[PATCH v1 13/13] arm64: mm: Provide level hint for flush_tlb_page()

Ryan Roberts
2025-12-16T14:46:34Z

Previously tlb invalidations issued by __flush_tlb_page() did not
contain a level hint. But the function is clearly only ever targeting
level 3 tlb entries and its documentation agrees:

| this operation only invalidates a single, last-level page-table
| entry and therefore does not affect any walk-caches

However, it turns out that the function was actually being used to
invalidate a level 2 mapping via flush_tlb_fix_spurious_fault_pmd(). The
bug was benign because the level hint was not set so the HW would still
invalidate the PMD mapping, and also because the TLBF_NONOTIFY flag was
set, the bounds of the mapping were never used for anything else.

Now that we have the new and improved range-invalidation API, it is
trival to fix flush_tlb_fix_spurious_fault_pmd() to explicitly flush the
whole range (locally, without notification and last level only). So
let's do that, and then update __flush_tlb_page() to hint level 3.

Signed-off-by: Ryan Roberts <ryan.roberts@arm.com>
---
arch/arm64/include/asm/pgtable.h | 5 +++--
arch/arm64/include/asm/tlbflush.h | 2 +-
2 files changed, 4 insertions(+), 3 deletions(-)

diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/pgtable.h
index b96a7ca465a1..61f57647361a 100644
--- a/arch/arm64/include/asm/pgtable.h
+++ b/arch/arm64/include/asm/pgtable.h
@@ -138,8 +138,9 @@ static inline void arch_leave_lazy_mmu_mode(void)
#define flush_tlb_fix_spurious_fault(vma, address, ptep) \
__flush_tlb_page(vma, address, TLBF_NOBROADCAST | TLBF_NONOTIFY)

-#define flush_tlb_fix_spurious_fault_pmd(vma, address, pmdp) \
- __flush_tlb_page(vma, address, TLBF_NOBROADCAST | TLBF_NONOTIFY)
+#define flush_tlb_fix_spurious_fault_pmd(vma, address, pmdp) \
+ __flush_tlb_range(vma, address, address + PMD_SIZE, PMD_SIZE, 2, \
+ TLBF_NOBROADCAST | TLBF_NONOTIFY | TLBF_NOWALKCACHE)

/*
* ZERO_PAGE is a global shared page that is always zero: used
diff --git a/arch/arm64/include/asm/tlbflush.h b/arch/arm64/include/asm/tlbflush.h
index fa5aee990742..f24211b51df3 100644
--- a/arch/arm64/include/asm/tlbflush.h
+++ b/arch/arm64/include/asm/tlbflush.h
@@ -577,7 +577,7 @@ static inline void __flush_tlb_page(struct vm_area_struct *vma,
unsigned long start = round_down(uaddr, PAGE_SIZE);
unsigned long end = start + PAGE_SIZE;

- ___flush_tlb_range(vma, start, end, PAGE_SIZE, TLBI_TTL_UNKNOWN,
+ ___flush_tlb_range(vma, start, end, PAGE_SIZE, 3,
TLBF_NOWALKCACHE | flags);
}

--
2.43.0