Commit a75b2be249d6 ("iommu: Add iommu_driver_get_domain_for_dev()
helper") introduced iommu_driver_get_domain_for_dev() for driver
code paths that hold iommu_group->mutex while attaching a device
to an IOMMU domain.The same commit also added a lockdep assertion in iommu_get_domain_for_dev() to ensure that callers do not hold iommu_group->mutex when invoking it. On powerpc platforms, when PCI device ownership is switched from BLOCKED to the PLATFORM domain, the attach callback spapr_tce_platform_iommu_attach_dev() still calls iommu_get_domain_for_dev(). This happens while iommu_group->mutex is held during domain switching, which triggers the lockdep warning below during PCI enumeration: WARNING: drivers/iommu/iommu.c:2252 at iommu_get_domain_for_dev+0x38/0x80, CPU#2: swapper/0/1 Modules linked in: CPU: 2 UID: 0 PID: 1 Comm: swapper/0 Not tainted 7.0.0-rc2+ #35 PREEMPT Hardware name: IBM,9105-22A Power11 (architected) 0x820200 0xf000007 of:IBM,FW1120.00 (RB1120_115) hv:phyp pSeries NIP: c000000000c244c4 LR: c00000000005b5a4 CTR: c00000000005b578 REGS: c00000000a7bf280 TRAP: 0700 Not tainted (7.0.0-rc2+) MSR: 8000000002029033 <SF,VEC,EE,ME,IR,DR,RI,LE> CR: 22004422 XER: 0000000a CFAR: c000000000c24508 IRQMASK: 0 GPR00: c00000000005b5a4 c00000000a7bf520 c000000001dc8100 0000000000000001 GPR04: c00000000f972f10 0000000000000000 0000000000000000 0000000000000001 GPR08: 0000001ffbc60000 0000000000000001 0000000000000000 0000000000000000 GPR12: c00000000005b578 c000001fffffe480 c000000000011618 0000000000000000 GPR16: 0000000000000000 0000000000000000 0000000000000000 0000000000000000 GPR20: ffffffffffffefff 0000000000000000 c000000002d30eb0 0000000000000001 GPR24: c0000000017881f8 0000000000000000 0000000000000001 c00000000f972e00 GPR28: c00000000bbba0d0 0000000000000000 c00000000bbba0d0 c00000000f972e00 NIP [c000000000c244c4] iommu_get_domain_for_dev+0x38/0x80 LR [c00000000005b5a4] spapr_tce_platform_iommu_attach_dev+0x2c/0x98 Call Trace: iommu_get_domain_for_dev+0x68/0x80 (unreliable) spapr_tce_platform_iommu_attach_dev+0x2c/0x98 __iommu_attach_device+0x44/0x220 __iommu_device_set_domain+0xf4/0x194 __iommu_group_set_domain_internal+0xec/0x228 iommu_setup_default_domain+0x5f4/0x6a4 __iommu_probe_device+0x674/0x724 iommu_probe_device+0x50/0xb4 iommu_add_device+0x48/0x198 pci_dma_dev_setup_pSeriesLP+0x198/0x4f0 pcibios_bus_add_device+0x80/0x464 pci_bus_add_device+0x40/0x100 pci_bus_add_devices+0x54/0xb0 pcibios_init+0xd8/0x140 do_one_initcall+0x8c/0x598 kernel_init_freeable+0x3ec/0x850 kernel_init+0x34/0x270 ret_from_kernel_user_thread+0x14/0x1c Fix this by using iommu_driver_get_domain_for_dev() instead of iommu_get_domain_for_dev() in spapr_tce_platform_iommu_attach_dev(), which is the appropriate helper for callers holding the group mutex. Cc: [email protected] Fixes: a75b2be249d6 ("iommu: Add iommu_driver_get_domain_for_dev() helper") Signed-off-by: Nilay Shroff <[email protected]> --- arch/powerpc/kernel/iommu.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/arch/powerpc/kernel/iommu.c b/arch/powerpc/kernel/iommu.c index 0ce71310b7d9..d122e8447831 100644 --- a/arch/powerpc/kernel/iommu.c +++ b/arch/powerpc/kernel/iommu.c @@ -1159,7 +1159,7 @@ spapr_tce_platform_iommu_attach_dev(struct iommu_domain *platform_domain, struct device *dev, struct iommu_domain *old) { - struct iommu_domain *domain = iommu_get_domain_for_dev(dev); + struct iommu_domain *domain = iommu_driver_get_domain_for_dev(dev); struct iommu_table_group *table_group; struct iommu_group *grp; -- 2.53.0
