| Message ID | 20221107215644.1895162-11-oliver.upton@linux.dev (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | KVM: arm64: Parallel stage-2 fault handling | expand |
On Mon, Nov 7, 2022 at 1:58 PM Oliver Upton <oliver.upton@linux.dev> wrote: > > Create a helper to initialize a table and directly call > smp_store_release() to install it (for now). Prepare for a subsequent > change that generalizes PTE writes with a helper. > > Signed-off-by: Oliver Upton <oliver.upton@linux.dev> > --- > arch/arm64/kvm/hyp/pgtable.c | 20 ++++++++++---------- > 1 file changed, 10 insertions(+), 10 deletions(-) > > diff --git a/arch/arm64/kvm/hyp/pgtable.c b/arch/arm64/kvm/hyp/pgtable.c > index a34e2050f931..f4dd77c6c97d 100644 > --- a/arch/arm64/kvm/hyp/pgtable.c > +++ b/arch/arm64/kvm/hyp/pgtable.c > @@ -136,16 +136,13 @@ static void kvm_clear_pte(kvm_pte_t *ptep) > WRITE_ONCE(*ptep, 0); > } > > -static void kvm_set_table_pte(kvm_pte_t *ptep, kvm_pte_t *childp, > - struct kvm_pgtable_mm_ops *mm_ops) > +static kvm_pte_t kvm_init_table_pte(kvm_pte_t *childp, struct kvm_pgtable_mm_ops *mm_ops) > { > - kvm_pte_t old = *ptep, pte = kvm_phys_to_pte(mm_ops->virt_to_phys(childp)); > + kvm_pte_t pte = kvm_phys_to_pte(mm_ops->virt_to_phys(childp)); > > pte |= FIELD_PREP(KVM_PTE_TYPE, KVM_PTE_TYPE_TABLE); > pte |= KVM_PTE_VALID; > - > - WARN_ON(kvm_pte_valid(old)); Is there any reason to drop this warning? > - smp_store_release(ptep, pte); > + return pte; > } > > static kvm_pte_t kvm_init_valid_leaf_pte(u64 pa, kvm_pte_t attr, u32 level) > @@ -413,7 +410,7 @@ static bool hyp_map_walker_try_leaf(const struct kvm_pgtable_visit_ctx *ctx, > static int hyp_map_walker(const struct kvm_pgtable_visit_ctx *ctx, > enum kvm_pgtable_walk_flags visit) > { > - kvm_pte_t *childp; > + kvm_pte_t *childp, new; > struct hyp_map_data *data = ctx->arg; > struct kvm_pgtable_mm_ops *mm_ops = ctx->mm_ops; > > @@ -427,8 +424,10 @@ static int hyp_map_walker(const struct kvm_pgtable_visit_ctx *ctx, > if (!childp) > return -ENOMEM; > > - kvm_set_table_pte(ctx->ptep, childp, mm_ops); > + new = kvm_init_table_pte(childp, mm_ops); > mm_ops->get_page(ctx->ptep); > + smp_store_release(ctx->ptep, new); > + > return 0; > } > > @@ -796,7 +795,7 @@ static int stage2_map_walk_leaf(const struct kvm_pgtable_visit_ctx *ctx, > struct stage2_map_data *data) > { > struct kvm_pgtable_mm_ops *mm_ops = ctx->mm_ops; > - kvm_pte_t *childp; > + kvm_pte_t *childp, new; > int ret; > > ret = stage2_map_walker_try_leaf(ctx, data); > @@ -821,8 +820,9 @@ static int stage2_map_walk_leaf(const struct kvm_pgtable_visit_ctx *ctx, > if (stage2_pte_is_counted(ctx->old)) > stage2_put_pte(ctx, data->mmu, mm_ops); > > - kvm_set_table_pte(ctx->ptep, childp, mm_ops); > + new = kvm_init_table_pte(childp, mm_ops); > mm_ops->get_page(ctx->ptep); > + smp_store_release(ctx->ptep, new); > > return 0; > } > -- > 2.38.1.431.g37b22c650d-goog >
On Wed, Nov 09, 2022 at 02:26:26PM -0800, Ben Gardon wrote: > On Mon, Nov 7, 2022 at 1:58 PM Oliver Upton <oliver.upton@linux.dev> wrote: > > > > Create a helper to initialize a table and directly call > > smp_store_release() to install it (for now). Prepare for a subsequent > > change that generalizes PTE writes with a helper. > > > > Signed-off-by: Oliver Upton <oliver.upton@linux.dev> > > --- > > arch/arm64/kvm/hyp/pgtable.c | 20 ++++++++++---------- > > 1 file changed, 10 insertions(+), 10 deletions(-) > > > > diff --git a/arch/arm64/kvm/hyp/pgtable.c b/arch/arm64/kvm/hyp/pgtable.c > > index a34e2050f931..f4dd77c6c97d 100644 > > --- a/arch/arm64/kvm/hyp/pgtable.c > > +++ b/arch/arm64/kvm/hyp/pgtable.c > > @@ -136,16 +136,13 @@ static void kvm_clear_pte(kvm_pte_t *ptep) > > WRITE_ONCE(*ptep, 0); > > } > > > > -static void kvm_set_table_pte(kvm_pte_t *ptep, kvm_pte_t *childp, > > - struct kvm_pgtable_mm_ops *mm_ops) > > +static kvm_pte_t kvm_init_table_pte(kvm_pte_t *childp, struct kvm_pgtable_mm_ops *mm_ops) > > { > > - kvm_pte_t old = *ptep, pte = kvm_phys_to_pte(mm_ops->virt_to_phys(childp)); > > + kvm_pte_t pte = kvm_phys_to_pte(mm_ops->virt_to_phys(childp)); > > > > pte |= FIELD_PREP(KVM_PTE_TYPE, KVM_PTE_TYPE_TABLE); > > pte |= KVM_PTE_VALID; > > - > > - WARN_ON(kvm_pte_valid(old)); > > Is there any reason to drop this warning? It is (eventually) superseded by a WARN() when a PTE isn't locked in stage2_make_pte(), but that isn't obvious in this patch alone. -- Thanks, Oliver
diff --git a/arch/arm64/kvm/hyp/pgtable.c b/arch/arm64/kvm/hyp/pgtable.c index a34e2050f931..f4dd77c6c97d 100644 --- a/arch/arm64/kvm/hyp/pgtable.c +++ b/arch/arm64/kvm/hyp/pgtable.c @@ -136,16 +136,13 @@ static void kvm_clear_pte(kvm_pte_t *ptep) WRITE_ONCE(*ptep, 0); } -static void kvm_set_table_pte(kvm_pte_t *ptep, kvm_pte_t *childp, - struct kvm_pgtable_mm_ops *mm_ops) +static kvm_pte_t kvm_init_table_pte(kvm_pte_t *childp, struct kvm_pgtable_mm_ops *mm_ops) { - kvm_pte_t old = *ptep, pte = kvm_phys_to_pte(mm_ops->virt_to_phys(childp)); + kvm_pte_t pte = kvm_phys_to_pte(mm_ops->virt_to_phys(childp)); pte |= FIELD_PREP(KVM_PTE_TYPE, KVM_PTE_TYPE_TABLE); pte |= KVM_PTE_VALID; - - WARN_ON(kvm_pte_valid(old)); - smp_store_release(ptep, pte); + return pte; } static kvm_pte_t kvm_init_valid_leaf_pte(u64 pa, kvm_pte_t attr, u32 level) @@ -413,7 +410,7 @@ static bool hyp_map_walker_try_leaf(const struct kvm_pgtable_visit_ctx *ctx, static int hyp_map_walker(const struct kvm_pgtable_visit_ctx *ctx, enum kvm_pgtable_walk_flags visit) { - kvm_pte_t *childp; + kvm_pte_t *childp, new; struct hyp_map_data *data = ctx->arg; struct kvm_pgtable_mm_ops *mm_ops = ctx->mm_ops; @@ -427,8 +424,10 @@ static int hyp_map_walker(const struct kvm_pgtable_visit_ctx *ctx, if (!childp) return -ENOMEM; - kvm_set_table_pte(ctx->ptep, childp, mm_ops); + new = kvm_init_table_pte(childp, mm_ops); mm_ops->get_page(ctx->ptep); + smp_store_release(ctx->ptep, new); + return 0; } @@ -796,7 +795,7 @@ static int stage2_map_walk_leaf(const struct kvm_pgtable_visit_ctx *ctx, struct stage2_map_data *data) { struct kvm_pgtable_mm_ops *mm_ops = ctx->mm_ops; - kvm_pte_t *childp; + kvm_pte_t *childp, new; int ret; ret = stage2_map_walker_try_leaf(ctx, data); @@ -821,8 +820,9 @@ static int stage2_map_walk_leaf(const struct kvm_pgtable_visit_ctx *ctx, if (stage2_pte_is_counted(ctx->old)) stage2_put_pte(ctx, data->mmu, mm_ops); - kvm_set_table_pte(ctx->ptep, childp, mm_ops); + new = kvm_init_table_pte(childp, mm_ops); mm_ops->get_page(ctx->ptep); + smp_store_release(ctx->ptep, new); return 0; }
Create a helper to initialize a table and directly call smp_store_release() to install it (for now). Prepare for a subsequent change that generalizes PTE writes with a helper. Signed-off-by: Oliver Upton <oliver.upton@linux.dev> --- arch/arm64/kvm/hyp/pgtable.c | 20 ++++++++++---------- 1 file changed, 10 insertions(+), 10 deletions(-)