target_lock'
  327 |                 seq = read_seqbegin(&cxlsd->target_lock);
      |                                           ^~
drivers/cxl/core/cdat.c:332:38: error: 'struct cxl_switch_decoder' has no member named 'target_lock'
  332 |         } while (read_seqretry(&cxlsd->target_lock, seq));
      |                                      ^~

Caused by commit

  185c1a489f87 ("cxl: Check qos_class validity on memdev probe")

interacting with commit

  5459e186a5c9 ("cxl/port: Fix missing target list lock")

from hte cls-fixes tree.

I have applied the following merge resolution for today.

From: Stephen Rothwell <sfr@canb.auug.org.au>
Date: Fri, 5 Jan 2024 15:44:24 +1100
Subject: [PATCH] fix up for "cxl: Check qos_class validity on memdev probe"

interacting with "cxl/port: Fix missing target list lock"

Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
---
 drivers/cxl/core/cdat.c | 14 ++++++--------
 1 file changed, 6 insertions(+), 8 deletions(-)

diff --git a/drivers/cxl/core/cdat.c b/drivers/cxl/core/cdat.c
index cd84d87f597a..10ac76bed477 100644
--- a/drivers/cxl/core/cdat.c
+++ b/drivers/cxl/core/cdat.c
@@ -8,6 +8,7 @@
 #include "cxlpci.h"
 #include "cxlmem.h"
 #include "cxl.h"
+#include "core.h"
 
 struct dsmas_entry {
 	struct range dpa_range;
@@ -315,7 +316,6 @@ static int match_cxlrd_hb(struct device *dev, void *data)
 	struct device *host_bridge = data;
 	struct cxl_switch_decoder *cxlsd;
 	struct cxl_root_decoder *cxlrd;
-	unsigned int seq;
 
 	if (!is_root_decoder(dev))
 		return 0;
@@ -323,13 +323,11 @@ static int match_cxlrd_hb(struct device *dev, void *data)
 	cxlrd = to_cxl_root_decoder(dev);
 	cxlsd = &cxlrd->cxlsd;
 
-	do {
-		seq = read_seqbegin(&cxlsd->target_lock);
-		for (int i = 0; i < cxlsd->nr_targets; i++) {
-			if (host_bridge == cxlsd->target[i]->dport_dev)
-				return 1;
-		}
-	} while (read_seqretry(&cxlsd->target_lock, seq));
+	guard(rwsem_read)(&cxl_region_rwsem);
+	for (int i = 0; i < cxlsd->nr_targets; i++) {
+		if (host_bridge == cxlsd->target[i]->dport_dev)
+			return 1;
+	}
 
 	return 0;
 }
-- 
2.43.0

-- 
Cheers,
Stephen Rothwell

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RE: linux-next: build failure after merge of the cxl tree

[Dan Williams]

Stephen Rothwell wrote:
> Hi all,
> 
> After merging the cxl tree, today's linux-next build (x86_64 allmodconfig)
> failed like this:
> 
> drivers/cxl/core/cdat.c: In function 'match_cxlrd_hb':
> drivers/cxl/core/cdat.c:327:43: error: 'struct cxl_switch_decoder' has no member named 'target_lock'
>   327 |                 seq = read_seqbegin(&cxlsd->target_lock);
>       |                                           ^~
> drivers/cxl/core/cdat.c:332:38: error: 'struct cxl_switch_decoder' has no member named 'target_lock'
>   332 |         } while (read_seqretry(&cxlsd->target_lock, seq));
>       |                                      ^~
> 
> Caused by commit
> 
>   185c1a489f87 ("cxl: Check qos_class validity on memdev probe")
> 
> interacting with commit
> 
>   5459e186a5c9 ("cxl/port: Fix missing target list lock")
> 
> from hte cls-fixes tree.
> 
> I have applied the following merge resolution for today.

Yup, this looks good, I will include a this merge in my next branch
going forward.

