[PATCH v2] PCI: endpoint: pci-epf-test: Allow overriding default BAR sizes

[PATCH v2] PCI: endpoint: pci-epf-test: Allow overriding default BAR sizes

[Niklas Cassel]

Add bar{0,1,2,3,4,5}_size attributes in configfs, so that the user is not
restricted to run pci-epf-test with the hardcoded BAR size values defined
in pci-epf-test.c.

This code is shamelessly more or less copy pasted from pci-epf-vntb.c

Reviewed-by: Frank Li <Frank.Li@nxp.com>
Tested-by: Koichiro Den <den@valinux.co.jp>
Signed-off-by: Niklas Cassel <cassel@kernel.org>
---
Changes since v1:
-Rebased on branch controller/dwc since this branch contains changes
 to pci-epf-test.c which conflicted with V1 of this patch.
-Updated the documentation to show the current BAR sizes after other
 changes on branch controller/dwc.
-Picked up tags.

 Documentation/PCI/endpoint/pci-test-howto.rst | 16 ++++
 drivers/pci/endpoint/functions/pci-epf-test.c | 92 ++++++++++++++++++-
 2 files changed, 106 insertions(+), 2 deletions(-)

diff --git a/Documentation/PCI/endpoint/pci-test-howto.rst b/Documentation/PCI/endpoint/pci-test-howto.rst
index dd66858cde46..497251d53b12 100644
--- a/Documentation/PCI/endpoint/pci-test-howto.rst
+++ b/Documentation/PCI/endpoint/pci-test-howto.rst
@@ -84,6 +84,22 @@ device, the following commands can be used::
 	# echo 32 > functions/pci_epf_test/func1/msi_interrupts
 	# echo 2048 > functions/pci_epf_test/func1/msix_interrupts
 
+By default, pci-epf-test uses the following BAR sizes::
+
+	# grep . functions/pci_epf_test/func1/pci_epf_test.0/bar?_size
+	  functions/pci_epf_test/func1/pci_epf_test.0/bar0_size:131072
+	  functions/pci_epf_test/func1/pci_epf_test.0/bar1_size:131072
+	  functions/pci_epf_test/func1/pci_epf_test.0/bar2_size:131072
+	  functions/pci_epf_test/func1/pci_epf_test.0/bar3_size:131072
+	  functions/pci_epf_test/func1/pci_epf_test.0/bar4_size:131072
+	  functions/pci_epf_test/func1/pci_epf_test.0/bar5_size:1048576
+
+The user can override a default value using e.g.::
+	# echo 1048576 > functions/pci_epf_test/func1/pci_epf_test.0/bar1_size
+
+Note: Some endpoint controllers might have fixed size BARs, or reserved BARs,
+for such controllers, the corresponding BAR size in configfs will be ignored.
+
 
 Binding pci-epf-test Device to EP Controller
 --------------------------------------------
diff --git a/drivers/pci/endpoint/functions/pci-epf-test.c b/drivers/pci/endpoint/functions/pci-epf-test.c
index 1cc630a2ee75..e8dff291f116 100644
--- a/drivers/pci/endpoint/functions/pci-epf-test.c
+++ b/drivers/pci/endpoint/functions/pci-epf-test.c
@@ -72,6 +72,7 @@ static struct workqueue_struct *kpcitest_workqueue;
 struct pci_epf_test {
 	void			*reg[PCI_STD_NUM_BARS];
 	struct pci_epf		*epf;
+	struct config_group	group;
 	enum pci_barno		test_reg_bar;
 	size_t			msix_table_offset;
 	struct delayed_work	cmd_handler;
@@ -85,6 +86,7 @@ struct pci_epf_test {
 	bool			dma_private;
 	const struct pci_epc_features *epc_features;
 	struct pci_epf_bar	db_bar;
+	size_t			bar_size[PCI_STD_NUM_BARS];
 };
 
 struct pci_epf_test_reg {
@@ -111,7 +113,8 @@ static struct pci_epf_header test_header = {
 	.interrupt_pin	= PCI_INTERRUPT_INTA,
 };
 
