[PATCH v4] PCI: endpoint: pci-epf-test: Allow overriding default BAR sizes

[PATCH v4] 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 V3:
-Use sysfs_emit() (Damien)
-Reduce indendation level of macros by one tab (Damien)

 Documentation/PCI/endpoint/pci-test-howto.rst |  19 ++++
 drivers/pci/endpoint/functions/pci-epf-test.c | 100 +++++++++++++++++-
 2 files changed, 117 insertions(+), 2 deletions(-)

diff --git a/Documentation/PCI/endpoint/pci-test-howto.rst b/Documentation/PCI/endpoint/pci-test-howto.rst
index dd66858cde46..cf38daa512ea 100644
--- a/Documentation/PCI/endpoint/pci-test-howto.rst
+++ b/Documentation/PCI/endpoint/pci-test-howto.rst
@@ -84,6 +84,25 @@ 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
+
+Overriding the default BAR sizes can only be done before binding the
+pci-epf-test device to a PCI endpoint controller driver.
+
+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..f30f6bddda28 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 +1315,95 @@ 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 sysfs_emit(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;							\
+									\
+	/*								\
+	 * BAR sizes can only be modified before binding to an EPC,	\
+	 * pci_epf_test_alloc_space() is called in .bind().		\
+	 */								\
+	if (epf_test->epf->epc)						\
+		return -EINVAL;						\
+									\
+	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 +1416,7 @@ 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 +1424,8 @@ 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 +1438,7 @@ 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 v4] PCI: endpoint: pci-epf-test: Allow overriding default BAR sizes

[Niklas Cassel]

On Thu, Jan 29, 2026 at 02:23:25PM +0100, Niklas Cassel wrote:
> +#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;							\
> +									\
> +	/*								\
> +	 * BAR sizes can only be modified before binding to an EPC,	\
> +	 * pci_epf_test_alloc_space() is called in .bind().		\

Argh...

This comment was supposed to be:
... EPC,
as pci_epf_test_alloc_space() is called in .bind().

(I forgot to readd the word "as" when rewrapping the comment...)

Mani, if no other comments, perhaps you could fixup while applying?

(Sorry for the trouble...)


Kind regards,
Niklas


> +	 */								\
> +	if (epf_test->epf->epc)						\
> +		return -EINVAL;						\
> +									\
> +	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;							\
> +}

Re: [PATCH v4] PCI: endpoint: pci-epf-test: Allow overriding default BAR sizes

[Damien Le Moal]

On 1/29/26 22:23, 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>

Looks OK to me.

Reviewed-by: Damien Le Moal <dlemoal@kernel.org>

One nit below.


> +#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;							\

You can use one line to declare both variables.

> +									\
> +	/*								\
> +	 * BAR sizes can only be modified before binding to an EPC,	\
> +	 * pci_epf_test_alloc_space() is called in .bind().		\
> +	 */								\
> +	if (epf_test->epf->epc)						\
> +		return -EINVAL;						\
> +									\
> +	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;							\
> +}


-- 
Damien Le Moal
Western Digital Research