> 
> From: Stephen Rothwell <sfr@canb.auug.org.au>
> Date: Fri, 5 Jan 2024 15:44:24 +1100
> Subject: [PATCH] fix up for "cxl: Check qos_class validity on memdev probe"
> 
> interacting with "cxl/port: Fix missing target list lock"
> 
> Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
> ---
>  drivers/cxl/core/cdat.c | 14 ++++++--------
>  1 file changed, 6 insertions(+), 8 deletions(-)
> 
> diff --git a/drivers/cxl/core/cdat.c b/drivers/cxl/core/cdat.c
> index cd84d87f597a..10ac76bed477 100644
> --- a/drivers/cxl/core/cdat.c
> +++ b/drivers/cxl/core/cdat.c
> @@ -8,6 +8,7 @@
>  #include "cxlpci.h"
>  #include "cxlmem.h"
>  #include "cxl.h"
> +#include "core.h"
>  
>  struct dsmas_entry {
>  	struct range dpa_range;
> @@ -315,7 +316,6 @@ static int match_cxlrd_hb(struct device *dev, void *data)
>  	struct device *host_bridge = data;
>  	struct cxl_switch_decoder *cxlsd;
>  	struct cxl_root_decoder *cxlrd;
> -	unsigned int seq;
>  
>  	if (!is_root_decoder(dev))
>  		return 0;
> @@ -323,13 +323,11 @@ static int match_cxlrd_hb(struct device *dev, void *data)
>  	cxlrd = to_cxl_root_decoder(dev);
>  	cxlsd = &cxlrd->cxlsd;
>  
> -	do {
> -		seq = read_seqbegin(&cxlsd->target_lock);
> -		for (int i = 0; i < cxlsd->nr_targets; i++) {
> -			if (host_bridge == cxlsd->target[i]->dport_dev)
> -				return 1;
> -		}
> -	} while (read_seqretry(&cxlsd->target_lock, seq));
> +	guard(rwsem_read)(&cxl_region_rwsem);
> +	for (int i = 0; i < cxlsd->nr_targets; i++) {
> +		if (host_bridge == cxlsd->target[i]->dport_dev)
> +			return 1;
> +	}
>  
>  	return 0;
>  }
> -- 
> 2.43.0
> 
> -- 
> Cheers,
> Stephen Rothwell

linux-next: build failure after merge of the cxl tree

[Stephen Rothwell]

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Hi all,

After merging the cxl tree, today's linux-next build (htmldocs) failed
like this:

drivers/cxl/cxl.h:443: warning: Function parameter or struct member 'cache_size' not described in 'cxl_root_decoder'

Caused by commit

  8d41af0d378d ("cxl: Remove core/acpi.c and cxl core dependency on ACPI")

-- 
Cheers,
Stephen Rothwell

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Re: linux-next: build failure after merge of the cxl tree

[Stephen Rothwell]

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Hi all,

On Tue, 15 Jul 2025 18:49:35 +1000 Stephen Rothwell <sfr@canb.auug.org.au> wrote:
>
> After merging the cxl tree, today's linux-next build (htmldocs) failed
> like this:
> 
> drivers/cxl/cxl.h:443: warning: Function parameter or struct member 'cache_size' not described in 'cxl_root_decoder'
> 
> Caused by commit
> 
>   8d41af0d378d ("cxl: Remove core/acpi.c and cxl core dependency on ACPI")

This is only a warning (I ran the wrong helper script :-) ).

-- 
Cheers,
Stephen Rothwell

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[PATCH v2] cxl: Remove core/acpi.c and cxl core dependency on ACPI

[Robert Richter]

From Dave [1]:

"""
It was a mistake to introduce core/acpi.c and putting ACPI dependency on
cxl_core when adding the extended linear cache support.
"""

Current implementation calls hmat_get_extended_linear_cache_size() of
the ACPI subsystem. That external reference causes issue running
cxl_test as there is no way to "mock" that function and ignore it when
using cxl test.

Instead of working around that using cxlrd ops and extensively
expanding cxl_test code [1], just move HMAT calls out of the core
module to cxl_acpi. Implement this by adding a @cache_size member to
struct cxl_root_decoder. During initialization the cache size is
determined and added to the root decoder object in cxl_acpi. Later on
in cxl_core the cache_size parameter is used to setup extended linear
caching.

[1] https://patch.msgid.link/20250610172938.139428-1-dave.jiang@intel.com

[ dj: Remove core/acpi.o from tools/testing/cxl/Kbuild ]

Cc: Dave Jiang <dave.jiang@intel.com>
Signed-off-by: Robert Richter <rrichter@amd.com>
Reviewed-by: Alison Schofield <alison.schofield@intel.com>
Reviewed-by: Jonathan Cameron <jonathan.cameron@huawei.com>
Reviewed-by: Dave Jiang <dave.jiang@intel.com>
Link: https://patch.msgid.link/20250711151529.787470-1-rrichter@amd.com
Signed-off-by: Dave Jiang <dave.jiang@intel.com>
Signed-off-by: Robert Richter <rrichter@amd.com>
---
v2:
 * fixed linux-next build error (htmldocs)
---
 drivers/cxl/acpi.c        | 59 +++++++++++++++++++++++++++++++++++++++
 drivers/cxl/core/Makefile |  1 -
 drivers/cxl/core/acpi.c   | 11 --------
 drivers/cxl/core/core.h   |  2 --
 drivers/cxl/core/region.c |  7 +----
 drivers/cxl/cxl.h         |  2 ++
 tools/testing/cxl/Kbuild  |  1 -
 7 files changed, 62 insertions(+), 21 deletions(-)
 delete mode 100644 drivers/cxl/core/acpi.c

diff --git a/drivers/cxl/acpi.c b/drivers/cxl/acpi.c
index a1a99ec3f12c..712624cba2b6 100644
--- a/drivers/cxl/acpi.c
+++ b/drivers/cxl/acpi.c
@@ -335,6 +335,63 @@ static int add_or_reset_cxl_resource(struct resource *parent, struct resource *r
 	return rc;
 }
 
