I'm running a 32-bit linux kernel and I think that's the problem. The ECAM address base is at 0x4010000000, but it gets truncated to 0x10000000 because it's only a 32-bit kernel, but since it's truncated, it conflicts with VIRT_PCIE_MMIO (see hw/arm/virt.c) whose range is from 0x10000000 to 0x3efeffff which matches what we see in the error message.
I tried to triage this a bit today.
I'm running a 32-bit linux kernel and I think that's the problem. The ECAM address base is at 0x4010000000, but it gets truncated to 0x10000000 because it's only a 32-bit kernel, but since it's truncated, it conflicts with VIRT_PCIE_MMIO (see hw/arm/virt.c) whose range is from 0x10000000 to 0x3efeffff which matches what we see in the error message.