-static size_t bar_size[] = { 131072, 131072, 131072, 131072, 131072, 1048576 };
+/* default BAR sizes, can be overridden by the user using configfs */
+static size_t default_bar_size[] = { 131072, 131072, 131072, 131072, 131072, 1048576 };
 
 static void pci_epf_test_dma_callback(void *param)
 {
@@ -1240,7 +1243,7 @@ static int pci_epf_test_alloc_space(struct pci_epf *epf)
 		if (epc_features->bar[bar].type == BAR_FIXED)
 			test_reg_size = epc_features->bar[bar].fixed_size;
 		else
-			test_reg_size = bar_size[bar];
+			test_reg_size = epf_test->bar_size[bar];
 
 		base = pci_epf_alloc_space(epf, test_reg_size, bar,
 					   epc_features, PRIMARY_INTERFACE);
@@ -1312,6 +1315,87 @@ static void pci_epf_test_unbind(struct pci_epf *epf)
 	pci_epf_test_free_space(epf);
 }
 
+#define PCI_EPF_TEST_BAR_SIZE_R(_name, _id)				\
+	static ssize_t pci_epf_test_##_name##_show(struct config_item *item,	\
+						   char *page)		\
+	{								\
+		struct config_group *group = to_config_group(item);	\
+		struct pci_epf_test *epf_test = container_of(group,	\
+					struct pci_epf_test, group);	\
+									\
+		return sprintf(page, "%zu\n", epf_test->bar_size[_id]);	\
+	}
+
+#define PCI_EPF_TEST_BAR_SIZE_W(_name, _id)				\
+	static ssize_t pci_epf_test_##_name##_store(struct config_item *item, \
+						    const char *page, size_t len) \
+	{								\
+		struct config_group *group = to_config_group(item);	\
+		struct pci_epf_test *epf_test = container_of(group,	\
+					struct pci_epf_test, group);	\
+		int val;						\
+		int ret;						\
+									\
+		ret = kstrtouint(page, 0, &val);			\
+		if (ret)						\
+			return ret;					\
+									\
+		if (!is_power_of_2(val))				\
+			return -EINVAL;					\
+									\
+		epf_test->bar_size[_id] = val;				\
+									\
+		return len;						\
+	}
+
+PCI_EPF_TEST_BAR_SIZE_R(bar0_size, BAR_0)
+PCI_EPF_TEST_BAR_SIZE_W(bar0_size, BAR_0)
+PCI_EPF_TEST_BAR_SIZE_R(bar1_size, BAR_1)
+PCI_EPF_TEST_BAR_SIZE_W(bar1_size, BAR_1)
+PCI_EPF_TEST_BAR_SIZE_R(bar2_size, BAR_2)
+PCI_EPF_TEST_BAR_SIZE_W(bar2_size, BAR_2)
+PCI_EPF_TEST_BAR_SIZE_R(bar3_size, BAR_3)
+PCI_EPF_TEST_BAR_SIZE_W(bar3_size, BAR_3)
+PCI_EPF_TEST_BAR_SIZE_R(bar4_size, BAR_4)
+PCI_EPF_TEST_BAR_SIZE_W(bar4_size, BAR_4)
+PCI_EPF_TEST_BAR_SIZE_R(bar5_size, BAR_5)
+PCI_EPF_TEST_BAR_SIZE_W(bar5_size, BAR_5)
+
+CONFIGFS_ATTR(pci_epf_test_, bar0_size);
+CONFIGFS_ATTR(pci_epf_test_, bar1_size);
+CONFIGFS_ATTR(pci_epf_test_, bar2_size);
+CONFIGFS_ATTR(pci_epf_test_, bar3_size);
+CONFIGFS_ATTR(pci_epf_test_, bar4_size);
+CONFIGFS_ATTR(pci_epf_test_, bar5_size);
+
+static struct configfs_attribute *pci_epf_test_attrs[] = {
+	&pci_epf_test_attr_bar0_size,
+	&pci_epf_test_attr_bar1_size,
+	&pci_epf_test_attr_bar2_size,
+	&pci_epf_test_attr_bar3_size,
+	&pci_epf_test_attr_bar4_size,
+	&pci_epf_test_attr_bar5_size,
+	NULL,
+};
+
+static const struct config_item_type pci_epf_test_group_type = {
+	.ct_attrs	= pci_epf_test_attrs,
+	.ct_owner	= THIS_MODULE,
+};
+
+static struct config_group *pci_epf_test_add_cfs(struct pci_epf *epf,
+						 struct config_group *group)
+{
+	struct pci_epf_test *epf_test = epf_get_drvdata(epf);
+	struct config_group *epf_group = &epf_test->group;
+	struct device *dev = &epf->dev;
+
+	config_group_init_type_name(epf_group, dev_name(dev),
+				    &pci_epf_test_group_type);
+
+	return epf_group;
+}
+
 static const struct pci_epf_device_id pci_epf_test_ids[] = {
 	{
 		.name = "pci_epf_test",
@@ -1324,6 +1408,7 @@ static int pci_epf_test_probe(struct pci_epf *epf,
 {
 	struct pci_epf_test *epf_test;
 	struct device *dev = &epf->dev;
+	enum pci_barno bar;
 
