Re: [PATCH v2 03/14] iommu: Move bus setup to IOMMU device registration
On 2022-07-05 05:51, Baolu Lu wrote: Hi Robin, On 2022/4/30 02:06, Robin Murphy wrote: On 29/04/2022 9:50 am, Robin Murphy wrote: On 2022-04-29 07:57, Baolu Lu wrote: Hi Robin, On 2022/4/28 21:18, Robin Murphy wrote: Move the bus setup to iommu_device_register(). This should allow bus_iommu_probe() to be correctly replayed for multiple IOMMU instances, and leaves bus_set_iommu() as a glorified no-op to be cleaned up next. I re-fetched the latest patches on https://gitlab.arm.com/linux-arm/linux-rm/-/commits/iommu/bus and rolled back the head to "iommu: Cleanup bus_set_iommu". The test machine still hangs during boot. I went through the code. It seems that the .probe_device for Intel IOMMU driver can't handle the probe replay well. It always assumes that the device has never been probed. Hmm, but probe_iommu_group() is supposed to prevent the __iommu_probe_device() call even happening if the device *has* already been probed before :/ I've still got an old Intel box spare in the office so I'll rig that up and see if I can see what might be going on here... OK, on a Xeon with two DMAR units, this seems to boot OK with or without patch #1, so it doesn't seem to be a general problem with replaying in iommu_device_register(), or with platform devices. Not sure where to go from here... :/ The kernel boot panic message: [ 6.639432] BUG: kernel NULL pointer dereference, address: 0028 [ 6.743829] #PF: supervisor read access in kernel mode [ 6.743829] #PF: error_code(0x) - not-present page [ 6.743829] PGD 0 [ 6.743829] Oops: [#1] PREEMPT SMP NOPTI [ 6.743829] CPU: 0 PID: 1 Comm: swapper/0 Tainted: G I 5.19.0-rc3+ #182 [ 6.743829] RIP: 0010:__iommu_probe_device+0x115/0x200 [ 6.743829] Code: 89 ff e8 3e e1 ff ff 48 85 c0 0f 85 47 ff ff ff 41 bd f4 ff ff ff eb 83 48 8b 83 d8 02 00 00 48 89 df 48 8b 40 38 48 8b 40 10 <48> 8b 40 28 ff d0 0f 1f 00 48 89 c1 48 85 c0 0f 84 b7 00 00 00 48 [ 6.743829] RSP: :ff30605c00063d40 EFLAGS: 00010246 [ 6.743829] RAX: RBX: ff128b9c5fdc90d0 RCX: [ 6.743829] RDX: 8001 RSI: 0246 RDI: ff128b9c5fdc90d0 [ 6.743829] RBP: b60c34e0 R08: b68664d0 R09: ff128b9501d4ce40 [ 6.743829] R10: b6267096 R11: ff128b950014c267 R12: ff30605c00063de0 [ 6.743829] R13: 001b9d28 R14: ff128b95001b9d28 R15: ff128b9c5fdc93a8 [ 6.743829] FS: () GS:ff128b9c5fc0() knlGS: [ 6.743829] CS: 0010 DS: ES: CR0: 80050033 [ 6.743829] CR2: 0028 CR3: 000149210001 CR4: 00771ef0 [ 6.743829] DR0: DR1: DR2: [ 6.743829] DR3: DR6: 07f0 DR7: 0400 [ 6.743829] PKRU: 5554 [ 6.743829] Call Trace: [ 6.743829] [ 6.743829] ? _raw_spin_lock_irqsave+0x17/0x40 [ 6.743829] ? __iommu_probe_device+0x200/0x200 [ 6.743829] probe_iommu_group+0x2d/0x40 [ 6.743829] bus_for_each_dev+0x74/0xc0 [ 6.743829] bus_iommu_probe+0x48/0x2d0 [ 6.743829] iommu_device_register+0xde/0x120 [ 6.743829] intel_iommu_init+0x35f/0x5f2 [ 6.743829] ? iommu_setup+0x27d/0x27d [ 6.743829] ? rdinit_setup+0x2c/0x2c [ 6.743829] pci_iommu_init+0xe/0x32 [ 6.743829] do_one_initcall+0x41/0x200 [ 6.743829] kernel_init_freeable+0x1de/0x228 [ 6.743829] ? rest_init+0xc0/0xc0 [ 6.743829] kernel_init+0x16/0x120 [ 6.743829] ret_from_fork+0x1f/0x30 [ 6.743829] [ 6.743829] Modules linked in: [ 6.743829] CR2: 0028 [ 6.743829] ---[ end trace ]--- [ 6.743829] RIP: 0010:__iommu_probe_device+0x115/0x200 [ 6.743829] Code: 