[PATCH v8 5/6] KVM: arm64: Reuse fields of sys_reg_desc for idreg

[Jing Zhang]

Hi Cornelia,


On Tue, May 16, 2023 at 3:26 AM Cornelia Huck <cohuck at redhat.com> wrote:
>
> On Wed, May 03 2023, Jing Zhang <jingzhangos at google.com> wrote:
>
> > Since reset() and val are not used for idreg in sys_reg_desc, they would
> > be used with other purposes for idregs.
> > The callback reset() would be used to return KVM sanitised id register
> > values. The u64 val would be used as mask for writable fields in idregs.
> > Only bits with 1 in val are writable from userspace.
> >
> > Signed-off-by: Jing Zhang <jingzhangos at google.com>
> > ---
> >  arch/arm64/kvm/id_regs.c  | 44 +++++++++++++++++++----------
> >  arch/arm64/kvm/sys_regs.c | 59 +++++++++++++++++++++++++++------------
> >  arch/arm64/kvm/sys_regs.h | 10 ++++---
> >  3 files changed, 77 insertions(+), 36 deletions(-)
> >
>
> (...)
>
> > diff --git a/arch/arm64/kvm/sys_regs.h b/arch/arm64/kvm/sys_regs.h
> > index e88fd77309b2..21869319f6e1 100644
> > --- a/arch/arm64/kvm/sys_regs.h
> > +++ b/arch/arm64/kvm/sys_regs.h
> > @@ -65,12 +65,12 @@ struct sys_reg_desc {
> >                      const struct sys_reg_desc *);
> >
> >       /* Initialization for vcpu. */
>
> Maybe be a bit more verbose here?
>
> /* Initialization for vcpu. Return initialized value, or KVM sanitized
>    value for id registers. */
Sure. Thanks.
>
> > -     void (*reset)(struct kvm_vcpu *, const struct sys_reg_desc *);
> > +     u64 (*reset)(struct kvm_vcpu *, const struct sys_reg_desc *);
> >
> >       /* Index into sys_reg[], or 0 if we don't need to save it. */
> >       int reg;
> >
> > -     /* Value (usually reset value) */
> > +     /* Value (usually reset value), or write mask for idregs */
> >       u64 val;
> >
> >       /* Custom get/set_user functions, fallback to generic if NULL */
>
Jing