From: Greg Kroah-Hartman <gregkh@xxxxxxxxxx>
Description
===========
In the Linux kernel, the following vulnerability has been resolved:
x86/sev: Do not touch VMSA pages during SNP guest memory kdump
When kdump is running makedumpfile to generate vmcore and dump SNP guest
memory it touches the VMSA page of the vCPU executing kdump.
It then results in unrecoverable #NPF/RMP faults as the VMSA page is
marked busy/in-use when the vCPU is running and subsequently a causes
guest softlockup/hang.
Additionally, other APs may be halted in guest mode and their VMSA pages
are marked busy and touching these VMSA pages during guest memory dump
will also cause #NPF.
Issue AP_DESTROY GHCB calls on other APs to ensure they are kicked out
of guest mode and then clear the VMSA bit on their VMSA pages.
If the vCPU running kdump is an AP, mark it's VMSA page as offline to
ensure that makedumpfile excludes that page while dumping guest memory.
The Linux kernel CVE team has assigned CVE-2025-38026 to this issue.
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