+static int cxl_acpi_set_cache_size(struct cxl_root_decoder *cxlrd)
+{
+	struct cxl_decoder *cxld = &cxlrd->cxlsd.cxld;
+	struct range *hpa = &cxld->hpa_range;
+	resource_size_t size = range_len(hpa);
+	resource_size_t start = hpa->start;
+	resource_size_t cache_size;
+	struct resource res;
+	int nid, rc;
+
+	res = DEFINE_RES(start, size, 0);
+	nid = phys_to_target_node(start);
+
+	rc = hmat_get_extended_linear_cache_size(&res, nid, &cache_size);
+	if (rc)
+		return rc;
+
+	/*
+	 * The cache range is expected to be within the CFMWS.
+	 * Currently there is only support cache_size == cxl_size. CXL
+	 * size is then half of the total CFMWS window size.
+	 */
+	size = size >> 1;
+	if (cache_size && size != cache_size) {
+		dev_warn(&cxld->dev,
+			 "Extended Linear Cache size %pa != CXL size %pa. No Support!",
+			 &cache_size, &size);
+		return -ENXIO;
+	}
+
+	cxlrd->cache_size = cache_size;
+
+	return 0;
+}
+
+static void cxl_setup_extended_linear_cache(struct cxl_root_decoder *cxlrd)
+{
+	int rc;
+
+	rc = cxl_acpi_set_cache_size(cxlrd);
+	if (!rc)
+		return;
+
+	if (rc != -EOPNOTSUPP) {
+		/*
+		 * Failing to support extended linear cache region resize does not
+		 * prevent the region from functioning. Only causes cxl list showing
+		 * incorrect region size.
+		 */
+		dev_warn(cxlrd->cxlsd.cxld.dev.parent,
+			 "Extended linear cache calculation failed rc:%d\n", rc);
+	}
+
+	/* Ignoring return code */
+	cxlrd->cache_size = 0;
+}
+
 DEFINE_FREE(put_cxlrd, struct cxl_root_decoder *,
 	    if (!IS_ERR_OR_NULL(_T)) put_device(&_T->cxlsd.cxld.dev))
 DEFINE_FREE(del_cxl_resource, struct resource *, if (_T) del_cxl_resource(_T))
@@ -394,6 +451,8 @@ static int __cxl_parse_cfmws(struct acpi_cedt_cfmws *cfmws,
 		ig = CXL_DECODER_MIN_GRANULARITY;
 	cxld->interleave_granularity = ig;
 
+	cxl_setup_extended_linear_cache(cxlrd);
+
 	if (cfmws->interleave_arithmetic == ACPI_CEDT_CFMWS_ARITHMETIC_XOR) {
 		if (ways != 1 && ways != 3) {
 			cxims_ctx = (struct cxl_cxims_context) {
diff --git a/drivers/cxl/core/Makefile b/drivers/cxl/core/Makefile
index 79e2ef81fde8..5ad8fef210b5 100644
--- a/drivers/cxl/core/Makefile
+++ b/drivers/cxl/core/Makefile
@@ -15,7 +15,6 @@ cxl_core-y += hdm.o
 cxl_core-y += pmu.o
 cxl_core-y += cdat.o
 cxl_core-y += ras.o
-cxl_core-y += acpi.o
 cxl_core-$(CONFIG_TRACING) += trace.o
 cxl_core-$(CONFIG_CXL_REGION) += region.o
 cxl_core-$(CONFIG_CXL_MCE) += mce.o
diff --git a/drivers/cxl/core/acpi.c b/drivers/cxl/core/acpi.c
deleted file mode 100644
index f13b4dae6ac5..000000000000
--- a/drivers/cxl/core/acpi.c
+++ /dev/null
@@ -1,11 +0,0 @@
-// SPDX-License-Identifier: GPL-2.0-only
-/* Copyright(c) 2024 Intel Corporation. All rights reserved. */
-#include <linux/acpi.h>
-#include "cxl.h"
-#include "core.h"
-
-int cxl_acpi_get_extended_linear_cache_size(struct resource *backing_res,
-					    int nid, resource_size_t *size)
-{
-	return hmat_get_extended_linear_cache_size(backing_res, nid, size);
-}
diff --git a/drivers/cxl/core/core.h b/drivers/cxl/core/core.h
index 6b78b10da3e1..2250c05cecc3 100644
--- a/drivers/cxl/core/core.h
+++ b/drivers/cxl/core/core.h
@@ -121,8 +121,6 @@ int cxl_port_get_switch_dport_bandwidth(struct cxl_port *port,
 int cxl_ras_init(void);
 void cxl_ras_exit(void);
 int cxl_gpf_port_setup(struct cxl_dport *dport);
-int cxl_acpi_get_extended_linear_cache_size(struct resource *backing_res,
-					    int nid, resource_size_t *size);
 
