Linux Kernel PCI/MSI Vulnerability Handling in RISC-V and Loongarch Platforms

A vulnerability in the Linux kernel's PCI/MSI handling has been addressed, specifically for RISC-V and Loongarch platforms that lack proper PCI/MSI support. The issue arose because these platforms enabled legacy support without implementing the necessary fallbacks, leading to warnings during the MSI IRQ setup process. The vulnerability has been resolved by correcting the evaluation of legacy mode support and adding the missing checks in the MSI enable path.

Impact

The vulnerability could cause unnecessary warnings during the PCI/MSI IRQ setup on platforms that do not support it, potentially leading to confusion or misinterpretation of the system's interrupt handling capabilities.