From 13e68d8bd05c998cae452a4f3400af1e8edd852e Mon Sep 17 00:00:00 2001 From: Daniel Axtens Date: Fri, 14 Aug 2015 17:41:25 +1000 Subject: [PATCH] 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 Signed-off-by: Michael Ellerman --- Documentation/ABI/testing/sysfs-class-cxl | 10 ++++++++++ drivers/misc/cxl/api.c | 7 +++++++ drivers/misc/cxl/cxl.h | 1 + drivers/misc/cxl/pci.c | 7 +++++++ drivers/misc/cxl/sysfs.c | 26 ++++++++++++++++++++++++++ include/misc/cxl.h | 10 ++++++++++ 6 files changed, 61 insertions(+) diff --git a/Documentation/ABI/testing/sysfs-class-cxl b/Documentation/ABI/testing/sysfs-class-cxl index acfe9df..b07e86d 100644 --- a/Documentation/ABI/testing/sysfs-class-cxl +++ b/Documentation/ABI/testing/sysfs-class-cxl @@ -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//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 diff --git a/drivers/misc/cxl/api.c b/drivers/misc/cxl/api.c index 729e085..6a768a9 100644 --- a/drivers/misc/cxl/api.c +++ b/drivers/misc/cxl/api.c @@ -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); diff --git a/drivers/misc/cxl/cxl.h b/drivers/misc/cxl/cxl.h index d540542..cda0241 100644 --- a/drivers/misc/cxl/cxl.h +++ b/drivers/misc/cxl/cxl.h @@ -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); diff --git a/drivers/misc/cxl/pci.c b/drivers/misc/cxl/pci.c index 2b61cb1..bfbd647 100644 --- a/drivers/misc/cxl/pci.c +++ b/drivers/misc/cxl/pci.c @@ -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) { diff --git a/drivers/misc/cxl/sysfs.c b/drivers/misc/cxl/sysfs.c index 31f38bc..6619cf1 100644 --- a/drivers/misc/cxl/sysfs.c +++ b/drivers/misc/cxl/sysfs.c @@ -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), }; diff --git a/include/misc/cxl.h b/include/misc/cxl.h index 7a6c1d6..f2ffe5b 100644 --- a/include/misc/cxl.h +++ b/include/misc/cxl.h @@ -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 */ -- 2.7.4