Hey Jan, On Wed, Sep 27, 2017 at 04:19:15PM +0200, Jan Kiszka wrote: > If we could drop the dmar_global_lock around bus_register_notifier in > dmar_dev_scope_init, the issue above would likely be resolved.
That is true. Can you please try this patch? >From dd7685f84d3954f9361bfb4290fb8a0dd033097a Mon Sep 17 00:00:00 2001 From: Joerg Roedel <[email protected]> Date: Fri, 6 Oct 2017 15:00:53 +0200 Subject: [PATCH] iommu/vt-d: Don't register bus-notifier under dmar_global_lock The notifier function will take the dmar_global_lock too, so lockdep complains about inverse locking order when the notifier is registered under the dmar_global_lock. Reported-by: Jan Kiszka <[email protected]> Fixes: 59ce0515cdaf ('iommu/vt-d: Update DRHD/RMRR/ATSR device scope caches when PCI hotplug happens') Signed-off-by: Joerg Roedel <[email protected]> --- drivers/iommu/dmar.c | 7 +++++-- drivers/iommu/intel-iommu.c | 10 ++++++++++ include/linux/dmar.h | 1 + 3 files changed, 16 insertions(+), 2 deletions(-) diff --git a/drivers/iommu/dmar.c b/drivers/iommu/dmar.c index 57c920c1372d..1ea7cd537873 100644 --- a/drivers/iommu/dmar.c +++ b/drivers/iommu/dmar.c @@ -801,13 +801,16 @@ int __init dmar_dev_scope_init(void) dmar_free_pci_notify_info(info); } } - - bus_register_notifier(&pci_bus_type, &dmar_pci_bus_nb); } return dmar_dev_scope_status; } +void dmar_register_bus_notifier(void) +{ + bus_register_notifier(&pci_bus_type, &dmar_pci_bus_nb); +} + int __init dmar_table_init(void) { diff --git a/drivers/iommu/intel-iommu.c b/drivers/iommu/intel-iommu.c index 6784a05dd6b2..934cef924461 100644 --- a/drivers/iommu/intel-iommu.c +++ b/drivers/iommu/intel-iommu.c @@ -4752,6 +4752,16 @@ int __init intel_iommu_init(void) goto out_free_dmar; } + up_write(&dmar_global_lock); + + /* + * The bus notifier takes the dmar_global_lock, so lockdep will + * complain later when we register it under the lock. + */ + dmar_register_bus_notifier(); + + down_write(&dmar_global_lock); + if (no_iommu || dmar_disabled) { /* * We exit the function here to ensure IOMMU's remapping and diff --git a/include/linux/dmar.h b/include/linux/dmar.h index e8ffba1052d3..e2433bc50210 100644 --- a/include/linux/dmar.h +++ b/include/linux/dmar.h @@ -112,6 +112,7 @@ static inline bool dmar_rcu_check(void) extern int dmar_table_init(void); extern int dmar_dev_scope_init(void); +extern void dmar_register_bus_notifier(void); extern int dmar_parse_dev_scope(void *start, void *end, int *cnt, struct dmar_dev_scope **devices, u16 segment); extern void *dmar_alloc_dev_scope(void *start, void *end, int *cnt); -- 2.13.6
