On 1/10/24 4:40 PM, Ethan Zhao wrote:
On 1/10/2024 1:28 PM, Baolu Lu wrote:
On 12/29/23 1:05 AM, Ethan Zhao wrote:
When the ATS Invalidation request timeout happens, the qi_submit_sync()
will restart and loop for the invalidation request forever till it is
done, it will block another Invalidation thread such as the fq_timer
to issue invalidation request, cause the system lockup as following
[exception RIP: native_queued_spin_lock_slowpath+92]
RIP: ffffffffa9d1025c RSP: ffffb202f268cdc8 RFLAGS: 00000002
RAX: 0000000000000101 RBX: ffffffffab36c2a0 RCX: 0000000000000000
RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffffffffab36c2a0
RBP: ffffffffab36c2a0 R8: 0000000000000001 R9: 0000000000000000
R10: 0000000000000010 R11: 0000000000000018 R12: 0000000000000000
R13: 0000000000000004 R14: ffff9e10d71b1c88 R15: ffff9e10d71b1980
ORIG_RAX: ffffffffffffffff CS: 0010 SS: 0018
(the left part of exception see the hotplug case of ATS capable device)
If one endpoint device just no response to the ATS Invalidation request,
but is not gone, it will bring down the whole system, to avoid such
case, don't try the timeout ATS Invalidation request forever.
Signed-off-by: Ethan Zhao <haifeng.zhao@xxxxxxxxxxxxxxx>
---
drivers/iommu/intel/dmar.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/iommu/intel/dmar.c b/drivers/iommu/intel/dmar.c
index 0a8d628a42ee..9edb4b44afca 100644
--- a/drivers/iommu/intel/dmar.c
+++ b/drivers/iommu/intel/dmar.c
@@ -1453,7 +1453,7 @@ int qi_submit_sync(struct intel_iommu *iommu,
struct qi_desc *desc,
reclaim_free_desc(qi);
raw_spin_unlock_irqrestore(&qi->q_lock, flags);
- if (rc == -EAGAIN)
+ if (rc == -EAGAIN && type !=QI_DIOTLB_TYPE && type !=
QI_DEIOTLB_TYPE)
goto restart;
if (iotlb_start_ktime)
Above is also unnecessary if qi_check_fault() returns -ETIMEDOUT,
instead of -EAGAIN. Or did I miss anything?
It is pro if we fold it into qi_check_fault(), the con is we have to add
more parameter to qi_check_fault(), no need check invalidation type
of QI_DIOTLB_TYPE&QI_DEIOTLB_TYPE in qi_check_fault() ?
No need to check the request type as multiple requests might be batched
together in a single call. This is also the reason why I asked you to
add a flag bit to this helper and make the intention explicit, say,
"This includes requests to interact with a PCI endpoint. The device may
become unavailable at any time, so do not attempt to retry if ITE is
detected and the device has gone away."
Best regards,
baolu
