lkml.org 
[lkml]   [2017]   [Oct]   [6]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
Date
From
Subject[PATCH] iommu/vt-d: Don't register bus-notifier under
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 <jroedel@suse.de>
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 <jan.kiszka@siemens.com>
Fixes: 59ce0515cdaf ('iommu/vt-d: Update DRHD/RMRR/ATSR device scope caches when PCI hotplug happens')
Signed-off-by: Joerg Roedel <jroedel@suse.de>
---
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
\
 
 \ /
  Last update: 2017-10-06 15:09    [W:0.102 / U:1.004 seconds]
©2003-2017 Jasper Spaans. hosted at Digital OceanAdvertise on this site