From edc90fee916b4f0d14af9c6b5c08666747488ef8 Mon Sep 17 00:00:00 2001 From: Bjorn Helgaas Date: Fri, 17 Jul 2015 15:05:46 -0500 Subject: PCI: Allocate ATS struct during enumeration Previously, we allocated pci_ats structures when an IOMMU driver called pci_enable_ats(). An SR-IOV VF shares the STU setting with its PF, so when enabling ATS on the VF, we allocated a pci_ats struct for the PF if it didn't already have one. We held the sriov->lock to serialize threads concurrently enabling ATS on several VFS so only one would allocate the PF pci_ats. Gregor reported a deadlock here: pci_enable_sriov sriov_enable virtfn_add mutex_lock(dev->sriov->lock) # acquire sriov->lock pci_device_add device_add BUS_NOTIFY_ADD_DEVICE notifier chain iommu_bus_notifier amd_iommu_add_device # iommu_ops.add_device init_iommu_group iommu_group_get_for_dev iommu_group_add_device __iommu_attach_device amd_iommu_attach_device # iommu_ops.attach_device attach_device pci_enable_ats mutex_lock(dev->sriov->lock) # deadlock There's no reason to delay allocating the pci_ats struct, and if we allocate it for each device at enumeration-time, there's no need for locking in pci_enable_ats(). Allocate pci_ats struct during enumeration, when we initialize other capabilities. Note that this implementation requires ATS to be enabled on the PF first, before on any of the VFs because the PF controls the STU for all the VFs. Link: http://permalink.gmane.org/gmane.linux.kernel.iommu/9433 Reported-by: Gregor Dick Signed-off-by: Bjorn Helgaas Reviewed-by: Joerg Roedel --- drivers/pci/probe.c | 3 +++ 1 file changed, 3 insertions(+) (limited to 'drivers/pci/probe.c') diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c index cefd636..c206398 100644 --- a/drivers/pci/probe.c +++ b/drivers/pci/probe.c @@ -1540,6 +1540,9 @@ static void pci_init_capabilities(struct pci_dev *dev) /* Single Root I/O Virtualization */ pci_iov_init(dev); + /* Address Translation Services */ + pci_ats_init(dev); + /* Enable ACS P2P upstream forwarding */ pci_enable_acs(dev); } -- cgit v1.1