89 ff e8 3e e1 ff ff 48 85 c0 0f 85 47 ff ff ff 41 bd f4 ff ff ff eb 83 48 8b 83 d8 02 00 00 48 89 df 48 8b 40 38 48 8b 40 10 <48> 8b 40 28 ff d0 0f 1f 00 48 89 c1 48 85 c0 0f 84 b7 00 00 00 48 [ 6.743829] RSP: :ff30605c00063d40 EFLAGS: 00010246 [ 6.743829] RAX: RBX: ff128b9c5fdc90d0 RCX: [ 6.743829] RDX: 8001 RSI: 0246 RDI: ff128b9c5fdc90d0 [ 6.743829] RBP: b60c34e0 R08: b68664d0 R09: ff128b9501d4ce40 [ 6.743829] R10: b6267096 R11: ff128b950014c267 R12: ff30605c00063de0 [ 6.743829] R13: 001b9d28 R14: ff128b95001b9d28 R15: ff128b9c5fdc93a8 [ 6.743829] FS: () GS:ff128b9c5fc0() knlGS: [ 6.743829] CS: 0010 DS: ES: CR0: 80050033 [ 6.743829] CR2: 0028 CR3: 000149210001 CR4: 00771ef0 [ 6.743829] DR0: DR1: DR2: [ 6.743829] DR3: DR6: 07f0 DR7: 0400 [ 6.743829] PKRU: 5554 [ 6.743829] Kernel panic - not syncing: Fatal exception [
Re: [PATCH v2 03/14] iommu: Move bus setup to IOMMU device registration
Hi Robin, On 2022/4/30 02:06, Robin Murphy wrote: On 29/04/2022 9:50 am, Robin Murphy wrote: On 2022-04-29 07:57, Baolu Lu wrote: Hi Robin, On 2022/4/28 21:18, Robin Murphy wrote: Move the bus setup to iommu_device_register(). This should allow bus_iommu_probe() to be correctly replayed for multiple IOMMU instances, and leaves bus_set_iommu() as a glorified no-op to be cleaned up next. I re-fetched the latest patches on https://gitlab.arm.com/linux-arm/linux-rm/-/commits/iommu/bus and rolled back the head to "iommu: Cleanup bus_set_iommu". The test machine still hangs during boot. I went through the code. It seems that the .probe_device for Intel IOMMU driver can't handle the probe replay well. It always assumes that the device has never been probed. Hmm, but probe_iommu_group() is supposed to prevent the __iommu_probe_device() call even happening if the device *has* already been probed before :/ I've still got an old Intel box spare in the office so I'll rig that up and see if I can see what might be going on here... OK, on a Xeon with two DMAR units, this seems to boot OK with or without patch #1, so it doesn't seem to be a general problem with replaying in iommu_device_register(), or with platform devices. Not sure where to go from here... :/ The kernel boot panic message: [6.639432] BUG: kernel NULL pointer dereference, address: 0028 [6.743829] #PF: supervisor read access in kernel mode [6.743829] #PF: error_code(0x) - not-present page [6.743829] PGD 0 [6.743829] Oops: [#1] PREEMPT SMP NOPTI [6.743829] CPU: 0 PID: 1 Comm: swapper/0 Tainted: G I 5.19.0-rc3+ #182 [6.743829] RIP: 0010:__iommu_probe_device+0x115/0x200 [6.743829] Code: 89 ff e8 3e e1 ff ff 48 85 c0 0f 85 47 ff ff ff 41 bd f4 ff ff ff eb 83 48 8b 83 d8 02 00 00 48 89 df 48 8b 40 38 48 8b 40 10 <48> 8b 40 28 ff d0 0f 1f 00 48 89 c1 48 85 c0 0f 84 b7 00 00 00 48 [6.743829] RSP: :ff30605c00063d40 EFLAGS: 00010246 [6.743829] RAX: RBX: ff128b9c5fdc90d0 RCX: [6.743829] RDX: 8001 RSI: 0246 RDI: ff128b9c5fdc90d0 [6.743829] RBP: b60c34e0 R08: b68664d0 R09: ff128b9501d4ce40 [6.743829] R10: b6267096 R11: ff128b950014c267 R12: ff30605c00063de0 [6.743829] R13: 001b9d28 R14: ff128b95001b9d28 R15: ff128b9c5fdc93a8 [6.743829] FS: () GS:ff128b9c5fc0() knlGS: [6.743829] CS: 0010 DS: ES: CR0: 80050033 [6.743829] CR2: 0028 CR3: 000149210001 CR4: 00771ef0 [6.743829] DR0: DR1: DR2: [6.743829] DR3: DR6: 07f0 DR7: 0400 [6.743829] PKRU: 5554 [6.743829] Call Trace: [6.743829] [6.743829] ? _raw_spin_lock_irqsave+0x17/0x40 [6.743829] ? __iommu_probe_device+0x200/0x200 [6.743829] probe_iommu_group+0x2d/0x40 [6.743829] bus_for_each_dev+0x74/0xc0 [6.743829] bus_iommu_probe+0x48/0x2d0 [6.743829] iommu_device_register+0xde/0x120 [6.743829] intel_iommu_init+0x35f/0x5f2 [6.743829] ? iommu_setup+0x27d/0x27d [6.743829] ? rdinit_setup+0x2c/0x2c [6.743829] pci_iommu_init+0xe/0x32 [6.743829] do_one_initcall+0x41/0x200 [6.743829] kernel_init_freeable+0x1de/0x228 [6.743829] ? rest_init+0xc0/0xc0 [6.743829] kernel_init+0x16/0x120 [6.743829] ret_from_fork+0x1f/0x30 [6.743829] [6.743829] Modules linked in: [6.743829] CR2: 0028 [6.743829] ---[ end trace ]--- [6.743829] RIP: 0010:__iommu_probe_device+0x115/0x200 [6.743829] Code: 89 ff e8 3e e1 ff ff 48 85 c0 0f 85 47 ff ff ff 41 bd f4 ff ff ff eb 83 48 8b 83 d8 02 00 00 48 89 df 48 8b 40 38 48 8b 40 10 <48> 8b 40 28 ff d0 0f 1f 00 48 89 c1 48 85 c0 0f 84 b7 00 00 00 48 [6.743829] RSP: :ff30605c00063d40 EFLAGS: 00010246 [6.743829] RAX: RBX: ff128b9c5fdc90d0 RCX: [6.743829] RDX: 8001 RSI: 0246 RDI: ff128b9c5fdc90d0 [6.743829] RBP: b60c34e0 R08: b68664d0 R09: ff128b9501d4ce40 [6.743829] R10: b6267096 R11: ff128b950014c267 R12: ff30605c00063de0 [6.743829] R13: 001b9d28 R14: ff128b95001b9d28 R15: ff128b9c5fdc93a8 [6.743829] FS: () GS:ff128b9c5fc0() knlGS: [6.743829] CS: 0010 DS: ES: CR0: 80050033 [6.743829] CR2: 0028 CR3: 000149210001 CR4: 00771ef0 [6.743829] DR0: DR1: DR2: [6.743829] DR3: DR6: 07f0 DR7: 0400 [6.743829] PKRU: 5554 [6.743829] Kernel panic - not syncing: Fatal exception [6.743829] ---[ end Kernel panic - not syncing:
Re: [PATCH v2 03/14] iommu: Move bus setup to IOMMU device registration
On 29/04/2022 9:50 am, Robin Murphy wrote: On 2022-04-29 07:57, Baolu Lu wrote: Hi Robin, On 2022/4/28 21:18, Robin Murphy wrote: Move the bus setup to iommu_device_register(). This should allow bus_iommu_probe() to be correctly replayed for multiple IOMMU instances, and leaves bus_set_iommu() as a glorified no-op to be cleaned up next. I re-fetched the latest patches on https://gitlab.arm.com/linux-arm/linux-rm/-/commits/iommu/bus and rolled back the head to "iommu: Cleanup bus_set_iommu". The test machine still hangs during boot. I went through the code. It seems that the .probe_device for Intel IOMMU driver can't handle the probe replay well. It always assumes that the device has never been probed. Hmm, but probe_iommu_group() is supposed to prevent the __iommu_probe_device() call even happening if the device *has* already been probed before :/ I've still got an old Intel box spare in the office so I'll rig that up and see if I can see what might be going on here... OK, on a Xeon with two DMAR units, this seems to boot OK with or without patch #1, so it doesn't seem to be a general problem with replaying in iommu_device_register(), or with platform devices. Not sure where to go from here... :/ Cheers, Robin. ___ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu
Re: [PATCH v2 03/14] iommu: Move bus setup to IOMMU device registration
On 2022-04-29 07:57, Baolu Lu wrote:
Hi Robin,
On 2022/4/28 21:18, Robin Murphy wrote:
Move the bus setup to iommu_device_register(). This should allow
bus_iommu_probe() to be correctly replayed for multiple IOMMU instances,
and leaves bus_set_iommu() as a glorified no-op to be cleaned up next.
