[PATCH v5 10/11] cxl: EEH support
Daniel Axtens
dja at axtens.net
Fri Aug 14 17:41:26 AEST 2015
EEH (Enhanced Error Handling) allows a driver to recover from the
temporary failure of an attached PCI card. Enable basic CXL support
for EEH.
Signed-off-by: Daniel Axtens <dja at axtens.net>
---
drivers/misc/cxl/cxl.h | 1 +
drivers/misc/cxl/pci.c | 253 ++++++++++++++++++++++++++++++++++++++++++++++++
drivers/misc/cxl/vphb.c | 8 ++
3 files changed, 262 insertions(+)
diff --git a/drivers/misc/cxl/cxl.h b/drivers/misc/cxl/cxl.h
index cda02412b01e..6f5386653dae 100644
--- a/drivers/misc/cxl/cxl.h
+++ b/drivers/misc/cxl/cxl.h
@@ -726,6 +726,7 @@ int cxl_psl_purge(struct cxl_afu *afu);
void cxl_stop_trace(struct cxl *cxl);
int cxl_pci_vphb_add(struct cxl_afu *afu);
+void cxl_pci_vphb_reconfigure(struct cxl_afu *afu);
void cxl_pci_vphb_remove(struct cxl_afu *afu);
extern struct pci_driver cxl_pci_driver;
diff --git a/drivers/misc/cxl/pci.c b/drivers/misc/cxl/pci.c
index bfbd6478c0c5..03ddb2d8f974 100644
--- a/drivers/misc/cxl/pci.c
+++ b/drivers/misc/cxl/pci.c
@@ -24,6 +24,7 @@
#include <asm/io.h>
#include "cxl.h"
+#include <misc/cxl.h>
#define CXL_PCI_VSEC_ID 0x1280
@@ -1252,10 +1253,262 @@ static void cxl_remove(struct pci_dev *dev)
cxl_remove_adapter(adapter);
}
+static pci_ers_result_t cxl_vphb_error_detected(struct cxl_afu *afu,
+ pci_channel_state_t state)
+{
+ struct pci_dev *afu_dev;
+ pci_ers_result_t result = PCI_ERS_RESULT_NEED_RESET;
+ pci_ers_result_t afu_result = PCI_ERS_RESULT_NEED_RESET;
+
+ /* There should only be one entry, but go through the list
+ * anyway
+ */
+ list_for_each_entry(afu_dev, &afu->phb->bus->devices, bus_list) {
+ if (!afu_dev->driver)
+ continue;
+
+ afu_dev->error_state = state;
+
+ if (afu_dev->driver->err_handler)
+ afu_result = afu_dev->driver->err_handler->error_detected(afu_dev,
+ state);
+ /* Disconnect trumps all, NONE trumps NEED_RESET */
+ if (afu_result == PCI_ERS_RESULT_DISCONNECT)
+ result = PCI_ERS_RESULT_DISCONNECT;
+ else if ((afu_result == PCI_ERS_RESULT_NONE) &&
+ (result == PCI_ERS_RESULT_NEED_RESET))
+ result = PCI_ERS_RESULT_NONE;
+ }
+ return result;
+}
+
+static pci_ers_result_t cxl_pci_error_detected(struct pci_dev *pdev,
+ pci_channel_state_t state)
+{
+ struct cxl *adapter = pci_get_drvdata(pdev);
+ struct cxl_afu *afu;
+ pci_ers_result_t result = PCI_ERS_RESULT_NEED_RESET;
+ int i;
+
+ /* At this point, we could still have an interrupt pending.
+ * Let's try to get them out of the way before they do
+ * anything we don't like.
+ */
+ schedule();
+
+ /* If we're permanently dead, give up. */
+ if (state == pci_channel_io_perm_failure) {
+ /* Tell the AFU drivers; but we don't care what they
+ * say, we're going away.
+ */
+ for (i = 0; i < adapter->slices; i++) {
+ afu = adapter->afu[i];
+ cxl_vphb_error_detected(afu, state);
+ }
+ return PCI_ERS_RESULT_DISCONNECT;
+ }
+
+ /* Are we reflashing?
