On Wed, Mar 03, 2021 at 10:42:25AM +0800, Jia He wrote: > If the start addr is not aligned with the granule size of that level. > loop step size should be adjusted to boundary instead of simple > kvm_granual_size(level) increment. Otherwise, some mmu entries might miss > the chance to be walked through. > E.g. Assume the unmap range [data->addr, data->end] is > [0xff00ab2000,0xff00cb2000] in level 2 walking and NOT block mapping. > And the 1st part of that pmd entry is [0xff00ab2000,0xff00c00000]. The > pmd value is 0x83fbd2c1002 (not valid entry). In this case, data->addr > should be adjusted to 0xff00c00000 instead of 0xff00cb2000. > > Without this fix, userspace "segment fault" error can be easily > triggered by running simple gVisor runsc cases on an Ampere Altra > server: > docker run --runtime=runsc -it --rm ubuntu /bin/bash > > In container: > for i in `seq 1 100`;do ls;done > > Reported-by: Howard Zhang <howard.zh...@arm.com> > Signed-off-by: Jia He <justin...@arm.com> > --- > arch/arm64/kvm/hyp/pgtable.c | 1 + > 1 file changed, 1 insertion(+) > > diff --git a/arch/arm64/kvm/hyp/pgtable.c b/arch/arm64/kvm/hyp/pgtable.c > index bdf8e55ed308..4d99d07c610c 100644 > --- a/arch/arm64/kvm/hyp/pgtable.c > +++ b/arch/arm64/kvm/hyp/pgtable.c > @@ -225,6 +225,7 @@ static inline int __kvm_pgtable_visit(struct > kvm_pgtable_walk_data *data, > goto out; > > if (!table) { > + data->addr = ALIGN_DOWN(data->addr, kvm_granule_size(level)); > data->addr += kvm_granule_size(level);
Can you replace both of these lines with: data->addr = ALIGN(data->addr, kvm_granule_size(level)); instead? Will