coreboot

In dmesg, I get the following iommu event logs about INVALID_DEVICE_REQUEST:

[    3.651111] iommu ivhd0: Event logged [INVALID_DEVICE_REQUEST device=00:02.0 pasid=0x00000 address=0xfdf8210300 flags=0x0a00]
[    6.075105] iommu ivhd0: Event logged [INVALID_DEVICE_REQUEST device=00:04.0 pasid=0x00000 address=0xfdf8210400 flags=0x0a00]
[    6.075311] iommu ivhd0: Event logged [INVALID_DEVICE_REQUEST device=00:09.0 pasid=0x00000 address=0xfdf8210500 flags=0x0a00]
[    6.075492] iommu ivhd0: Event logged [INVALID_DEVICE_REQUEST device=00:0a.0 pasid=0x00000 address=0xfdf8210600 flags=0x0a00]
[    6.075665] iommu ivhd0: Event logged [INVALID_DEVICE_REQUEST device=00:0b.0 pasid=0x00000 address=0xfdf8210700 flags=0x0a00]

The 4 devices in question are (lspci):

00:02.0 PCI bridge: Advanced Micro Devices, Inc. [AMD/ATI] RD890/RD9x0/RX980 PCI to PCI bridge (PCI Express GFX port 0)
00:04.0 PCI bridge: Advanced Micro Devices, Inc. [AMD/ATI] RD890/RD9x0/RX980 PCI to PCI bridge (PCI Express GPP Port 0)
00:09.0 PCI bridge: Advanced Micro Devices, Inc. [AMD/ATI] RD890/RD9x0/RX980 PCI to PCI bridge (PCI Express GPP Port 4)
00:0a.0 PCI bridge: Advanced Micro Devices, Inc. [AMD/ATI] RD890/RD9x0/RX980 PCI to PCI bridge (PCI Express GPP Port 5)
00:0b.0 PCI bridge: Advanced Micro Devices, Inc. [AMD/ATI] RD890/RD990 PCI to PCI bridge (PCI Express GFX2 port 0)

In Coreboot's config, I noticed some option for an early PCI bridge; I wonder if that could be relevant in some way?

• This happens with or without CPU microcode being included in the ROM
• I haven't tested anything with iommu or virtualization to know if this is an actual problem
• If I build Coreboot and disable IOMMU from nvram (along with having it automatically not used from the Linux OS), there's no errors related to those PCI devices
• I attached a full dmesg and lspci dump