In the Linux kernel, the following vulnerability has been resolved: KVM: PPC: Book3S HV: fix secure device page leak on uv_page_in() failur

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

KVM: PPC: Book3S HV: fix secure device page leak on uv_page_in() failure

In kvmppc_svm_page_in(), if uv_page_in() fails after
kvmppc_uvmem_get_page() has succeeded, the secure device page is never
released. kvmppc_uvmem_get_page() sets a bit in kvmppc_uvmem_bitmap,
allocates a kvmppc_uvmem_page_pvt struct, marks the GFN as
KVMPPC_GFN_UVMEM_PFN, and calls zone_device_page_init() which sets
refcount=1 and locks the page. The subsequent goto out_finalize skips
the *mig.dst assignment, so migrate_vma_finalize() is a no-op for the
page, and none of those resources are ever reclaimed.

Each occurrence permanently consumes one entry from the firmware-bounded
secure memory pool (kvmppc_uvmem_bitmap), leaks pvt, and leaves the GFN
marked as secure — making it unusable for the lifetime of the VM.

The twin __kvmppc_svm_page_out() already handles the analogous uv_page_out()
failure correctly with unlock_page(dpage); __free_page(dpage). Apply
the same pattern here: unlock_page() followed by put_page(), which
chains through free_zone_device_folio() into kvmppc_uvmem_folio_free()
to clear the bitmap bit, free pvt, and reset the GFN state.

Reachable whenever uv_page_in() returns an error (e.g. UV pool
exhaustion) on any POWER9/10 + Ultravisor/PEF system.