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: Daniel Axtens <dja@axtens.net>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
This commit is contained in:
Daniel Axtens 2015-08-14 17:41:25 +10:00 committed by Michael Ellerman
parent 4e1efb403c
commit 13e68d8bd0
6 changed files with 61 additions and 0 deletions

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@ -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

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@ -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);

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@ -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);

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@ -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) {

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@ -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),
};

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@ -200,4 +200,14 @@ unsigned int cxl_fd_poll(struct file *file, struct poll_table_struct *poll);
ssize_t cxl_fd_read(struct file *file, char __user *buf, size_t count,
loff_t *off);
/*
* For EEH, a driver may want to assert a PERST will reload the same image
* from flash into the FPGA.
*
* This is a property of the entire adapter, not a single AFU, so drivers
* should set this property with care!
*/
void cxl_perst_reloads_same_image(struct cxl_afu *afu,
bool perst_reloads_same_image);
#endif /* _MISC_CXL_H */