+ *
+ * If we reflash, we could come back as something entirely
+ * different, including a non-CAPI card. As such, by default
+ * we don't participate in the process. We'll be unbound and
+ * the slot re-probed. (TODO: check EEH doesn't blindly rebind
+ * us!)
+ *
+ * However, this isn't the entire story: for reliablity
+ * reasons, we usually want to reflash the FPGA on PERST in
+ * order to get back to a more reliable known-good state.
+ *
+ * This causes us a bit of a problem: if we reflash we can't
+ * trust that we'll come back the same - we could have a new
+ * image and been PERSTed in order to load that
+ * image. However, most of the time we actually *will* come
+ * back the same - for example a regular EEH event.
+ *
+ * Therefore, we allow the user to assert that the image is
+ * indeed the same and that we should continue on into EEH
+ * anyway.
+ */
+ if (adapter->perst_loads_image && !adapter->perst_same_image) {
+ /* TODO take the PHB out of CXL mode */
+ dev_info(&pdev->dev, "reflashing, so opting out of EEH!\n");
+ return PCI_ERS_RESULT_NONE;
+ }
+
+ /*
+ * At this point, we want to try to recover. We'll always
+ * need a complete slot reset: we don't trust any other reset.
+ *
+ * Now, we go through each AFU:
+ * - We send the driver, if bound, an error_detected callback.
+ * We expect it to clean up, but it can also tell us to give
+ * up and permanently detach the card. To simplify things, if
+ * any bound AFU driver doesn't support EEH, we give up on EEH.
+ *
+ * - We detach all contexts associated with the AFU. This
+ * does not free them, but puts them into a CLOSED state
+ * which causes any the associated files to return useful
+ * errors to userland. It also unmaps, but does not free,
+ * any IRQs.
+ *
+ * - We clean up our side: releasing and unmapping resources we hold
+ * so we can wire them up again when the hardware comes back up.
+ *
+ * Driver authors should note:
+ *
+ * - Any contexts you create in your kernel driver (except
+ * those associated with anonymous file descriptors) are
+ * your responsibility to free and recreate. Likewise with
+ * any attached resources.
+ *
+ * - We will take responsibility for re-initialising the
+ * device context (the one set up for you in
+ * cxl_pci_enable_device_hook and accessed through
+ * cxl_get_context). If you've attached IRQs or other
+ * resources to it, they remains yours to free.
+ *
+ * You can call the same functions to release resources as you
+ * normally would: we make sure that these functions continue
+ * to work when the hardware is down.
+ *
+ * Two examples:
+ *
+ * 1) If you normally free all your resources at the end of
+ * each request, or if you use anonymous FDs, your
+ * error_detected callback can simply set a flag to tell
+ * your driver not to start any new calls. You can then
+ * clear the flag in the resume callback.
+ *
+ * 2) If you normally allocate your resources on startup:
+ * * Set a flag in error_detected as above.
+ * * Let CXL detach your contexts.
+ * * In slot_reset, free the old resources and allocate new ones.
+ * * In resume, clear the flag to allow things to start.
+ */
+ for (i = 0; i < adapter->slices; i++) {
+ afu = adapter->afu[i];
+
+ result = cxl_vphb_error_detected(afu, state);
+
+ /* Only continue if everyone agrees on NEED_RESET */
+ if (result != PCI_ERS_RESULT_NEED_RESET)
+ return result;
+
+ cxl_context_detach_all(afu);
+ cxl_afu_deactivate_mode(afu);
+ cxl_deconfigure_afu(afu);
+ }
+ cxl_deconfigure_adapter(adapter);
+
+ return result;
+}
+
+static pci_ers_result_t cxl_pci_slot_reset(struct pci_dev *pdev)
+{
+ struct cxl *adapter = pci_get_drvdata(pdev);
+ struct cxl_afu *afu;
+ struct cxl_context *ctx;
+ struct pci_dev *afu_dev;
+ pci_ers_result_t afu_result = PCI_ERS_RESULT_RECOVERED;
+ pci_ers_result_t result = PCI_ERS_RESULT_RECOVERED;
+ int i;
+
+ if (cxl_configure_adapter(adapter, pdev))
+ goto err;
+
+ for (i = 0; i < adapter->slices; i++) {
+ afu = adapter->afu[i];
+
+ if (cxl_configure_afu(afu, adapter, pdev))
+ goto err;
+
+ if (cxl_afu_select_best_mode(afu))
+ goto err;
+
+ cxl_pci_vphb_reconfigure(afu);
+
+ list_for_each_entry(afu_dev, &afu->phb->bus->devices, bus_list) {
+ /* Reset the device context.
