Hi Gavin,
On Thu, Nov 10, 2022 at 08:23:36AM +0800, Gavin Shan wrote:
> On 11/8/22 5:56 AM, Oliver Upton wrote:
> > Passing new arguments by value to the visitor callbacks is extremely
> > inflexible for stuffing new parameters used by only some of the
> > visitors. Use a context structure instead and pass the pointer through
> > to the visitor callback.
> >
> > While at it, redefine the 'flags' parameter to the visitor to contain
> > the bit indicating the phase of the walk. Pass the entire set of flags
> > through the context structure such that the walker can communicate
> > additional state to the visitor callback.
> >
> > No functional change intended.
> >
> > Signed-off-by: Oliver Upton <oliver.upton@xxxxxxxxx>
> > ---
> > arch/arm64/include/asm/kvm_pgtable.h | 15 +-
> > arch/arm64/kvm/hyp/nvhe/mem_protect.c | 10 +-
> > arch/arm64/kvm/hyp/nvhe/setup.c | 16 +-
> > arch/arm64/kvm/hyp/pgtable.c | 269 +++++++++++++-------------
> > 4 files changed, 154 insertions(+), 156 deletions(-)
> >
>
> Reviewed-by: Gavin Shan <gshan@xxxxxxxxxx>
>
> One nit below.
>
> > diff --git a/arch/arm64/include/asm/kvm_pgtable.h b/arch/arm64/include/asm/kvm_pgtable.h
> > index 3252eb50ecfe..607f9bb8aab4 100644
> > --- a/arch/arm64/include/asm/kvm_pgtable.h
> > +++ b/arch/arm64/include/asm/kvm_pgtable.h
> > @@ -199,10 +199,17 @@ enum kvm_pgtable_walk_flags {
> > KVM_PGTABLE_WALK_TABLE_POST = BIT(2),
> > };
> > -typedef int (*kvm_pgtable_visitor_fn_t)(u64 addr, u64 end, u32 level,
> > - kvm_pte_t *ptep,
> > - enum kvm_pgtable_walk_flags flag,
> > - void * const arg);
> > +struct kvm_pgtable_visit_ctx {
> > + kvm_pte_t *ptep;
> > + void *arg;
> > + u64 addr;
> > + u64 end;
> > + u32 level;
> > + enum kvm_pgtable_walk_flags flags;
> > +};
> > +
> > +typedef int (*kvm_pgtable_visitor_fn_t)(const struct kvm_pgtable_visit_ctx *ctx,
> > + enum kvm_pgtable_walk_flags visit);
>
> Does it make sense to reorder these fields in the context struct based on
> their properties.
The ordering was a deliberate optimization for space. Your suggestion
has 8 bytes of implicit padding:
> struct kvm_pgtable_visit_ctx {
> enum kvm_pgtable_walk_flags flags;
here
> u64 addr;
> u64 end;
> u32 level;
and here.
> kvm_pte_t *ptep;
> void *arg;
> };
--
Thanks,
Oliver
