| Message ID | 20210729132818.4091769-10-qperret@google.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | Track shared pages at EL2 in protected mode | expand |
Hi Quentin, On Thu, Jul 29, 2021 at 3:28 PM Quentin Perret <qperret@google.com> wrote: > > The current hypervisor stage-1 mapping code doesn't allow changing an > existing valid mapping. Relax this condition by allowing changes that > only target software bits, as that will soon be needed to annotate shared > pages. > > Signed-off-by: Quentin Perret <qperret@google.com> > --- > arch/arm64/kvm/hyp/pgtable.c | 18 ++++++++++++++++-- > 1 file changed, 16 insertions(+), 2 deletions(-) > > diff --git a/arch/arm64/kvm/hyp/pgtable.c b/arch/arm64/kvm/hyp/pgtable.c > index 1ee1168ac32d..2689fcb7901d 100644 > --- a/arch/arm64/kvm/hyp/pgtable.c > +++ b/arch/arm64/kvm/hyp/pgtable.c > @@ -362,6 +362,21 @@ static int hyp_set_prot_attr(enum kvm_pgtable_prot prot, kvm_pte_t *ptep) > return 0; > } > > +static bool hyp_pte_needs_update(kvm_pte_t old, kvm_pte_t new) > +{ > + /* > + * Tolerate KVM recreating the exact same mapping, or changing software > + * bits if the existing mapping was valid. > + */ > + if (old == new) > + return false; The added comment clarifies the rationale here. Thanks. Reviewed-by: Fuad Tabba <tabba@google.com> /fuad /fuad > + if (!kvm_pte_valid(old)) > + return true; > + > + return !WARN_ON((old ^ new) & ~KVM_PTE_LEAF_ATTR_HI_SW); > +} > + > static bool hyp_map_walker_try_leaf(u64 addr, u64 end, u32 level, > kvm_pte_t *ptep, struct hyp_map_data *data) > { > @@ -371,9 +386,8 @@ static bool hyp_map_walker_try_leaf(u64 addr, u64 end, u32 level, > if (!kvm_block_mapping_supported(addr, end, phys, level)) > return false; > > - /* Tolerate KVM recreating the exact same mapping */ > new = kvm_init_valid_leaf_pte(phys, data->attr, level); > - if (old != new && !WARN_ON(kvm_pte_valid(old))) > + if (hyp_pte_needs_update(old, new)) > smp_store_release(ptep, new); > > data->phys += granule; > -- > 2.32.0.432.gabb21c7263-goog >
diff --git a/arch/arm64/kvm/hyp/pgtable.c b/arch/arm64/kvm/hyp/pgtable.c index 1ee1168ac32d..2689fcb7901d 100644 --- a/arch/arm64/kvm/hyp/pgtable.c +++ b/arch/arm64/kvm/hyp/pgtable.c @@ -362,6 +362,21 @@ static int hyp_set_prot_attr(enum kvm_pgtable_prot prot, kvm_pte_t *ptep) return 0; } +static bool hyp_pte_needs_update(kvm_pte_t old, kvm_pte_t new) +{ + /* + * Tolerate KVM recreating the exact same mapping, or changing software + * bits if the existing mapping was valid. + */ + if (old == new) + return false; + + if (!kvm_pte_valid(old)) + return true; + + return !WARN_ON((old ^ new) & ~KVM_PTE_LEAF_ATTR_HI_SW); +} + static bool hyp_map_walker_try_leaf(u64 addr, u64 end, u32 level, kvm_pte_t *ptep, struct hyp_map_data *data) { @@ -371,9 +386,8 @@ static bool hyp_map_walker_try_leaf(u64 addr, u64 end, u32 level, if (!kvm_block_mapping_supported(addr, end, phys, level)) return false; - /* Tolerate KVM recreating the exact same mapping */ new = kvm_init_valid_leaf_pte(phys, data->attr, level); - if (old != new && !WARN_ON(kvm_pte_valid(old))) + if (hyp_pte_needs_update(old, new)) smp_store_release(ptep, new); data->phys += granule;
The current hypervisor stage-1 mapping code doesn't allow changing an existing valid mapping. Relax this condition by allowing changes that only target software bits, as that will soon be needed to annotate shared pages. Signed-off-by: Quentin Perret <qperret@google.com> --- arch/arm64/kvm/hyp/pgtable.c | 18 ++++++++++++++++-- 1 file changed, 16 insertions(+), 2 deletions(-)