On Mon, Nov 30, 2020 at 08:18:45PM +0800, Yanan Wang wrote: > When installing a new leaf pte onto an invalid ptep, we need to > get_page(ptep). > When just updating a valid leaf ptep, we shouldn't get_page(ptep). > Incorrect page_count of translation tables might lead to memory leak, > when unmapping a stage 2 memory range.
Did you find this by inspection, or did you hit this in practice? I'd be interested to see the backtrace for mapping over an existing mapping. > Signed-off-by: Yanan Wang <wangyana...@huawei.com> > --- > arch/arm64/kvm/hyp/pgtable.c | 7 ++++--- > 1 file changed, 4 insertions(+), 3 deletions(-) > > diff --git a/arch/arm64/kvm/hyp/pgtable.c b/arch/arm64/kvm/hyp/pgtable.c > index 0271b4a3b9fe..696b6aa83faf 100644 > --- a/arch/arm64/kvm/hyp/pgtable.c > +++ b/arch/arm64/kvm/hyp/pgtable.c > @@ -186,6 +186,7 @@ static bool kvm_set_valid_leaf_pte(kvm_pte_t *ptep, u64 > pa, kvm_pte_t attr, > return old == pte; > > smp_store_release(ptep, pte); > + get_page(virt_to_page(ptep)); This is also used for the hypervisor stage-1 page-table, so I'd prefer to leave this function as-is. > return true; > } > > @@ -476,6 +477,7 @@ static bool stage2_map_walker_try_leaf(u64 addr, u64 end, > u32 level, > /* There's an existing valid leaf entry, so perform break-before-make */ > kvm_set_invalid_pte(ptep); > kvm_call_hyp(__kvm_tlb_flush_vmid_ipa, data->mmu, addr, level); > + put_page(virt_to_page(ptep)); > kvm_set_valid_leaf_pte(ptep, phys, data->attr, level); > out: > data->phys += granule; Isn't this hunk alone sufficient to solve the problem? Will
