CVE-2025-38560

In the Linux kernel, the following vulnerability has been resolved:<br /> <br /> x86/sev: Evict cache lines during SNP memory validation<br /> <br /> An SNP cache coherency vulnerability requires a cache line eviction<br /> mitigation when validating memory after a page state change to private.<br /> The specific mitigation is to touch the first and last byte of each 4K<br /> page that is being validated. There is no need to perform the mitigation<br /> when performing a page state change to shared and rescinding validation.<br /> <br /> CPUID bit Fn8000001F_EBX[31] defines the COHERENCY_SFW_NO CPUID bit<br /> that, when set, indicates that the software mitigation for this<br /> vulnerability is not needed.<br /> <br /> Implement the mitigation and invoke it when validating memory (making it<br /> private) and the COHERENCY_SFW_NO bit is not set, indicating the SNP<br /> guest is vulnerable.