I re-fetched the latest patches on
https://gitlab.arm.com/linux-arm/linux-rm/-/commits/iommu/bus
and rolled back the head to "iommu: Cleanup bus_set_iommu".
The test machine still hangs during boot.
I went through the code. It seems that the .probe_device for Intel IOMMU
driver can't handle the probe replay well. It always assumes that the
device has never been probed.
Hmm, but probe_iommu_group() is supposed to prevent the
__iommu_probe_device() call even happening if the device *has* already
been probed before :/
I've still got an old Intel box spare in the office so I'll rig that up
and see if I can see what might be going on here...
Thanks,
Robin.
Best regards,
baolu
At this point we can also handle cleanup better than just rolling back
the most-recently-touched bus upon failure - which may release devices
owned by other already-registered instances, and still leave devices on
other buses with dangling pointers to the failed instance. Now it's easy
to clean up the exact footprint of a given instance, no more, no less.
Tested-by: Marek Szyprowski
Signed-off-by: Robin Murphy
---
drivers/iommu/iommu.c | 51 +++
1 file changed, 27 insertions(+), 24 deletions(-)
diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
index 6c4621afc8cf..c89af4dc54c2 100644
--- a/drivers/iommu/iommu.c
+++ b/drivers/iommu/iommu.c
@@ -175,6 +175,14 @@ static int __init iommu_subsys_init(void)
}
subsys_initcall(iommu_subsys_init);
+static int remove_iommu_group(struct device *dev, void *data)
+{
+ if (dev->iommu && dev->iommu->iommu_dev == data)
+ iommu_release_device(dev);
+
+ return 0;
+}
+
/**
* iommu_device_register() - Register an IOMMU hardware instance
* @iommu: IOMMU handle for the instance
@@ -197,12 +205,29 @@ int iommu_device_register(struct iommu_device
*iommu,
spin_lock(_device_lock);
list_add_tail(>list, _device_list);
spin_unlock(_device_lock);
+
+ for (int i = 0; i < ARRAY_SIZE(iommu_buses); i++) {
+ struct bus_type *bus = iommu_buses[i];
+ int err;
+
+ WARN_ON(bus->iommu_ops && bus->iommu_ops != ops);
+ bus->iommu_ops = ops;
+ err = bus_iommu_probe(bus);
+ if (err) {
+ iommu_device_unregister(iommu);
+ return err;
+ }
+ }
+
return 0;
}
EXPORT_SYMBOL_GPL(iommu_device_register);
void iommu_device_unregister(struct iommu_device *iommu)
{
+ for (int i = 0; i < ARRAY_SIZE(iommu_buses); i++)
+ bus_for_each_dev(iommu_buses[i], NULL, iommu,
remove_iommu_group);
+
spin_lock(_device_lock);
list_del(>list);
spin_unlock(_device_lock);
@@ -1655,13 +1680,6 @@ static int probe_iommu_group(struct device
*dev, void *data)
return ret;
}
-static int remove_iommu_group(struct device *dev, void *data)
-{
- iommu_release_device(dev);
-
- return 0;
-}
-
static int iommu_bus_notifier(struct notifier_block *nb,
unsigned long action, void *data)
{
@@ -1884,27 +1902,12 @@ static int iommu_bus_init(struct bus_type *bus)
*/
int bus_set_iommu(struct bus_type *bus, const struct iommu_ops *ops)
{
- int err;
-
- if (ops == NULL) {
- bus->iommu_ops = NULL;
- return 0;
- }
-
- if (bus->iommu_ops != NULL)
+ if (bus->iommu_ops && ops && bus->iommu_ops != ops)
return -EBUSY;
bus->iommu_ops = ops;
- /* Do IOMMU specific setup for this bus-type */
- err = bus_iommu_probe(bus);
- if (err) {
- /* Clean up */
- bus_for_each_dev(bus, NULL, NULL, remove_iommu_group);
- bus->iommu_ops = NULL;
- }
-
- return err;
+ return 0;
}
EXPORT_SYMBOL_GPL(bus_set_iommu);
___
iommu mailing list
iommu@lists.linux-foundation.org
https://lists.linuxfoundation.org/mailman/listinfo/iommu
Re: [PATCH v2 03/14] iommu: Move bus setup to IOMMU device registration
Hi Robin,
On 2022/4/28 21:18, Robin Murphy wrote:
Move the bus setup to iommu_device_register(). This should allow
bus_iommu_probe() to be correctly replayed for multiple IOMMU instances,
and leaves bus_set_iommu() as a glorified no-op to be cleaned up next.
