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Commit 13e68d8b authored by Daniel Axtens's avatar Daniel Axtens Committed by Michael Ellerman
Browse files

cxl: Allow the kernel to trust that an image won't change on PERST. 



Provide a kernel API and a sysfs entry which allow a user to specify
that when a card is PERSTed, it's image will stay the same, allowing
it to participate in EEH.

cxl_reset is used to reflash the card. In that case, we cannot safely
assert that the image will not change. Therefore, disallow cxl_reset
if the flag is set.

Signed-off-by: default avatarDaniel Axtens <dja@axtens.net>
Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
parent 4e1efb40

Documentation/ABI/testing/sysfs-class-cxl

+10 −0
Original line number Diff line number Diff line
@@ -223,3 +223,13 @@ Description: write only 
                Writing 1 will issue a PERST to card which may cause the card

                to reload the FPGA depending on load_image_on_perst.

Users:		https://github.com/ibm-capi/libcxl



What:		/sys/class/cxl/<card>/perst_reloads_same_image

Date:		July 2015

Contact:	linuxppc-dev@lists.ozlabs.org

Description:	read/write

		Trust that when an image is reloaded via PERST, it will not

		have changed.

		0 = don't trust, the image may be different (default)

		1 = trust that the image will not change.

Users:		https://github.com/ibm-capi/libcxl

drivers/misc/cxl/api.c

+7 −0
Original line number Diff line number Diff line
@@ -327,3 +327,10 @@ int cxl_afu_reset(struct cxl_context *ctx) 
	return cxl_afu_check_and_enable(afu);

}

EXPORT_SYMBOL_GPL(cxl_afu_reset);



void cxl_perst_reloads_same_image(struct cxl_afu *afu,

				  bool perst_reloads_same_image)

{

	afu->adapter->perst_same_image = perst_reloads_same_image;

}

EXPORT_SYMBOL_GPL(cxl_perst_reloads_same_image);

drivers/misc/cxl/cxl.h

+1 −0
Original line number Diff line number Diff line
@@ -493,6 +493,7 @@ struct cxl { 
	bool user_image_loaded;

	bool perst_loads_image;

	bool perst_select_user;

	bool perst_same_image;

};



int cxl_alloc_one_irq(struct cxl *adapter);

drivers/misc/cxl/pci.c

+7 −0
Original line number Diff line number Diff line
@@ -878,6 +878,12 @@ int cxl_reset(struct cxl *adapter) 
	int i;

	u32 val;



	if (adapter->perst_same_image) {

		dev_warn(&dev->dev,

			 "cxl: refusing to reset/reflash when perst_reloads_same_image is set.\n");

		return -EINVAL;

	}



	dev_info(&dev->dev, "CXL reset\n");



	/* pcie_warm_reset requests a fundamental pci reset which includes a
@@ -1151,6 +1157,7 @@ static struct cxl *cxl_init_adapter(struct pci_dev *dev) 
	 * configure/reconfigure

	 */

	adapter->perst_loads_image = true;

	adapter->perst_same_image = false;



	rc = cxl_configure_adapter(adapter, dev);

	if (rc) {

drivers/misc/cxl/sysfs.c

+26 −0
Original line number Diff line number Diff line
@@ -112,12 +112,38 @@ static ssize_t load_image_on_perst_store(struct device *device, 
	return count;

}



static ssize_t perst_reloads_same_image_show(struct device *device,

				 struct device_attribute *attr,

				 char *buf)

{

	struct cxl *adapter = to_cxl_adapter(device);



	return scnprintf(buf, PAGE_SIZE, "%i\n", adapter->perst_same_image);

}



static ssize_t perst_reloads_same_image_store(struct device *device,

				 struct device_attribute *attr,

				 const char *buf, size_t count)

{

	struct cxl *adapter = to_cxl_adapter(device);

	int rc;

	int val;



	rc = sscanf(buf, "%i", &val);

	if ((rc != 1) || !(val == 1 || val == 0))

		return -EINVAL;



	adapter->perst_same_image = (val == 1 ? true : false);

	return count;

}



static struct device_attribute adapter_attrs[] = {

	__ATTR_RO(caia_version),

	__ATTR_RO(psl_revision),

	__ATTR_RO(base_image),

	__ATTR_RO(image_loaded),

	__ATTR_RW(load_image_on_perst),

	__ATTR_RW(perst_reloads_same_image),

	__ATTR(reset, S_IWUSR, NULL, reset_adapter_store),

};