Re: [PATCH 05/14] KVM: arm64/sve: Clean up UAPI register ID definitions

[Dave Martin <Dave.Martin@arm.com>]

On Mon, Apr 15, 2019 at 05:17:39PM +0200, Andrew Jones wrote:
> On Fri, Apr 12, 2019 at 05:28:09PM +0100, Dave Martin wrote:
> > Currently, the SVE register ID macros are not all defined in the
> > same way, and advertise the fact that FFR maps onto the nonexistent
> > predicate register P16.  This is really just for kernel
> > convenience, and may lead userspace into bad habits.
> > 
> > Instead, this patch masks the ID macro arguments so that
> > architecturally invalid register numbers will not be passed through
> > any more, and uses a literal KVM_REG_ARM64_SVE_FFR_BASE macro to
> > define KVM_REG_ARM64_SVE_FFR(), similarly to the way the _ZREG()
> > and _PREG() macros are defined.
> > 
> > Rather than plugging in magic numbers for the number of Z- and P-
> > registers and the maximum possible number of register slices, this
> > patch provides definitions for those too.  Userspace is going to
> > need them in any case, and it makes sense for them to come from
> > <uapi/asm/kvm.h>.
> > 
> > sve_reg_to_region() uses convenience constants that are defined in
> > a different way, and also makes use of the fact that the FFR IDs
> > are really contiguous with the P15 IDs, so this patch retains the
> > existing convenience constants in guest.c, supplemented with a
> > couple of sanity checks to check for consistency with with the UAPI
> 
> s/with with/with/

Good spot, thanks.

> > header.
> > 
> > Fixes: e1c9c98345b3 ("KVM: arm64/sve: Add SVE support to register access ioctl interface")
> > Suggested-by: Andrew Jones <drjones@redhat.com>
> > Signed-off-by: Dave Martin <Dave.Martin@arm.com>
> > ---
> >  arch/arm64/include/uapi/asm/kvm.h | 32 +++++++++++++++++++++++---------
> >  arch/arm64/kvm/guest.c            |  9 +++++++++
> >  2 files changed, 32 insertions(+), 9 deletions(-)
> >
> 
> Reviewed-by: Andrew Jones <drjones@redhat.com>

Thanks
---Dave