The patch below does not apply to the 6.6-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.6.y git checkout FETCH_HEAD git cherry-pick -x b00d24997a11c10d3e420614f0873b83ce358a34 # <resolve conflicts, build, test, etc.> git commit -s git send-email --to 'stable@vger.kernel.org' --in-reply-to '2025050520-chastity-tasty-6f1e@gregkh' --subject-prefix 'PATCH 6.6.y' HEAD^..

Possible dependencies:

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From b00d24997a11c10d3e420614f0873b83ce358a34 Mon Sep 17 00:00:00 2001 From: Nicolin Chen nicolinc@nvidia.com Date: Tue, 15 Apr 2025 11:56:20 -0700 Subject: [PATCH] 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 5467f85dd463..0826b6bdf327 100644 --- 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; }