On Wed, Dec 04 2024 at 18:25, Frank Li wrote: > Some MSI controller change address/data pair when irq_set_affinity(). > Current PCI endpoint can't support this type MSI controller. So add flag > MSI_FLAG_MUTABLE in include/linux/msi.h and check it when allocate > doorbell. Q: Who is going to annotate the affected domains with that flag? A: Nobody. Q: What's the value of the flag? A: Zero, as as it prevents exactly nothing. You want a MSI_FLAG_MSG_IMMUTABLE and set that on the domains which provide it. That way you ensure that someone looked at the domain to validate it. Thanks, tglx