Re: [PATCH v2] iommu/amd: remove obsolete domain pointer warning on release

[Jason Gunthorpe <jgg@ziepe.ca>]

On Tue, Oct 13, 2026 at 03:23:56PM -0700, Kevin Mitchell wrote:
> A warning is triggered in amd_iommu_release_device() on removal of a
> device with an IOMMU_RESV_DIRECT region. The warning is based on the
> false assumption that correct attachment to the release_domain will
> always result in a NULL dev_data->domain pointer. For devices with
> IOMMU_RESV_DIRECT (and consequently dev->iommu->require_direct), the
> release domain is the permanent identity_domain which sets
> itself to dev_data->domain on attach.
> 
> This behaviour was added in commit e94160488e65 ("iommu: Generic support
> for RMRs during device release"). Commit c21b34762e2f ("iommu/amd: Set
> release_domain to blocked_domain") caused it to take effect for AMD
> IOMMU.
> 
> Remove the warning as it is no longer strictly an error to have a non-NULL
> domain pointer. As this leaves amd_iommu_release_device() empty, remove it.
> 
> The warning was observed for a device with direct mapped region:
> 
> /sys/bus/pci/devices/0000:04:00.0/iommu_group/reserved_regions:
> 
>   0x00000000fee00000 0x00000000feefffff msi
>   0x000000fd00000000 0x000000ffffffffff reserved
>   0x0000fffd00000000 0x0000ffffffffffff direct
> 
> Upon hotunplug:
> 
> [   28.715475] pcieport 0000:00:03.1: pciehp: Slot(0-3): Link Down
> [   28.715482] pcieport 0000:00:03.1: pciehp: Slot(0-3): Card not present
> [   28.715601] ------------[ cut here ]------------
> [   28.715603] WARNING: drivers/iommu/amd/iommu.c:2521 at amd_iommu_release_device+0x5d/0x70, CPU#4: irq/29-pciehp/99
> [   28.715657] RIP: 0010:amd_iommu_release_device+0x5d/0x70
> [   28.715687] Call Trace:
> [   28.715689]  <TASK>
> [   28.715694]  iommu_deinit_device+0x84/0x110
> [   28.715699]  __iommu_group_remove_device+0xa8/0xd0
> [   28.715703]  iommu_bus_notifier+0x48/0x70
> [   28.715707]  notifier_call_chain+0x48/0xe0
> [   28.715712]  blocking_notifier_call_chain+0x45/0x60
> [   28.715716]  bus_notify+0x3b/0x60
> [   28.715720]  device_del+0x259/0x3b0
> [   28.715730]  pci_remove_bus_device+0x85/0x100
> [   28.715735]  pciehp_unconfigure_device+0x9d/0x180
> [   28.715743]  __pciehp_disable_slot+0x47/0xe0
> [   28.715747]  pciehp_handle_presence_or_link_change+0x80/0x5e0
> [   28.715753]  pciehp_ist+0x162/0x290
> 
> Fixes: c21b34762e2f ("iommu/amd: Set release_domain to blocked_domain")
> Cc: stable@vger.kernel.org
> Signed-off-by: Kevin Mitchell <kevmitch@arista.com>
> ---
> Changes in v2:
> - Remove the warning alltogether as well as the now-empty
>   amd_iommu_release_device()
> - Link to v1: https://lore.kernel.org/r/20261008202530.14501-2-kevmitch@arista.com
> 
>  drivers/iommu/amd/iommu.c | 17 ++++-------------
>  1 file changed, 4 insertions(+), 13 deletions(-)

Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>

Jason