On 7/7/2025 6:50 AM, Zhuo, Qiuxu wrote: > Is it possible for the "source_bitmap" to have some non-NMIS_NO_SOURCE bit > set > while the user registers their NMI handler with the NMIS_NO_SOURCE type? >
IIUC, this is what you are asking: Someone registers a handler without any source information. For example, GHES does this. register_nmi_handler(NMI_LOCAL, ghes_notify_nmi, 0, "ghes", NMIS_NO_SOURCE); Now, when a GHES NMI shows up, can it have anything other than bit 0 (NMIS_NO_SOURCE) set in the source bitmap? I believe the answer is no. Unless the GHES implementation or the hardware has a bug, this should not happen. If this happens, it would get logged as an unknown NMI in the kernel log. > If so, we may need to allow the NMI handler with the NMIS_NO_SOURCE type to > be > invoked unconditionally to ensure no NMIs are lost. > If the kernel can't rely on the accuracy of the source_bitmap, then NMI-source as a feature starts losing value. Sohil