+ * TODO: make this less disruptive
+ */
+ ctx = cxl_get_context(afu_dev);
+
+ if (ctx && cxl_release_context(ctx))
+ goto err;
+
+ ctx = cxl_dev_context_init(afu_dev);
+ if (!ctx)
+ goto err;
+
+ afu_dev->dev.archdata.cxl_ctx = ctx;
+
+ if (cxl_afu_check_and_enable(afu))
+ goto err;
+
+ afu_dev->error_state = pci_channel_io_normal;
+
+ /* If there's a driver attached, allow it to
+ * chime in on recovery. Drivers should check
+ * if everything has come back OK, but
+ * shouldn't start new work until we call
+ * their resume function.
+ */
+ if (!afu_dev->driver)
+ continue;
+
+ if (afu_dev->driver->err_handler &&
+ afu_dev->driver->err_handler->slot_reset)
+ afu_result = afu_dev->driver->err_handler->slot_reset(afu_dev);
+
+ if (afu_result == PCI_ERS_RESULT_DISCONNECT)
+ result = PCI_ERS_RESULT_DISCONNECT;
+ }
+ }
+ return result;
+
+err:
+ /* All the bits that happen in both error_detected and cxl_remove
+ * should be idempotent, so we don't need to worry about leaving a mix
+ * of unconfigured and reconfigured resources.
+ */
+ dev_err(&pdev->dev, "EEH recovery failed. Asking to be disconnected.\n");
+ return PCI_ERS_RESULT_DISCONNECT;
+}
+
+static void cxl_pci_resume(struct pci_dev *pdev)
+{
+ struct cxl *adapter = pci_get_drvdata(pdev);
+ struct cxl_afu *afu;
+ struct pci_dev *afu_dev;
+ int i;
+
+ /* Everything is back now. Drivers should restart work now.
+ * This is not the place to be checking if everything came back up
+ * properly, because there's no return value: do that in slot_reset.
+ */
+ for (i = 0; i < adapter->slices; i++) {
+ afu = adapter->afu[i];
+
+ list_for_each_entry(afu_dev, &afu->phb->bus->devices, bus_list) {
+ if (afu_dev->driver && afu_dev->driver->err_handler &&
+ afu_dev->driver->err_handler->resume)
+ afu_dev->driver->err_handler->resume(afu_dev);
+ }
+ }
+}
+
+static const struct pci_error_handlers cxl_err_handler = {
+ .error_detected = cxl_pci_error_detected,
+ .slot_reset = cxl_pci_slot_reset,
+ .resume = cxl_pci_resume,
+};
+
struct pci_driver cxl_pci_driver = {
.name = "cxl-pci",
.id_table = cxl_pci_tbl,
.probe = cxl_probe,
.remove = cxl_remove,
.shutdown = cxl_remove,
+ .err_handler = &cxl_err_handler,
};
diff --git a/drivers/misc/cxl/vphb.c b/drivers/misc/cxl/vphb.c
index 2930911c1e42..6dd16a6d153f 100644
--- a/drivers/misc/cxl/vphb.c
+++ b/drivers/misc/cxl/vphb.c
@@ -266,6 +266,14 @@ int cxl_pci_vphb_add(struct cxl_afu *afu)
return 0;
}
+void cxl_pci_vphb_reconfigure(struct cxl_afu *afu)
+{
+ /* When we are reconfigured, the AFU's MMIO space is unmapped
+ * and remapped. We need to reflect this in the PHB's view of
+ * the world.
+ */
+ afu->phb->cfg_addr = afu->afu_desc_mmio + afu->crs_offset;
+}
void cxl_pci_vphb_remove(struct cxl_afu *afu)
{
--
2.1.4
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