cxl: Check periodically the coherent platform function's state
In the PowerVM environment, the PHYP CoherentAccel component manages
the state of the Coherent Accelerator Processor Interface adapter and
virtualizes CAPI resources, handles CAPP, PSL, PSL Slice errors - and
interrupts - and provides a new set of hcalls for the OS APIs to utilize
Accelerator Function Unit (AFU).
During the course of operation, a coherent platform function can
encounter errors. Some possible reason for errors are:
• Hardware recoverable and unrecoverable errors
• Transient and over-threshold correctable errors
PHYP implements its own state model for the coherent platform function.
The state of the AFU is available through a hcall.
The current implementation of the cxl driver, for the PowerVM
environment, checks this state of the AFU only when an action is
requested - open a device, ioctl command, memory map, attach/detach a
process - from an external driver - cxlflash, libcxl. If an error is
detected the cxl driver handles the error according the content of the
Power Architecture Platform Requirements document.
But in case of low-level troubles (or error injection), the PHYP
component may reset the card and change the AFU state. The PHYP
interface doesn't provide any way to be notified when that happens thus
implies that the cxl driver:
• cannot handle immediatly the state change of the AFU.
• cannot notify other drivers (cxlflash, ...)
The purpose of this patch is to wake up the cpu periodically to check
the current state of each AFU and to see if we need to enter an error
recovery path.
Signed-off-by: Christophe Lombard <clombard@linux.vnet.ibm.com>
Acked-by: Ian Munsie <imunsie@au1.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
diff --git a/drivers/misc/cxl/guest.c b/drivers/misc/cxl/guest.c
index c2815b9..bc8d0b9 100644
--- a/drivers/misc/cxl/guest.c
+++ b/drivers/misc/cxl/guest.c
@@ -178,6 +178,9 @@
u64 state;
int rc = 0;
+ if (!afu)
+ return -EIO;
+
rc = cxl_h_read_error_state(afu->guest->handle, &state);
if (!rc) {
WARN_ON(state != H_STATE_NORMAL &&
@@ -833,7 +836,6 @@
switch (cur_state) {
case H_STATE_NORMAL:
afu->guest->previous_state = cur_state;
- rc = 1;
break;
case H_STATE_DISABLE:
@@ -849,7 +851,6 @@
pci_error_handlers(afu, CXL_SLOT_RESET_EVENT,
pci_channel_io_normal);
pci_error_handlers(afu, CXL_RESUME_EVENT, 0);
- rc = 1;
}
afu->guest->previous_state = 0;
break;
@@ -874,39 +875,30 @@
return rc;
}
-static int afu_do_recovery(struct cxl_afu *afu)
+static void afu_handle_errstate(struct work_struct *work)
{
- int rc;
+ struct cxl_afu_guest *afu_guest =
+ container_of(to_delayed_work(work), struct cxl_afu_guest, work_err);
- /* many threads can arrive here, in case of detach_all for example.
- * Only one needs to drive the recovery
- */
- if (mutex_trylock(&afu->guest->recovery_lock)) {
- rc = afu_update_state(afu);
- mutex_unlock(&afu->guest->recovery_lock);
- return rc;
- }
- return 0;
+ if (!afu_update_state(afu_guest->parent) &&
+ afu_guest->previous_state == H_STATE_PERM_UNAVAILABLE)
+ return;
+
+ if (afu_guest->handle_err == true)
+ schedule_delayed_work(&afu_guest->work_err,
+ msecs_to_jiffies(3000));
}
static bool guest_link_ok(struct cxl *cxl, struct cxl_afu *afu)
{
int state;
- if (afu) {
- if (afu_read_error_state(afu, &state) ||
- state != H_STATE_NORMAL) {
- if (afu_do_recovery(afu) > 0) {
- /* check again in case we've just fixed it */
- if (!afu_read_error_state(afu, &state) &&
- state == H_STATE_NORMAL)
- return true;
- }
- return false;
- }
+ if (afu && (!afu_read_error_state(afu, &state))) {
+ if (state == H_STATE_NORMAL)
+ return true;
}
- return true;
+ return false;
}
static int afu_properties_look_ok(struct cxl_afu *afu)
@@ -944,8 +936,6 @@
return -ENOMEM;
}
- mutex_init(&afu->guest->recovery_lock);
-
if ((rc = dev_set_name(&afu->dev, "afu%i.%i",
adapter->adapter_num,
slice)))
@@ -1001,6 +991,15 @@
afu->enabled = true;
+ /*
+ * wake up the cpu periodically to check the state
+ * of the AFU using "afu" stored in the guest structure.
+ */
+ afu->guest->parent = afu;
+ afu->guest->handle_err = true;
+ INIT_DELAYED_WORK(&afu->guest->work_err, afu_handle_errstate);
+ schedule_delayed_work(&afu->guest->work_err, msecs_to_jiffies(1000));
+
if ((rc = cxl_pci_vphb_add(afu)))
dev_info(&afu->dev, "Can't register vPHB\n");
@@ -1029,6 +1028,10 @@
if (!afu)
return;
+ /* flush and stop pending job */
+ afu->guest->handle_err = false;
+ flush_delayed_work(&afu->guest->work_err);
+
cxl_pci_vphb_remove(afu);
cxl_sysfs_afu_remove(afu);