Since commit fa7e9ecc5e1c ("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: fa7e9ecc5e1c ("iommu/s390: Tolerate repeat attach_dev calls")
Signed-off-by: Niklas Schnelle <schnelle@linux.ibm.com>
---
v4->v5:
- Unregister IOAT and set zdev->dma_table on error (Matt)
drivers/iommu/s390-iommu.c | 102 ++++++++++++++++---------------------
1 file changed, 43 insertions(+), 59 deletions(-)
diff --git a/drivers/iommu/s390-iommu.c b/drivers/iommu/s390-iommu.c
index c898bcbbce11..938998c46bd3 100644
--- a/drivers/iommu/s390-iommu.c
+++ b/drivers/iommu/s390-iommu.c
@@ -79,10 +79,36 @@ 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)
{
@@ -90,7 +116,7 @@ static int s390_iommu_attach_device(struct iommu_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;
@@ -99,23 +125,17 @@ 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));
if (cc) {
rc = -EIO;
- goto out_restore;
+ goto out_free;
}
spin_lock_irqsave(&s390_domain->list_lock, flags);
@@ -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;
@@ -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);
@@ -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;
-
- 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);
+ WARN_ON(zdev->s390_domain != to_s390_domain(domain));
- 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)
@@ -193,24 +188,13 @@ 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,
--
2.34.1On 10/6/22 10:46 AM, Niklas Schnelle wrote:
> Since commit fa7e9ecc5e1c ("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: fa7e9ecc5e1c ("iommu/s390: Tolerate repeat attach_dev calls")
> Signed-off-by: Niklas Schnelle <schnelle@linux.ibm.com>
> ---
> v4->v5:
> - Unregister IOAT and set zdev->dma_table on error (Matt)
>
...
> static int s390_iommu_attach_device(struct iommu_domain *domain,
> struct device *dev)
> {
> @@ -90,7 +116,7 @@ static int s390_iommu_attach_device(struct iommu_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;
> @@ -99,23 +125,17 @@ 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));
> if (cc) {
> rc = -EIO;
> - goto out_restore;
> + goto out_free;
> }
Hmm, with this we will leave attach_dev with a zdev->dma_table associated with this domain (not one generated via zpci_dma_init_device) and zdev->s390_domain == 0. Won't this cause both s390_domain_free and zpci_dma_exit_device() to try and free the same dma table?
I think we also have to leave with a NULL zdev->dma_table in this case too (you technically could skip the zpci_unregister_ioat)
>
> spin_lock_irqsave(&s390_domain->list_lock, flags);
> @@ -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;
> @@ -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);
>
On Thu, 2022-10-06 at 17:02 -0400, Matthew Rosato wrote:
> On 10/6/22 10:46 AM, Niklas Schnelle wrote:
> > Since commit fa7e9ecc5e1c ("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: fa7e9ecc5e1c ("iommu/s390: Tolerate repeat attach_dev calls")
> > Signed-off-by: Niklas Schnelle <schnelle@linux.ibm.com>
> > ---
> > v4->v5:
> > - Unregister IOAT and set zdev->dma_table on error (Matt)
> >
> ...
>
> > static int s390_iommu_attach_device(struct iommu_domain *domain,
> > struct device *dev)
> > {
> > @@ -90,7 +116,7 @@ static int s390_iommu_attach_device(struct iommu_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;
> > @@ -99,23 +125,17 @@ 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));
> > if (cc) {
> > rc = -EIO;
> > - goto out_restore;
> > + goto out_free;
> > }
>
> Hmm, with this we will leave attach_dev with a zdev->dma_table associated with this domain (not one generated via zpci_dma_init_device) and zdev->s390_domain == 0. Won't this cause both s390_domain_free and zpci_dma_exit_device() to try and free the same dma table?
>
> I think we also have to leave with a NULL zdev->dma_table in this case too (you technically could skip the zpci_unregister_ioat)
Argh you're right. This is I think a a bad rebase, in v4 I had the
zpci_register_ioat() use s390_domain->dma_table and only set zdev-
>dma_table after that succeeded. I seem to have lost that part
somewhere along the way. With that we zdev->dma_table would be NULL and
all would be good.
>
> >
> > spin_lock_irqsave(&s390_domain->list_lock, flags);
> > @@ -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;
> > @@ -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);
> >
On Fri, 2022-10-07 at 08:55 +0200, Niklas Schnelle wrote:
> On Thu, 2022-10-06 at 17:02 -0400, Matthew Rosato wrote:
> > On 10/6/22 10:46 AM, Niklas Schnelle wrote:
> > > Since commit fa7e9ecc5e1c ("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: fa7e9ecc5e1c ("iommu/s390: Tolerate repeat attach_dev calls")
> > > Signed-off-by: Niklas Schnelle <schnelle@linux.ibm.com>
> > > ---
> > > v4->v5:
> > > - Unregister IOAT and set zdev->dma_table on error (Matt)
> > >
> > ...
> >
> > > static int s390_iommu_attach_device(struct iommu_domain *domain,
> > > struct device *dev)
> > > {
> > > @@ -90,7 +116,7 @@ static int s390_iommu_attach_device(struct iommu_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;
> > > @@ -99,23 +125,17 @@ 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));
> > > if (cc) {
> > > rc = -EIO;
> > > - goto out_restore;
> > > + goto out_free;
> > > }
> >
> > Hmm, with this we will leave attach_dev with a zdev->dma_table associated with this domain (not one generated via zpci_dma_init_device) and zdev->s390_domain == 0. Won't this cause both s390_domain_free and zpci_dma_exit_device() to try and free the same dma table?
> >
> > I think we also have to leave with a NULL zdev->dma_table in this case too (you technically could skip the zpci_unregister_ioat)
>
> Argh you're right. This is I think a a bad rebase, in v4 I had the
> zpci_register_ioat() use s390_domain->dma_table and only set zdev-
> > dma_table after that succeeded. I seem to have lost that part
> somewhere along the way. With that we zdev->dma_table would be NULL and
> all would be good.
>
Went back to the way I did it in v4 for v6. I think I was simply an
idiot and when comparing to the state prior to the commit forgot why I
did it this way and thought it was an unneeded change..
> > >
> > > spin_lock_irqsave(&s390_domain->list_lock, flags);
> > > @@ -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;
> > > @@ -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);
> > >
>
>
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