 	epf_test = devm_kzalloc(dev, sizeof(*epf_test), GFP_KERNEL);
 	if (!epf_test)
@@ -1331,6 +1416,8 @@ static int pci_epf_test_probe(struct pci_epf *epf,
 
 	epf->header = &test_header;
 	epf_test->epf = epf;
+	for (bar = BAR_0; bar < PCI_STD_NUM_BARS; bar++)
+		epf_test->bar_size[bar] = default_bar_size[bar];
 
 	INIT_DELAYED_WORK(&epf_test->cmd_handler, pci_epf_test_cmd_handler);
 
@@ -1343,6 +1430,7 @@ static int pci_epf_test_probe(struct pci_epf *epf,
 static const struct pci_epf_ops ops = {
 	.unbind	= pci_epf_test_unbind,
 	.bind	= pci_epf_test_bind,
+	.add_cfs = pci_epf_test_add_cfs,
 };
 
 static struct pci_epf_driver test_driver = {

base-commit: 0ebf8e7943e01b2c38c199228f51adbb89c02425
-- 
2.52.0

Re: [PATCH v2] PCI: endpoint: pci-epf-test: Allow overriding default BAR sizes

[Niklas Cassel]

On Wed, Jan 28, 2026 at 06:11:57PM +0100, Niklas Cassel wrote:
> @@ -1312,6 +1315,87 @@ static void pci_epf_test_unbind(struct pci_epf *epf)
>  	pci_epf_test_free_space(epf);
>  }
>  
> +#define PCI_EPF_TEST_BAR_SIZE_R(_name, _id)				\
> +	static ssize_t pci_epf_test_##_name##_show(struct config_item *item,	\
> +						   char *page)		\
> +	{								\
> +		struct config_group *group = to_config_group(item);	\
> +		struct pci_epf_test *epf_test = container_of(group,	\
> +					struct pci_epf_test, group);	\
> +									\
> +		return sprintf(page, "%zu\n", epf_test->bar_size[_id]);	\
> +	}
> +
> +#define PCI_EPF_TEST_BAR_SIZE_W(_name, _id)				\
> +	static ssize_t pci_epf_test_##_name##_store(struct config_item *item, \
> +						    const char *page, size_t len) \
> +	{								\
> +		struct config_group *group = to_config_group(item);	\
> +		struct pci_epf_test *epf_test = container_of(group,	\
> +					struct pci_epf_test, group);	\
> +		int val;						\
> +		int ret;						\
> +									\
> +		ret = kstrtouint(page, 0, &val);			\
> +		if (ret)						\
> +			return ret;					\
> +									\
> +		if (!is_power_of_2(val))				\
> +			return -EINVAL;					\
> +									\
> +		epf_test->bar_size[_id] = val;				\
> +									\
> +		return len;						\
> +	}
> +

