iommu/arm-smmu-v3: Fix iommu_device_probe bug due to duplicated stream ids

ASPEED VGA card has two built-in devices:
 0008:06:00.0 PCI bridge: ASPEED Technology, Inc. AST1150 PCI-to-PCI Bridge (rev 06)
 0008:07:00.0 VGA compatible controller: ASPEED Technology, Inc. ASPEED Graphics Family (rev 52)

Its toplogy looks like this:
 +-[0008:00]---00.0-[01-09]--+-00.0-[02-09]--+-00.0-[03]----00.0  Sandisk Corp Device 5017
                             |               +-01.0-[04]--
                             |               +-02.0-[05]----00.0  NVIDIA Corporation Device
                             |               +-03.0-[06-07]----00.0-[07]----00.0  ASPEED Technology, Inc. ASPEED Graphics Family
                             |               +-04.0-[08]----00.0  Renesas Technology Corp. uPD720201 USB 3.0 Host Controller
                             |               \-05.0-[09]----00.0  Realtek Semiconductor Co., Ltd. RTL8111/8168/8411 PCI Express Gigabit Ethernet Controller
                             \-00.1  PMC-Sierra Inc. Device 4028

The IORT logic populaties two identical IDs into the fwspec->ids array via
DMA aliasing in iort_pci_iommu_init() called by pci_for_each_dma_alias().

Though the SMMU driver had been able to handle this situation since commit
563b5cbe334e ("iommu/arm-smmu-v3: Cope with duplicated Stream IDs"), that
got broken by the later commit cdf315f907d4 ("iommu/arm-smmu-v3: Maintain
a SID->device structure"), which ended up with allocating separate streams
with the same stuffing.

On a kernel prior to v6.15-rc1, there has been an overlooked warning:
  pci 0008:07:00.0: vgaarb: setting as boot VGA device
  pci 0008:07:00.0: vgaarb: bridge control possible
  pci 0008:07:00.0: vgaarb: VGA device added: decodes=io+mem,owns=none,locks=none
  pcieport 0008:06:00.0: Adding to iommu group 14
  ast 0008:07:00.0: stream 67328 already in tree   <===== WARNING
  ast 0008:07:00.0: enabling device (0002 -> 0003)
  ast 0008:07:00.0: Using default configuration
  ast 0008:07:00.0: AST 2600 detected
  ast 0008:07:00.0: [drm] Using analog VGA
  ast 0008:07:00.0: [drm] dram MCLK=396 Mhz type=1 bus_width=16
  [drm] Initialized ast 0.1.0 for 0008:07:00.0 on minor 0
  ast 0008:07:00.0: [drm] fb0: astdrmfb frame buffer device

With v6.15-rc, since the commit bcb81ac6ae3c ("iommu: Get DT/ACPI parsing
into the proper probe path"), the error returned with the warning is moved
to the SMMU device probe flow:
  arm_smmu_probe_device+0x15c/0x4c0
  __iommu_probe_device+0x150/0x4f8
  probe_iommu_group+0x44/0x80
  bus_for_each_dev+0x7c/0x100
  bus_iommu_probe+0x48/0x1a8
  iommu_device_register+0xb8/0x178
  arm_smmu_device_probe+0x1350/0x1db0
which then fails the entire SMMU driver probe:
  pci 0008:06:00.0: Adding to iommu group 21
  pci 0008:07:00.0: stream 67328 already in tree
  arm-smmu-v3 arm-smmu-v3.9.auto: Failed to register iommu
  arm-smmu-v3 arm-smmu-v3.9.auto: probe with driver arm-smmu-v3 failed with error -22

Since SMMU driver had been already expecting a potential duplicated Stream
ID in arm_smmu_install_ste_for_dev(), change the arm_smmu_insert_master()
routine to ignore a duplicated ID from the fwspec->sids array as well.

Note: this has been failing the iommu_device_probe() since 2021, although a
recent iommu commit in v6.15-rc1 that moves iommu_device_probe() started to
fail the SMMU driver probe. Since nobody has cared about DMA Alias support,
leave that as it was but fix the fundamental iommu_device_probe() breakage.

Fixes: cdf315f907d4 ("iommu/arm-smmu-v3: Maintain a SID->device structure")
Cc: stable@vger.kernel.org
Suggested-by: Jason Gunthorpe <jgg@nvidia.com>
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Signed-off-by: Nicolin Chen <nicolinc@nvidia.com>
Link: https://lore.kernel.org/r/20250415185620.504299-1-nicolinc@nvidia.com
Signed-off-by: Will Deacon <will@kernel.org>

diff --git a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
index 5467f85dd4631a7391b8016f582d84ec360be81e..0826b6bdf327fdc0869c0762ad6b1d76006d8cb8 100644 (file)
--- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
+++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
@@ -3388,6 +3388,7 @@ static int arm_smmu_insert_master(struct arm_smmu_device *smmu,
        mutex_lock(&smmu->streams_mutex);
        for (i = 0; i < fwspec->num_ids; i++) {
                struct arm_smmu_stream *new_stream = &master->streams[i];
+               struct rb_node *existing;
                u32 sid = fwspec->ids[i];
 
                new_stream->id = sid;
@@ -3398,10 +3399,20 @@ static int arm_smmu_insert_master(struct arm_smmu_device *smmu,
                        break;
 
                /* Insert into SID tree */
-               if (rb_find_add(&new_stream->node, &smmu->streams,
-                               arm_smmu_streams_cmp_node)) {
-                       dev_warn(master->dev, "stream %u already in tree\n",
-                                sid);
+               existing = rb_find_add(&new_stream->node, &smmu->streams,
+                                      arm_smmu_streams_cmp_node);
+               if (existing) {
+                       struct arm_smmu_master *existing_master =
+                               rb_entry(existing, struct arm_smmu_stream, node)
+                                       ->master;
+
+                       /* Bridged PCI devices may end up with duplicated IDs */
+                       if (existing_master == master)
+                               continue;
+
+                       dev_warn(master->dev,
+                                "stream %u already in tree from dev %s\n", sid,
+                                dev_name(existing_master->dev));
                        ret = -EINVAL;
                        break;
                }