KVM: arm64: Fix ID register initialization for non-protected pKVM guests

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Summary

CVECVE-2026-23425
StatePUBLISHED
AssignerLinux
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-04-03 14:16:28 UTC
Updated2026-04-03 16:10:23 UTC
DescriptionIn the Linux kernel, the following vulnerability has been resolved: KVM: arm64: Fix ID register initialization for non-protected pKVM guests In protected mode, the hypervisor maintains a separate instance of the `kvm` structure for each VM. For non-protected VMs, this structure is initialized from the host's `kvm` state. Currently, `pkvm_init_features_from_host()` copies the `KVM_ARCH_FLAG_ID_REGS_INITIALIZED` flag from the host without the underlying `id_regs` data being initialized. This results in the hypervisor seeing the flag as set while the ID registers remain zeroed. Consequently, `kvm_has_feat()` checks at EL2 fail (return 0) for non-protected VMs. This breaks logic that relies on feature detection, such as `ctxt_has_tcrx()` for TCR2_EL1 support. As a result, certain system registers (e.g., TCR2_EL1, PIR_EL1, POR_EL1) are not saved/restored during the world switch, which could lead to state corruption. Fix this by explicitly copying the ID registers from the host `kvm` to the hypervisor `kvm` for non-protected VMs during initialization, since we trust the host with its non-protected guests' features. Also ensure `KVM_ARCH_FLAG_ID_REGS_INITIALIZED` is cleared initially in `pkvm_init_features_from_host` so that `vm_copy_id_regs` can properly initialize them and set the flag once done.

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Linux Linux affected 41d6028e28bd474298ff10409c292ec46cf43a90 bce3847f7c51b86332bf2e554c9e80ca3820f16c git Not specified
CNA Linux Linux affected 41d6028e28bd474298ff10409c292ec46cf43a90 858620655c1fbff05997e162fc7d83a3293d5142 git Not specified
CNA Linux Linux affected 41d6028e28bd474298ff10409c292ec46cf43a90 7e7c2cf0024d89443a7af52e09e47b1fe634ab17 git Not specified
CNA Linux Linux affected 6.14 Not specified
CNA Linux Linux unaffected 6.14 semver Not specified
CNA Linux Linux unaffected 6.18.17 6.18.* semver Not specified
CNA Linux Linux unaffected 6.19.7 6.19.* semver Not specified
CNA Linux Linux unaffected 7.0-rc2 * original_commit_for_fix Not specified

References

ReferenceSourceLinkTags
git.kernel.org/stable/c/bce3847f7c51b86332bf2e554c9e80ca3820f16c 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/858620655c1fbff05997e162fc7d83a3293d5142 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/7e7c2cf0024d89443a7af52e09e47b1fe634ab17 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
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