This code does not handle:

# echo 1024 > functions/pci_epf_test/func1/pci_epf_test.0/bar1_size
# echo 0 > controllers/a40000000.pcie-ep/start
# echo 2048 > functions/pci_epf_test/func1/pci_epf_test.0/bar1_size
# echo 1 > controllers/a40000000.pcie-ep/start

Since backing memory for a BAR is allocated in .bind()

And set_bar() is called in .epc_init()

Setting/overriding the BAR size must be done before .bind(), i.e.
at probe() time.
(probe() is called when doing: mkdir functions/pci_epf_test/func1 in configfs)

Therefore, we must make sure that modifying bar*_size after the EPF has
been bound to a EPC will result in an error.

Will send a V3.


Kind regards,
Niklas

Re: [PATCH v2] PCI: endpoint: pci-epf-test: Allow overriding default BAR sizes

[Damien Le Moal]

On 1/29/26 02:11, Niklas Cassel wrote:
> Add bar{0,1,2,3,4,5}_size attributes in configfs, so that the user is not
> restricted to run pci-epf-test with the hardcoded BAR size values defined
> in pci-epf-test.c.
> 
> This code is shamelessly more or less copy pasted from pci-epf-vntb.c
> 
> Reviewed-by: Frank Li <Frank.Li@nxp.com>
> Tested-by: Koichiro Den <den@valinux.co.jp>
> Signed-off-by: Niklas Cassel <cassel@kernel.org>
> ---
> Changes since v1:
> -Rebased on branch controller/dwc since this branch contains changes
>  to pci-epf-test.c which conflicted with V1 of this patch.
> -Updated the documentation to show the current BAR sizes after other
>  changes on branch controller/dwc.
> -Picked up tags.
> 
>  Documentation/PCI/endpoint/pci-test-howto.rst | 16 ++++
>  drivers/pci/endpoint/functions/pci-epf-test.c | 92 ++++++++++++++++++-
>  2 files changed, 106 insertions(+), 2 deletions(-)
> 
> diff --git a/Documentation/PCI/endpoint/pci-test-howto.rst b/Documentation/PCI/endpoint/pci-test-howto.rst
> index dd66858cde46..497251d53b12 100644
> --- a/Documentation/PCI/endpoint/pci-test-howto.rst
> +++ b/Documentation/PCI/endpoint/pci-test-howto.rst
> @@ -84,6 +84,22 @@ device, the following commands can be used::
>  	# echo 32 > functions/pci_epf_test/func1/msi_interrupts
>  	# echo 2048 > functions/pci_epf_test/func1/msix_interrupts
>  
> +By default, pci-epf-test uses the following BAR sizes::
> +
> +	# grep . functions/pci_epf_test/func1/pci_epf_test.0/bar?_size
> +	  functions/pci_epf_test/func1/pci_epf_test.0/bar0_size:131072
> +	  functions/pci_epf_test/func1/pci_epf_test.0/bar1_size:131072
> +	  functions/pci_epf_test/func1/pci_epf_test.0/bar2_size:131072
