From: Joerg Roedel <jroedel@xxxxxxx>
The use of the SR-IOV lock for ATS causes a dead-lock in the
AMD-IOMMU driver when virtual functions are added that have
an ATS capability.
The problem is that the VFs will be added to the bus with
the SR-IOV lock held. While added to the bus the
device-notifiers will run and invoke AMD IOMMU code, which
itself will assign the device to a domain try to enable ATS.
When it calls pci_enable_ats() this will dead-lock.
Fix this by introducing a global ats_lock. ATS enablement
and disablement isn't in any fast-path, so a global lock
shouldn't hurt here.
Cc: stable@xxxxxxxxxx
Reported-by: Gregor Dick <gdick@xxxxxxxxxxxxxx>
Signed-off-by: Joerg Roedel <jroedel@xxxxxxx>
---
drivers/pci/ats.c | 10 ++++++----
1 file changed, 6 insertions(+), 4 deletions(-)
diff --git a/drivers/pci/ats.c b/drivers/pci/ats.c
index a8099d4..f0c3c6f 100644
--- a/drivers/pci/ats.c
+++ b/drivers/pci/ats.c
@@ -17,6 +17,8 @@
#include "pci.h"
+static DEFINE_MUTEX(ats_lock);
+
static int ats_alloc_one(struct pci_dev *dev, int ps)
{
int pos;
@@ -67,7 +69,7 @@ int pci_enable_ats(struct pci_dev *dev, int ps)
if (dev->is_physfn || dev->is_virtfn) {
struct pci_dev *pdev = dev->is_physfn ? dev : dev->physfn;
- mutex_lock(&pdev->sriov->lock);
+ mutex_lock(&ats_lock);
if (pdev->ats)
rc = pdev->ats->stu == ps ? 0 : -EINVAL;
else
@@ -75,7 +77,7 @@ int pci_enable_ats(struct pci_dev *dev, int ps)
if (!rc)
pdev->ats->ref_cnt++;
- mutex_unlock(&pdev->sriov->lock);
+ mutex_unlock(&ats_lock);
if (rc)
return rc;
}
@@ -116,11 +118,11 @@ void pci_disable_ats(struct pci_dev *dev)
if (dev->is_physfn || dev->is_virtfn) {
struct pci_dev *pdev = dev->is_physfn ? dev : dev->physfn;
- mutex_lock(&pdev->sriov->lock);
+ mutex_lock(&ats_lock);
pdev->ats->ref_cnt--;
if (!pdev->ats->ref_cnt)
ats_free_one(pdev);
- mutex_unlock(&pdev->sriov->lock);
+ mutex_unlock(&ats_lock);
}
if (!dev->is_physfn)
--
1.9.1
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