Re: [Qemu-devel] [PATCH 05/13] target/arm/kvm: Add kvm_arch_get/put_sve

[Andrew Jones]

On Mon, May 13, 2019 at 01:43:56PM +0100, Dave Martin wrote:
> On Sun, May 12, 2019 at 09:36:16AM +0100, Andrew Jones wrote:
> > These are the SVE equivalents to kvm_arch_get/put_fpsimd.
> > 
> > Signed-off-by: Andrew Jones <address@hidden>
> > ---
> >  target/arm/kvm64.c | 127 +++++++++++++++++++++++++++++++++++++++++++--
> >  1 file changed, 123 insertions(+), 4 deletions(-)
> 
> [...]
> 
> > +static int kvm_arch_put_sve(CPUState *cs)
> > +{
> > +    ARMCPU *cpu = ARM_CPU(cs);
> > +    CPUARMState *env = &cpu->env;
> > +    struct kvm_one_reg reg;
> > +    int n, ret;
> > +
> > +    for (n = 0; n < KVM_ARM64_SVE_NUM_ZREGS; n++) {
> > +        uint64_t *q = aa64_vfp_qreg(env, n);
> > +#ifdef HOST_WORDS_BIGENDIAN
> > +        uint64_t d[ARM_MAX_VQ * 2];
> > +        int i;
> > +        for (i = 0; i < cpu->sve_max_vq * 2; i++) {
> > +            d[i] = q[cpu->sve_max_vq * 2 - 1 - i];
> > +        }
> > +        reg.addr = (uintptr_t)d;
> > +#else
> > +        reg.addr = (uintptr_t)q;
> > +#endif
> > +        reg.id = KVM_REG_ARM64_SVE_ZREG(n, 0);
> 
> Will this silently go wrong if more than one slice is required (i.e.,
> the register size grows beyond 8192 bits?)

Yeah, I could probably implement the slice loop now and add a
function that returns 1 (for now) like your vcpu_sve_slices()
function in KVM. I'll do that for v2.

Thanks,
drew



> 
> [...]
> 
> Cheers
> ---Dave
>