> +	  functions/pci_epf_test/func1/pci_epf_test.0/bar3_size:131072
> +	  functions/pci_epf_test/func1/pci_epf_test.0/bar4_size:131072
> +	  functions/pci_epf_test/func1/pci_epf_test.0/bar5_size:1048576
> +
> +The user can override a default value using e.g.::
> +	# echo 1048576 > functions/pci_epf_test/func1/pci_epf_test.0/bar1_size
> +
> +Note: Some endpoint controllers might have fixed size BARs, or reserved BARs,
> +for such controllers, the corresponding BAR size in configfs will be ignored.
> +
>  
>  Binding pci-epf-test Device to EP Controller
>  --------------------------------------------
> diff --git a/drivers/pci/endpoint/functions/pci-epf-test.c b/drivers/pci/endpoint/functions/pci-epf-test.c
> index 1cc630a2ee75..e8dff291f116 100644
> --- a/drivers/pci/endpoint/functions/pci-epf-test.c
> +++ b/drivers/pci/endpoint/functions/pci-epf-test.c
> @@ -72,6 +72,7 @@ static struct workqueue_struct *kpcitest_workqueue;
>  struct pci_epf_test {
>  	void			*reg[PCI_STD_NUM_BARS];
>  	struct pci_epf		*epf;
> +	struct config_group	group;
>  	enum pci_barno		test_reg_bar;
>  	size_t			msix_table_offset;
>  	struct delayed_work	cmd_handler;
> @@ -85,6 +86,7 @@ struct pci_epf_test {
>  	bool			dma_private;
>  	const struct pci_epc_features *epc_features;
>  	struct pci_epf_bar	db_bar;
> +	size_t			bar_size[PCI_STD_NUM_BARS];
>  };
>  
>  struct pci_epf_test_reg {
> @@ -111,7 +113,8 @@ static struct pci_epf_header test_header = {
>  	.interrupt_pin	= PCI_INTERRUPT_INTA,
>  };
>  
> -static size_t bar_size[] = { 131072, 131072, 131072, 131072, 131072, 1048576 };
> +/* default BAR sizes, can be overridden by the user using configfs */
> +static size_t default_bar_size[] = { 131072, 131072, 131072, 131072, 131072, 1048576 };
>  
>  static void pci_epf_test_dma_callback(void *param)
>  {
> @@ -1240,7 +1243,7 @@ static int pci_epf_test_alloc_space(struct pci_epf *epf)
>  		if (epc_features->bar[bar].type == BAR_FIXED)
>  			test_reg_size = epc_features->bar[bar].fixed_size;
>  		else
> -			test_reg_size = bar_size[bar];
> +			test_reg_size = epf_test->bar_size[bar];
>  
>  		base = pci_epf_alloc_space(epf, test_reg_size, bar,
>  					   epc_features, PRIMARY_INTERFACE);
> @@ -1312,6 +1315,87 @@ static void pci_epf_test_unbind(struct pci_epf *epf)
>  	pci_epf_test_free_space(epf);
>  }
>  
> +#define PCI_EPF_TEST_BAR_SIZE_R(_name, _id)				\
> +	static ssize_t pci_epf_test_##_name##_show(struct config_item *item,	\

