From: Will Deacon <will@xxxxxxxxxx>
commit f62d4c3eb687d87b616b4279acec7862553bda77 upstream.
Commit 7657ea920c54 ("KVM: arm64: Use TLBI range-based instructions for
unmap") introduced deferred TLB invalidation for the stage-2 page-table
so that range-based invalidation can be used for the accumulated
addresses. This works fine if the structure of the page-tables remains
unchanged, but if entire tables are zapped and subsequently freed then
we transiently leave the hardware page-table walker with a reference
to freed memory thanks to the translation walk caches. For example,
stage2_unmap_walker() will free page-table pages:
if (childp)
mm_ops->put_page(childp);
and issue the TLB invalidation later in kvm_pgtable_stage2_unmap():
if (stage2_unmap_defer_tlb_flush(pgt))
/* Perform the deferred TLB invalidations */
kvm_tlb_flush_vmid_range(pgt->mmu, addr, size);
For now, take the conservative approach and invalidate the TLB eagerly
when we clear a table entry. Note, however, that the existing level
hint passed to __kvm_tlb_flush_vmid_ipa() is incorrect and will be
fixed in a subsequent patch.
Cc: Raghavendra Rao Ananta <rananta@xxxxxxxxxx>
Cc: Shaoqin Huang <shahuang@xxxxxxxxxx>
Cc: Marc Zyngier <maz@xxxxxxxxxx>
Cc: Oliver Upton <oliver.upton@xxxxxxxxx>
Reviewed-by: Shaoqin Huang <shahuang@xxxxxxxxxx>
Reviewed-by: Marc Zyngier <maz@xxxxxxxxxx>
Link: https://lore.kernel.org/r/20240327124853.11206-2-will@xxxxxxxxxx
Signed-off-by: Oliver Upton <oliver.upton@xxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx> # 6.6.y only
Signed-off-by: Will Deacon <will@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
arch/arm64/kvm/hyp/pgtable.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
--- a/arch/arm64/kvm/hyp/pgtable.c
+++ b/arch/arm64/kvm/hyp/pgtable.c
@@ -861,9 +861,11 @@ static void stage2_unmap_put_pte(const s
if (kvm_pte_valid(ctx->old)) {
kvm_clear_pte(ctx->ptep);
- if (!stage2_unmap_defer_tlb_flush(pgt))
+ if (!stage2_unmap_defer_tlb_flush(pgt) ||
+ kvm_pte_table(ctx->old, ctx->level)) {
kvm_call_hyp(__kvm_tlb_flush_vmid_ipa, mmu,
ctx->addr, ctx->level);
+ }
}
mm_ops->put_page(ctx->ptep);
Patches currently in stable-queue which might be from will@xxxxxxxxxx are
queue-6.6/kvm-arm64-don-t-defer-tlb-invalidation-when-zapping-table-entries.patch
queue-6.6/kvm-arm64-don-t-pass-a-tlbi-level-hint-when-zapping-table-entries.patch
