commit 3ef938c3503563bfc2ac15083557f880d29c2e64 upstream.
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.
Fixes: 016c4d92cd ("x86/mm/tlb: Add freed_tables argument to flush_tlb_mm_range")
Signed-off-by: Jann Horn <jannh@google.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: stable@vger.kernel.org
Link: https://lkml.kernel.org/r/20250103-x86-collapse-flush-fix-v1-1-3c521856cfa6@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
0708fd6bd8