Drop the extra indentation at the beginning of the ligne. Many Macro defined
functions use that style.

> +						   char *page)		\
> +	{								\
> +		struct config_group *group = to_config_group(item);	\
> +		struct pci_epf_test *epf_test = container_of(group,	\
> +					struct pci_epf_test, group);	\

Splitting this line after the "=" would be nicer.

> +									\
> +		return sprintf(page, "%zu\n", epf_test->bar_size[_id]);	\

sysfs_emit() ?

> +	}
> +
> +#define PCI_EPF_TEST_BAR_SIZE_W(_name, _id)				\
> +	static ssize_t pci_epf_test_##_name##_store(struct config_item *item, \
> +						    const char *page, size_t len) \
> +	{								\
> +		struct config_group *group = to_config_group(item);	\
> +		struct pci_epf_test *epf_test = container_of(group,	\
> +					struct pci_epf_test, group);	\
> +		int val;						\
> +		int ret;						\
> +									\
> +		ret = kstrtouint(page, 0, &val);			\
> +		if (ret)						\
> +			return ret;					\
> +									\
> +		if (!is_power_of_2(val))				\
> +			return -EINVAL;					\
> +									\
> +		epf_test->bar_size[_id] = val;				\
> +									\
> +		return len;						\
> +	}
> +
> +PCI_EPF_TEST_BAR_SIZE_R(bar0_size, BAR_0)
> +PCI_EPF_TEST_BAR_SIZE_W(bar0_size, BAR_0)
> +PCI_EPF_TEST_BAR_SIZE_R(bar1_size, BAR_1)
> +PCI_EPF_TEST_BAR_SIZE_W(bar1_size, BAR_1)
> +PCI_EPF_TEST_BAR_SIZE_R(bar2_size, BAR_2)
> +PCI_EPF_TEST_BAR_SIZE_W(bar2_size, BAR_2)
> +PCI_EPF_TEST_BAR_SIZE_R(bar3_size, BAR_3)
> +PCI_EPF_TEST_BAR_SIZE_W(bar3_size, BAR_3)
> +PCI_EPF_TEST_BAR_SIZE_R(bar4_size, BAR_4)
> +PCI_EPF_TEST_BAR_SIZE_W(bar4_size, BAR_4)
> +PCI_EPF_TEST_BAR_SIZE_R(bar5_size, BAR_5)
> +PCI_EPF_TEST_BAR_SIZE_W(bar5_size, BAR_5)
> +
> +CONFIGFS_ATTR(pci_epf_test_, bar0_size);
> +CONFIGFS_ATTR(pci_epf_test_, bar1_size);
> +CONFIGFS_ATTR(pci_epf_test_, bar2_size);
> +CONFIGFS_ATTR(pci_epf_test_, bar3_size);
> +CONFIGFS_ATTR(pci_epf_test_, bar4_size);
> +CONFIGFS_ATTR(pci_epf_test_, bar5_size);
> +
> +static struct configfs_attribute *pci_epf_test_attrs[] = {
> +	&pci_epf_test_attr_bar0_size,
> +	&pci_epf_test_attr_bar1_size,
> +	&pci_epf_test_attr_bar2_size,
> +	&pci_epf_test_attr_bar3_size,
> +	&pci_epf_test_attr_bar4_size,
> +	&pci_epf_test_attr_bar5_size,
> +	NULL,
> +};
> +
> +static const struct config_item_type pci_epf_test_group_type = {
> +	.ct_attrs	= pci_epf_test_attrs,
> +	.ct_owner	= THIS_MODULE,
> +};
> +
> +static struct config_group *pci_epf_test_add_cfs(struct pci_epf *epf,
> +						 struct config_group *group)
> +{
> +	struct pci_epf_test *epf_test = epf_get_drvdata(epf);
> +	struct config_group *epf_group = &epf_test->group;
> +	struct device *dev = &epf->dev;
> +
> +	config_group_init_type_name(epf_group, dev_name(dev),
> +				    &pci_epf_test_group_type);
> +
> +	return epf_group;
> +}
> +
>  static const struct pci_epf_device_id pci_epf_test_ids[] = {
>  	{
>  		.name = "pci_epf_test",
> @@ -1324,6 +1408,7 @@ static int pci_epf_test_probe(struct pci_epf *epf,
>  {
>  	struct pci_epf_test *epf_test;
>  	struct device *dev = &epf->dev;
> +	enum pci_barno bar;
>  
>  	epf_test = devm_kzalloc(dev, sizeof(*epf_test), GFP_KERNEL);
>  	if (!epf_test)
> @@ -1331,6 +1416,8 @@ static int pci_epf_test_probe(struct pci_epf *epf,
>  
>  	epf->header = &test_header;
>  	epf_test->epf = epf;
> +	for (bar = BAR_0; bar < PCI_STD_NUM_BARS; bar++)
> +		epf_test->bar_size[bar] = default_bar_size[bar];
>  
>  	INIT_DELAYED_WORK(&epf_test->cmd_handler, pci_epf_test_cmd_handler);
>  
> @@ -1343,6 +1430,7 @@ static int pci_epf_test_probe(struct pci_epf *epf,
>  static const struct pci_epf_ops ops = {
>  	.unbind	= pci_epf_test_unbind,
>  	.bind	= pci_epf_test_bind,
> +	.add_cfs = pci_epf_test_add_cfs,
>  };
>  
>  static struct pci_epf_driver test_driver = {
> 
> base-commit: 0ebf8e7943e01b2c38c199228f51adbb89c02425


-- 
Damien Le Moal
Western Digital Research