CVE-2026-72239

/// Technical description

In the Linux kernel, the following vulnerability has been resolved:

x86/virt/sev: Revert "Drop WBINVD before setting MSR_AMD64_SYSCFG_SNP_EN"

Revert

99cf1fb58e68 ("x86/virt/sev: Drop WBINVD before setting MSR_AMD64_SYSCFG_SNP_EN").

Section 8.8 of the SNP spec says:

Before invoking SNP_INIT_EX with INIT_RMP set to 1, software must ensure

that no CPUs contain dirty cache lines for the memory containing the RMP.

Cachelines can be moved from cache to cache in a dirty state. The

wbinvd_on_all_cpus() before SNP_INIT_EX flushes the caches for each CPU, but

if the IPIs for WBINVD race with this dirty cacheline movement, it is possible

that they may not get flushed, violating the firmware requirement.

Doing wbinvd_on_all_cpus() before setting SNPEn is safer since the RMP

table is not yet in use.

[ Heroically bisected by Srikanth. ]

[ bp: Massage commit message. ]

/// Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

/// References