Re: [PATCH 1/1] iommu/vt-d: Fix lockdep splat in iommu_flush_dev_iotlb()

2020-10-01 Thread Joerg Roedel
On Sun, Sep 27, 2020 at 02:24:28PM +0800, Lu Baolu wrote:
>  drivers/iommu/intel/iommu.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)

Applied for v5.9, thanks.
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[PATCH 1/1] iommu/vt-d: Fix lockdep splat in iommu_flush_dev_iotlb()

2020-09-27 Thread Lu Baolu
Lock(>lock) without disabling irq causes lockdep warnings.

[   12.703950] 
[   12.703962] WARNING: possible irq lock inversion dependency detected
[   12.703975] 5.9.0-rc6+ #659 Not tainted
[   12.703983] 
[   12.703995] systemd-udevd/284 just changed the state of lock:
[   12.704007] bd6ff4d8 (device_domain_lock){..-.}-{2:2}, at:
   iommu_flush_dev_iotlb.part.57+0x2e/0x90
[   12.704031] but this lock took another, SOFTIRQ-unsafe lock in the past:
[   12.704043]  (>lock){+.+.}-{2:2}
[   12.704045]

   and interrupts could create inverse lock ordering between
   them.

[   12.704073]
   other info that might help us debug this:
[   12.704085]  Possible interrupt unsafe locking scenario:

[   12.704097]CPU0CPU1
[   12.704106]
[   12.704115]   lock(>lock);
[   12.704123]local_irq_disable();
[   12.704134]lock(device_domain_lock);
[   12.704146]lock(>lock);
[   12.704158]   
[   12.704164] lock(device_domain_lock);
[   12.704174]
*** DEADLOCK ***

Signed-off-by: Lu Baolu 
---
 drivers/iommu/intel/iommu.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c
index 1b7d390beb68..722545f61ba2 100644
--- a/drivers/iommu/intel/iommu.c
+++ b/drivers/iommu/intel/iommu.c
@@ -2699,7 +2699,7 @@ static struct dmar_domain 
*dmar_insert_one_dev_info(struct intel_iommu *iommu,
}
 
/* Setup the PASID entry for requests without PASID: */
-   spin_lock(>lock);
+   spin_lock_irqsave(>lock, flags);
if (hw_pass_through && domain_type_is_si(domain))
ret = intel_pasid_setup_pass_through(iommu, domain,
dev, PASID_RID2PASID);
@@ -2709,7 +2709,7 @@ static struct dmar_domain 
*dmar_insert_one_dev_info(struct intel_iommu *iommu,
else
ret = intel_pasid_setup_second_level(iommu, domain,
dev, PASID_RID2PASID);
-   spin_unlock(>lock);
+   spin_unlock_irqrestore(>lock, flags);
if (ret) {
dev_err(dev, "Setup RID2PASID failed\n");
dmar_remove_one_dev_info(dev);
-- 
2.17.1

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