I re-fetched the latest patches on
https://gitlab.arm.com/linux-arm/linux-rm/-/commits/iommu/bus
and rolled back the head to "iommu: Cleanup bus_set_iommu".
The test machine still hangs during boot.
I went through the code. It seems that the .probe_device for Intel IOMMU
driver can't handle the probe replay well. It always assumes that the
device has never been probed.
Best regards,
baolu
At this point we can also handle cleanup better than just rolling back
the most-recently-touched bus upon failure - which may release devices
owned by other already-registered instances, and still leave devices on
other buses with dangling pointers to the failed instance. Now it's easy
to clean up the exact footprint of a given instance, no more, no less.
Tested-by: Marek Szyprowski
Signed-off-by: Robin Murphy
---
drivers/iommu/iommu.c | 51 +++
1 file changed, 27 insertions(+), 24 deletions(-)
diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
index 6c4621afc8cf..c89af4dc54c2 100644
--- a/drivers/iommu/iommu.c
+++ b/drivers/iommu/iommu.c
@@ -175,6 +175,14 @@ static int __init iommu_subsys_init(void)
}
subsys_initcall(iommu_subsys_init);
+static int remove_iommu_group(struct device *dev, void *data)
+{
+ if (dev->iommu && dev->iommu->iommu_dev == data)
+ iommu_release_device(dev);
+
+ return 0;
+}
+
/**
* iommu_device_register() - Register an IOMMU hardware instance
* @iommu: IOMMU handle for the instance
@@ -197,12 +205,29 @@ int iommu_device_register(struct iommu_device *iommu,
spin_lock(_device_lock);
list_add_tail(>list, _device_list);
spin_unlock(_device_lock);
+
+ for (int i = 0; i < ARRAY_SIZE(iommu_buses); i++) {
+ struct bus_type *bus = iommu_buses[i];
+ int err;
+
+ WARN_ON(bus->iommu_ops && bus->iommu_ops != ops);
+ bus->iommu_ops = ops;
+ err = bus_iommu_probe(bus);
+ if (err) {
+ iommu_device_unregister(iommu);
+ return err;
+ }
+ }
+
return 0;
}
EXPORT_SYMBOL_GPL(iommu_device_register);
void iommu_device_unregister(struct iommu_device *iommu)
{
+ for (int i = 0; i < ARRAY_SIZE(iommu_buses); i++)
+ bus_for_each_dev(iommu_buses[i], NULL, iommu,
remove_iommu_group);
+
spin_lock(_device_lock);
list_del(>list);
spin_unlock(_device_lock);
@@ -1655,13 +1680,6 @@ static int probe_iommu_group(struct device *dev, void
*data)
return ret;
}
-static int remove_iommu_group(struct device *dev, void *data)
-{
- iommu_release_device(dev);
-
- return 0;
-}
-
static int iommu_bus_notifier(struct notifier_block *nb,
unsigned long action, void *data)
{
@@ -1884,27 +1902,12 @@ static int iommu_bus_init(struct bus_type *bus)
*/
int bus_set_iommu(struct bus_type *bus, const struct iommu_ops *ops)
{
- int err;
-
- if (ops == NULL) {
- bus->iommu_ops = NULL;
- return 0;
- }
-
- if (bus->iommu_ops != NULL)
+ if (bus->iommu_ops && ops && bus->iommu_ops != ops)
return -EBUSY;
bus->iommu_ops = ops;
- /* Do IOMMU specific setup for this bus-type */
- err = bus_iommu_probe(bus);
- if (err) {
- /* Clean up */
- bus_for_each_dev(bus, NULL, NULL, remove_iommu_group);
- bus->iommu_ops = NULL;
- }
-
- return err;
+ return 0;
}
EXPORT_SYMBOL_GPL(bus_set_iommu);
___
iommu mailing list
iommu@lists.linux-foundation.org
https://lists.linuxfoundation.org/mailman/listinfo/iommu
[PATCH v2 03/14] iommu: Move bus setup to IOMMU device registration
Move the bus setup to iommu_device_register(). This should allow
bus_iommu_probe() to be correctly replayed for multiple IOMMU instances,
and leaves bus_set_iommu() as a glorified no-op to be cleaned up next.
