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PCI/ERR: Handle fatal error recovery

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We don't need to be paranoid about the topology changing while handling an
error.  If the device has changed in a hotplug capable slot, we can rely on
the presence detection handling to react to a changing topology.

Restore the fatal error handling behavior that existed before merging DPC
with AER with 7e9084b367 ("PCI/AER: Handle ERR_FATAL with removal and
re-enumeration of devices").

Signed-off-by: Keith Busch <keith.busch@intel.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Sinan Kaya <okaya@kernel.org>
This commit is contained in:
Keith Busch
2018-09-20 10:27:12 -06:00
committed by Bjorn Helgaas
parent c4eed62a21
commit bdb5ac8577
5 changed files with 28 additions and 102 deletions
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35
Documentation/PCI/pci-error-recovery.txt
View File

@@ -110,7 +110,7 @@ The actual steps taken by a platform to recover from a PCI error
event will be platform-dependent, but will follow the general
sequence described below.
STEP 0: Error Event: ERR_NONFATAL
STEP 0: Error Event
-------------------
A PCI bus error is detected by the PCI hardware. On powerpc, the slot
is isolated, in that all I/O is blocked: all reads return 0xffffffff,
@@ -228,7 +228,13 @@ proceeds to either STEP3 (Link Reset) or to STEP 5 (Resume Operations).
If any driver returned PCI_ERS_RESULT_NEED_RESET, then the platform
proceeds to STEP 4 (Slot Reset)
STEP 3: Slot Reset
STEP 3: Link Reset
------------------
The platform resets the link. This is a PCI-Express specific step
and is done whenever a fatal error has been detected that can be
"solved" by resetting the link.
STEP 4: Slot Reset
------------------
In response to a return value of PCI_ERS_RESULT_NEED_RESET, the
@@ -314,7 +320,7 @@ Failure).
>>> However, it probably should.
STEP 4: Resume Operations
STEP 5: Resume Operations
-------------------------
The platform will call the resume() callback on all affected device
drivers if all drivers on the segment have returned
@@ -326,7 +332,7 @@ a result code.
At this point, if a new error happens, the platform will restart
a new error recovery sequence.
STEP 5: Permanent Failure
STEP 6: Permanent Failure
-------------------------
A "permanent failure" has occurred, and the platform cannot recover
the device. The platform will call error_detected() with a
@@ -349,27 +355,6 @@ errors. See the discussion in powerpc/eeh-pci-error-recovery.txt
for additional detail on real-life experience of the causes of
software errors.
STEP 0: Error Event: ERR_FATAL
-------------------
PCI bus error is detected by the PCI hardware. On powerpc, the slot is
isolated, in that all I/O is blocked: all reads return 0xffffffff, all
writes are ignored.
STEP 1: Remove devices
--------------------
Platform removes the devices depending on the error agent, it could be
this port for all subordinates or upstream component (likely downstream
port)
STEP 2: Reset link
--------------------
The platform resets the link. This is a PCI-Express specific step and is
done whenever a fatal error has been detected that can be "solved" by
resetting the link.
STEP 3: Re-enumerate the devices
--------------------
Initiates the re-enumeration.
Conclusion; General Remarks
---------------------------