iv/linux
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

iommu: Avoid more races around device probe

Browse Source 
It turns out there are more subtle races beyond just the main part of
__iommu_probe_device() itself running in parallel - the dev_iommu_free()
on the way out of an unsuccessful probe can still manage to trip up
concurrent accesses to a device's fwspec. Thus, extend the scope of
iommu_probe_device_lock() to also serialise fwspec creation and initial
retrieval.

Reported-by: Zhenhua Huang <quic_zhenhuah@quicinc.com>
Link: https://lore.kernel.org/linux-iommu/e2e20e1c-6450-4ac5-9804-b0000acdf7de@quicinc.com/
Fixes: 01657bc14a ("iommu: Avoid races around device probe")
Signed-off-by: Robin Murphy <robin.murphy@arm.com>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Reviewed-by: André Draszik <andre.draszik@linaro.org>
Tested-by: André Draszik <andre.draszik@linaro.org>
Link: https://lore.kernel.org/r/16f433658661d7cadfea51e7c65da95826112a2b.1700071477.git.robin.murphy@arm.com
Cc: stable@vger.kernel.org
Signed-off-by: Joerg Roedel <jroedel@suse.de>
This commit is contained in:
Robin Murphy 2023-11-15 18:25:44 +00:00 committed by Joerg Roedel
parent a99583e2af
commit a2e7e59a94
4 changed files with 26 additions and 14 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

7
drivers/acpi/scan.c
View File

@ -1568,17 +1568,22 @@ static const struct iommu_ops *acpi_iommu_configure_id(struct device *dev,
int err;
const struct iommu_ops *ops;
/* Serialise to make dev->iommu stable under our potential fwspec */
mutex_lock(&iommu_probe_device_lock);
/*
* If we already translated the fwspec there is nothing left to do,
* return the iommu_ops.
*/
ops = acpi_iommu_fwspec_ops(dev);
if (ops)
if (ops) {
mutex_unlock(&iommu_probe_device_lock);
return ops;
}
err = iort_iommu_configure_id(dev, id_in);
if (err && err != -EPROBE_DEFER)
err = viot_iommu_configure(dev);
mutex_unlock(&iommu_probe_device_lock);
/*
* If we have reason to believe the IOMMU driver missed the initial

20
drivers/iommu/iommu.c
View File

@ -485,11 +485,12 @@ static void iommu_deinit_device(struct device *dev)
dev_iommu_free(dev);
}
DEFINE_MUTEX(iommu_probe_device_lock);
static int __iommu_probe_device(struct device *dev, struct list_head *group_list)
{
const struct iommu_ops *ops = dev->bus->iommu_ops;
struct iommu_group *group;
static DEFINE_MUTEX(iommu_probe_device_lock);
struct group_device *gdev;
int ret;
@ -502,17 +503,15 @@ static int __iommu_probe_device(struct device *dev, struct list_head *group_list
* probably be able to use device_lock() here to minimise the scope,
* but for now enforcing a simple global ordering is fine.
*/
mutex_lock(&iommu_probe_device_lock);
lockdep_assert_held(&iommu_probe_device_lock);
/* Device is probed already if in a group */
if (dev->iommu_group) {
ret = 0;
goto out_unlock;
}
if (dev->iommu_group)
return 0;
ret = iommu_init_device(dev, ops);
if (ret)
goto out_unlock;
return ret;
group = dev->iommu_group;
gdev = iommu_group_alloc_device(group, dev);
@ -548,7 +547,6 @@ static int __iommu_probe_device(struct device *dev, struct list_head *group_list
list_add_tail(&group->entry, group_list);
}
mutex_unlock(&group->mutex);
mutex_unlock(&iommu_probe_device_lock);
if (dev_is_pci(dev))
iommu_dma_set_pci_32bit_workaround(dev);
@ -562,8 +560,6 @@ err_put_group:
iommu_deinit_device(dev);
mutex_unlock(&group->mutex);
iommu_group_put(group);
out_unlock:
mutex_unlock(&iommu_probe_device_lock);
return ret;
}
@ -573,7 +569,9 @@ int iommu_probe_device(struct device *dev)
const struct iommu_ops *ops;
int ret;
mutex_lock(&iommu_probe_device_lock);
ret = __iommu_probe_device(dev, NULL);
mutex_unlock(&iommu_probe_device_lock);
if (ret)
return ret;
@ -1822,7 +1820,9 @@ static int probe_iommu_group(struct device *dev, void *data)
struct list_head *group_list = data;
int ret;
mutex_lock(&iommu_probe_device_lock);
ret = __iommu_probe_device(dev, group_list);
mutex_unlock(&iommu_probe_device_lock);
if (ret == -ENODEV)
ret = 0;

12
drivers/iommu/of_iommu.c
View File

@ -112,16 +112,20 @@ const struct iommu_ops *of_iommu_configure(struct device *dev,
const u32 *id)
{
const struct iommu_ops *ops = NULL;
struct iommu_fwspec *fwspec = dev_iommu_fwspec_get(dev);
struct iommu_fwspec *fwspec;
int err = NO_IOMMU;
if (!master_np)
return NULL;
/* Serialise to make dev->iommu stable under our potential fwspec */
mutex_lock(&iommu_probe_device_lock);
fwspec = dev_iommu_fwspec_get(dev);
if (fwspec) {
if (fwspec->ops)
if (fwspec->ops) {
mutex_unlock(&iommu_probe_device_lock);
return fwspec->ops;
}
/* In the deferred case, start again from scratch */
iommu_fwspec_free(dev);
}
@ -155,6 +159,8 @@ const struct iommu_ops *of_iommu_configure(struct device *dev,
fwspec = dev_iommu_fwspec_get(dev);
ops = fwspec->ops;
}
mutex_unlock(&iommu_probe_device_lock);
/*
* If we have reason to believe the IOMMU driver missed the initial
* probe for dev, replay it to get things in order.

1
include/linux/iommu.h
View File

@ -845,6 +845,7 @@ static inline void dev_iommu_priv_set(struct device *dev, void *priv)
dev->iommu->priv = priv;
}
extern struct mutex iommu_probe_device_lock;
int iommu_probe_device(struct device *dev);
int iommu_dev_enable_feature(struct device *dev, enum iommu_dev_features f);