At this point we can also handle cleanup better than just rolling back
the most-recently-touched bus upon failure - which may release devices
owned by other already-registered instances, and still leave devices on
other buses with dangling pointers to the failed instance. Now it's easy
to clean up the exact footprint of a given instance, no more, no less.
Tested-by: Marek Szyprowski
Signed-off-by: Robin Murphy
---
drivers/iommu/iommu.c | 51 +++
1 file changed, 27 insertions(+), 24 deletions(-)
diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
index 6c4621afc8cf..c89af4dc54c2 100644
--- a/drivers/iommu/iommu.c
+++ b/drivers/iommu/iommu.c
@@ -175,6 +175,14 @@ static int __init iommu_subsys_init(void)
}
subsys_initcall(iommu_subsys_init);
+static int remove_iommu_group(struct device *dev, void *data)
+{
+ if (dev->iommu && dev->iommu->iommu_dev == data)
+ iommu_release_device(dev);
+
+ return 0;
+}
+
/**
* iommu_device_register() - Register an IOMMU hardware instance
* @iommu: IOMMU handle for the instance
@@ -197,12 +205,29 @@ int iommu_device_register(struct iommu_device *iommu,
spin_lock(_device_lock);
list_add_tail(>list, _device_list);
spin_unlock(_device_lock);
+
+ for (int i = 0; i < ARRAY_SIZE(iommu_buses); i++) {
+ struct bus_type *bus = iommu_buses[i];
+ int err;
+
+ WARN_ON(bus->iommu_ops && bus->iommu_ops != ops);
+ bus->iommu_ops = ops;
+ err = bus_iommu_probe(bus);
+ if (err) {
+ iommu_device_unregister(iommu);
+ return err;
+ }
+ }
+
return 0;
}
EXPORT_SYMBOL_GPL(iommu_device_register);
void iommu_device_unregister(struct iommu_device *iommu)
{
+ for (int i = 0; i < ARRAY_SIZE(iommu_buses); i++)
+ bus_for_each_dev(iommu_buses[i], NULL, iommu,
remove_iommu_group);
+
spin_lock(_device_lock);
list_del(>list);
spin_unlock(_device_lock);
@@ -1655,13 +1680,6 @@ static int probe_iommu_group(struct device *dev, void
*data)
return ret;
}
-static int remove_iommu_group(struct device *dev, void *data)
-{
- iommu_release_device(dev);
-
- return 0;
-}
-
static int iommu_bus_notifier(struct notifier_block *nb,
unsigned long action, void *data)
{
@@ -1884,27 +1902,12 @@ static int iommu_bus_init(struct bus_type *bus)
*/
int bus_set_iommu(struct bus_type *bus, const struct iommu_ops *ops)
{
- int err;
-
- if (ops == NULL) {
- bus->iommu_ops = NULL;
- return 0;
- }
-
- if (bus->iommu_ops != NULL)
+ if (bus->iommu_ops && ops && bus->iommu_ops != ops)
return -EBUSY;
bus->iommu_ops = ops;
- /* Do IOMMU specific setup for this bus-type */
- err = bus_iommu_probe(bus);
- if (err) {
- /* Clean up */
- bus_for_each_dev(bus, NULL, NULL, remove_iommu_group);
- bus->iommu_ops = NULL;
- }
-
- return err;
+ return 0;
}
EXPORT_SYMBOL_GPL(bus_set_iommu);
--
2.35.3.dirty
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