Re: [RFC PATCH v2 23/23] KVM: arm64/sve: Document KVM API extensions for SVE

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

On Thu, Nov 22, 2018 at 03:31:51PM +0000, Alex Bennée wrote:
> 
> Dave Martin <Dave.Martin@arm.com> writes:
> 
> > This patch adds sections to the KVM API documentation describing
> > the extensions for supporting the Scalable Vector Extension (SVE)
> > in guests.
> >
> > Signed-off-by: Dave Martin <Dave.Martin@arm.com>
> > ---
> >  Documentation/virtual/kvm/api.txt | 142 +++++++++++++++++++++++++++++++++++++-
> >  1 file changed, 139 insertions(+), 3 deletions(-)
> >
> > diff --git a/Documentation/virtual/kvm/api.txt b/Documentation/virtual/kvm/api.txt
> > index a58067b..b8257d4 100644
> > --- a/Documentation/virtual/kvm/api.txt
> > +++ b/Documentation/virtual/kvm/api.txt
> > @@ -2054,13 +2054,21 @@ Specifically:
> >    0x6030 0000 0010 004c SPSR_UND    64  spsr[KVM_SPSR_UND]
> >    0x6030 0000 0010 004e SPSR_IRQ    64  spsr[KVM_SPSR_IRQ]
> >    0x6060 0000 0010 0050 SPSR_FIQ    64  spsr[KVM_SPSR_FIQ]
> > -  0x6040 0000 0010 0054 V0         128  fp_regs.vregs[0]
> > -  0x6040 0000 0010 0058 V1         128  fp_regs.vregs[1]
> > +  0x6040 0000 0010 0054 V0         128  fp_regs.vregs[0]    (*)
> > +  0x6040 0000 0010 0058 V1         128  fp_regs.vregs[1]    (*)
> >      ...
> > -  0x6040 0000 0010 00d0 V31        128  fp_regs.vregs[31]
> > +  0x6040 0000 0010 00d0 V31        128  fp_regs.vregs[31]   (*)
> >    0x6020 0000 0010 00d4 FPSR        32  fp_regs.fpsr
> >    0x6020 0000 0010 00d5 FPCR        32  fp_regs.fpcr
> >
> > +(*) These encodings are not accepted for SVE-enabled vcpus.  See
> > +    KVM_ARM_SVE_CONFIG for details of how SVE support is configured for
> > +    a vcpu.
> > +
> > +    The equivalent register content can be accessed via bits [2047:0]
> > of
> 
> You mean [127:0] I think.

Good spot.  Yes.

Possibly I meant "through the first slice of the corresponding Zn",
though [127:0] should make it clear both which slice and which bits
within the slice to look at.

[...]

Cheers
---Dave