Commit 9e8df8a2 authored by Daniel Axtens's avatar Daniel Axtens Committed by Michael Ellerman

cxl: EEH support

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: 's avatarDaniel Axtens <dja@axtens.net>
Signed-off-by: 's avatarMichael Ellerman <mpe@ellerman.id.au>
parent 13e68d8b
......@@ -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;
......
......@@ -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,
};
......@@ -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)
{
......
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