Memory Mapping Issue in Linux Kernel for KVM with Legacy PCI Devices

CVE-2025-40181

What is CVE-2025-40181?

A vulnerability present in the Linux Kernel affects the handling of memory mappings for legacy PCI devices when operating as a Secure Nested Paging (SNP) or Trusted Domain eXtension (TDX) guest under Kernel-based Virtual Machine (KVM). The issue arises when the kernel's Advanced Configuration and Power Interface (ACPI) driver maps SystemMemory regions with the wrong memory type, potentially causing device drivers, such as those for High Precision Event Timer (HPET) and Trusted Platform Module (TPM), to fail initialization due to incompatible cache settings. This inconsistency leads to issues when the requested memory type from the drivers doesn't match the type established by the ACPI mappings, ultimately resulting in operation failures.

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