x86/mm: Fix flush_tlb_range() when used for zapping normal PMDs

Vulnerability Description

In the Linux kernel, the following vulnerability has been resolved: x86/mm: Fix flush_tlb_range() when used for zapping normal PMDs On the following path, flush_tlb_range() can be used for zapping normal PMD entries (PMD entries that point to page tables) together with the PTE entries in the pointed-to page table: collapse_pte_mapped_thp pmdp_collapse_flush flush_tlb_range The arm64 version of flush_tlb_range() has a comment describing that it can be used for page table removal, and does not use any last-level invalidation optimizations. Fix the X86 version by making it behave the same way. Currently, X86 only uses this information for the following two purposes, which I think means the issue doesn't have much impact: - In native_flush_tlb_multi() for checking if lazy TLB CPUs need to be IPI'd to avoid issues with speculative page table walks. - In Hyper-V TLB paravirtualization, again for lazy TLB stuff. The patch "x86/mm: only invalidate final translations with INVLPGB" which is currently under review (see <https://lore.kernel.org/all/20241230175550.4046587-13-riel@surriel.com/>) would probably be making the impact of this a lot worse.

References

• https://git.kernel.org/stable/c/618d5612ecb7bfc1c85342daafeb2b47e29e77a3
• https://git.kernel.org/stable/c/556d446068f90981e5d71ca686bdaccdd545d491
• https://git.kernel.org/stable/c/0a8f806ea6b5dd64b3d1f05ff774817d5f7ddbd1
• https://git.kernel.org/stable/c/0708fd6bd8161871bfbadced2ca4319b84ab44fe
• https://git.kernel.org/stable/c/7085895c59e4057ffae17f58990ccb630087d0d2
• https://git.kernel.org/stable/c/93224deb50a8d20df3884f3672ce9f982129aa50
• https://git.kernel.org/stable/c/320ac1af4c0bdb92c864dc9250d1329234820edf
• https://git.kernel.org/stable/c/78d6f9a9eb2a5da6fcbd76d6191d24b0dcc321be
• https://git.kernel.org/stable/c/3ef938c3503563bfc2ac15083557f880d29c2e64