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iommu/s390: Fix duplicate domain attachments
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Since commit fa7e9ec ("iommu/s390: Tolerate repeat attach_dev
calls") we can end up with duplicates in the list of devices attached to
a domain. This is inefficient and confusing since only one domain can
actually be in control of the IOMMU translations for a device. Fix this
by detaching the device from the previous domain, if any, on attach.
Add a WARN_ON() in case we still have attached devices on freeing the
domain. While here remove the re-attach on failure dance as it was
determined to be unlikely to help and may confuse debug and recovery.

Fixes: fa7e9ec ("iommu/s390: Tolerate repeat attach_dev calls")
Reviewed-by: Matthew Rosato <mjrosato@linux.ibm.com>
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Signed-off-by: Niklas Schnelle <schnelle@linux.ibm.com>
Link: https://lore.kernel.org/r/20221025115657.1666860-2-schnelle@linux.ibm.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>
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Niklas Schnelle authored and Joerg Roedel committed Nov 3, 2022
1 parent 30a0b95 commit bf8d2dd
Showing 1 changed file with 45 additions and 61 deletions.
106 changes: 45 additions & 61 deletions drivers/iommu/s390-iommu.c
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Original file line number Diff line number Diff line change
Expand Up @@ -79,18 +79,44 @@ static void s390_domain_free(struct iommu_domain *domain)
{
struct s390_domain *s390_domain = to_s390_domain(domain);

WARN_ON(!list_empty(&s390_domain->devices));
dma_cleanup_tables(s390_domain->dma_table);
kfree(s390_domain);
}

static void __s390_iommu_detach_device(struct zpci_dev *zdev)
{
struct s390_domain *s390_domain = zdev->s390_domain;
struct s390_domain_device *domain_device, *tmp;
unsigned long flags;

if (!s390_domain)
return;

spin_lock_irqsave(&s390_domain->list_lock, flags);
list_for_each_entry_safe(domain_device, tmp, &s390_domain->devices,
list) {
if (domain_device->zdev == zdev) {
list_del(&domain_device->list);
kfree(domain_device);
break;
}
}
spin_unlock_irqrestore(&s390_domain->list_lock, flags);

zpci_unregister_ioat(zdev, 0);
zdev->s390_domain = NULL;
zdev->dma_table = NULL;
}

static int s390_iommu_attach_device(struct iommu_domain *domain,
struct device *dev)
{
struct s390_domain *s390_domain = to_s390_domain(domain);
struct zpci_dev *zdev = to_zpci_dev(dev);
struct s390_domain_device *domain_device;
unsigned long flags;
int cc, rc;
int cc, rc = 0;

if (!zdev)
return -ENODEV;
Expand All @@ -99,24 +125,18 @@ static int s390_iommu_attach_device(struct iommu_domain *domain,
if (!domain_device)
return -ENOMEM;

if (zdev->dma_table && !zdev->s390_domain) {
cc = zpci_dma_exit_device(zdev);
if (cc) {
rc = -EIO;
goto out_free;
}
}

if (zdev->s390_domain)
zpci_unregister_ioat(zdev, 0);
__s390_iommu_detach_device(zdev);
else if (zdev->dma_table)
zpci_dma_exit_device(zdev);

zdev->dma_table = s390_domain->dma_table;
cc = zpci_register_ioat(zdev, 0, zdev->start_dma, zdev->end_dma,
virt_to_phys(zdev->dma_table));
virt_to_phys(s390_domain->dma_table));
if (cc) {
rc = -EIO;
goto out_restore;
goto out_free;
}
zdev->dma_table = s390_domain->dma_table;

spin_lock_irqsave(&s390_domain->list_lock, flags);
/* First device defines the DMA range limits */
Expand All @@ -127,9 +147,9 @@ static int s390_iommu_attach_device(struct iommu_domain *domain,
/* Allow only devices with identical DMA range limits */
} else if (domain->geometry.aperture_start != zdev->start_dma ||
domain->geometry.aperture_end != zdev->end_dma) {
rc = -EINVAL;
spin_unlock_irqrestore(&s390_domain->list_lock, flags);
goto out_restore;
rc = -EINVAL;
goto out_unregister;
}
domain_device->zdev = zdev;
zdev->s390_domain = s390_domain;
Expand All @@ -138,14 +158,9 @@ static int s390_iommu_attach_device(struct iommu_domain *domain,

return 0;

out_restore:
if (!zdev->s390_domain) {
zpci_dma_init_device(zdev);
} else {
zdev->dma_table = zdev->s390_domain->dma_table;
zpci_register_ioat(zdev, 0, zdev->start_dma, zdev->end_dma,
virt_to_phys(zdev->dma_table));
}
out_unregister:
zpci_unregister_ioat(zdev, 0);
zdev->dma_table = NULL;
out_free:
kfree(domain_device);

Expand All @@ -155,32 +170,12 @@ static int s390_iommu_attach_device(struct iommu_domain *domain,
static void s390_iommu_detach_device(struct iommu_domain *domain,
struct device *dev)
{
struct s390_domain *s390_domain = to_s390_domain(domain);
struct zpci_dev *zdev = to_zpci_dev(dev);
struct s390_domain_device *domain_device, *tmp;
unsigned long flags;
int found = 0;

if (!zdev)
return;
WARN_ON(zdev->s390_domain != to_s390_domain(domain));

spin_lock_irqsave(&s390_domain->list_lock, flags);
list_for_each_entry_safe(domain_device, tmp, &s390_domain->devices,
list) {
if (domain_device->zdev == zdev) {
list_del(&domain_device->list);
kfree(domain_device);
found = 1;
break;
}
}
spin_unlock_irqrestore(&s390_domain->list_lock, flags);

if (found && (zdev->s390_domain == s390_domain)) {
zdev->s390_domain = NULL;
zpci_unregister_ioat(zdev, 0);
zpci_dma_init_device(zdev);
}
__s390_iommu_detach_device(zdev);
zpci_dma_init_device(zdev);
}

static struct iommu_device *s390_iommu_probe_device(struct device *dev)
Expand All @@ -198,24 +193,13 @@ static struct iommu_device *s390_iommu_probe_device(struct device *dev)
static void s390_iommu_release_device(struct device *dev)
{
struct zpci_dev *zdev = to_zpci_dev(dev);
struct iommu_domain *domain;

/*
* This is a workaround for a scenario where the IOMMU API common code
* "forgets" to call the detach_dev callback: After binding a device
* to vfio-pci and completing the VFIO_SET_IOMMU ioctl (which triggers
* the attach_dev), removing the device via
* "echo 1 > /sys/bus/pci/devices/.../remove" won't trigger detach_dev,
* only release_device will be called via the BUS_NOTIFY_REMOVED_DEVICE
* notifier.
*
* So let's call detach_dev from here if it hasn't been called before.
* release_device is expected to detach any domain currently attached
* to the device, but keep it attached to other devices in the group.
*/
if (zdev && zdev->s390_domain) {
domain = iommu_get_domain_for_dev(dev);
if (domain)
s390_iommu_detach_device(domain, dev);
}
if (zdev)
__s390_iommu_detach_device(zdev);
}

static int s390_iommu_update_trans(struct s390_domain *s390_domain,
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