 #ifdef CONFIG_CXL_FEATURES
 struct cxl_feat_entry *
diff --git a/drivers/cxl/core/region.c b/drivers/cxl/core/region.c
index 91ff3a495fbd..08ac7f483562 100644
--- a/drivers/cxl/core/region.c
+++ b/drivers/cxl/core/region.c
@@ -3282,15 +3282,10 @@ static int cxl_extended_linear_cache_resize(struct cxl_region *cxlr,
 {
 	struct cxl_root_decoder *cxlrd = to_cxl_root_decoder(cxlr->dev.parent);
 	struct cxl_region_params *p = &cxlr->params;
-	int nid = phys_to_target_node(res->start);
 	resource_size_t size = resource_size(res);
 	resource_size_t cache_size, start;
-	int rc;
-
-	rc = cxl_acpi_get_extended_linear_cache_size(res, nid, &cache_size);
-	if (rc)
-		return rc;
 
+	cache_size = cxlrd->cache_size;
 	if (!cache_size)
 		return 0;
 
diff --git a/drivers/cxl/cxl.h b/drivers/cxl/cxl.h
index e7b66ca1d423..b3aab7c7d17f 100644
--- a/drivers/cxl/cxl.h
+++ b/drivers/cxl/cxl.h
@@ -423,6 +423,7 @@ typedef u64 (*cxl_hpa_to_spa_fn)(struct cxl_root_decoder *cxlrd, u64 hpa);
 /**
  * struct cxl_root_decoder - Static platform CXL address decoder
  * @res: host / parent resource for region allocations
+ * @cache_size: extended linear cache size if exists, otherwise zero
  * @region_id: region id for next region provisioning event
  * @hpa_to_spa: translate CXL host-physical-address to Platform system-physical-address
  * @platform_data: platform specific configuration data
@@ -432,6 +433,7 @@ typedef u64 (*cxl_hpa_to_spa_fn)(struct cxl_root_decoder *cxlrd, u64 hpa);
  */
 struct cxl_root_decoder {
 	struct resource *res;
+	resource_size_t cache_size;
 	atomic_t region_id;
 	cxl_hpa_to_spa_fn hpa_to_spa;
 	void *platform_data;
diff --git a/tools/testing/cxl/Kbuild b/tools/testing/cxl/Kbuild
index 31a2d73c963f..d07f14cb7aa4 100644
--- a/tools/testing/cxl/Kbuild
+++ b/tools/testing/cxl/Kbuild
@@ -62,7 +62,6 @@ cxl_core-y += $(CXL_CORE_SRC)/hdm.o
 cxl_core-y += $(CXL_CORE_SRC)/pmu.o
 cxl_core-y += $(CXL_CORE_SRC)/cdat.o
 cxl_core-y += $(CXL_CORE_SRC)/ras.o
-cxl_core-y += $(CXL_CORE_SRC)/acpi.o
 cxl_core-$(CONFIG_TRACING) += $(CXL_CORE_SRC)/trace.o
 cxl_core-$(CONFIG_CXL_REGION) += $(CXL_CORE_SRC)/region.o
 cxl_core-$(CONFIG_CXL_MCE) += $(CXL_CORE_SRC)/mce.o
-- 
2.39.5

Re: linux-next: build failure after merge of the cxl tree

[Dave Jiang]

On 7/15/25 1:57 AM, Stephen Rothwell wrote:
> Hi all,
> 
> On Tue, 15 Jul 2025 18:49:35 +1000 Stephen Rothwell <sfr@canb.auug.org.au> wrote:
>>
>> After merging the cxl tree, today's linux-next build (htmldocs) failed
>> like this:
>>
>> drivers/cxl/cxl.h:443: warning: Function parameter or struct member 'cache_size' not described in 'cxl_root_decoder'
>>
>> Caused by commit
>>
>>   8d41af0d378d ("cxl: Remove core/acpi.c and cxl core dependency on ACPI")
> 
> This is only a warning (I ran the wrong helper script :-) ).
> 
No worries. Should be fixed in the next linux-next pull.