Hi Dave,
On 19/03/2019 17:52, Dave Martin wrote:
> This patch includes the SVE register IDs in the list returned by
> KVM_GET_REG_LIST, as appropriate.
>
> On a non-SVE-enabled vcpu, no new IDs are added.
>
> On an SVE-enabled vcpu, IDs for the FPSIMD V-registers are removed
> from the list, since userspace is required to access the Z-
> registers instead in order to access the V-register content. For
> the variably-sized SVE registers, the appropriate set of slice IDs
> are enumerated, depending on the maximum vector length for the
> vcpu.
>
> As it currently stands, the SVE architecture never requires more
> than one slice to exist per register, so this patch adds no
> explicit support for enumerating multiple slices. The code can be
> extended straightforwardly to support this in the future, if
> needed.
>
> Signed-off-by: Dave Martin <Dave.Martin@xxxxxxx>
>
Reviewed-by: Julien Thierry <julien.thierry@xxxxxxx>
> ---
>
> Changes since v5:
>
> (Dropped Julien Thierry's Reviewed-by due to non-trivial rebasing)
>
> * Move mis-split reword to prevent put_user()s being accidentally the
> correct size from KVM: arm64/sve: Add pseudo-register for the guest's
> vector lengths.
> ---
> arch/arm64/kvm/guest.c | 56 ++++++++++++++++++++++++++++++++++++++++++++++++++
> 1 file changed, 56 insertions(+)
>
> diff --git a/arch/arm64/kvm/guest.c b/arch/arm64/kvm/guest.c
> index 736d8cb..585c31e5 100644
> --- a/arch/arm64/kvm/guest.c
> +++ b/arch/arm64/kvm/guest.c
> @@ -411,6 +411,56 @@ static int get_timer_reg(struct kvm_vcpu *vcpu, const struct kvm_one_reg *reg)
> return copy_to_user(uaddr, &val, KVM_REG_SIZE(reg->id)) ? -EFAULT : 0;
> }
>
> +static unsigned long num_sve_regs(const struct kvm_vcpu *vcpu)
> +{
> + /* Only the first slice ever exists, for now */
> + const unsigned int slices = 1;
Nit: Might be worth introducing a macro/inline function for the number
of slices supported. This way, the day we need to change that, we only
need to look for that identifier.
Cheers,
--
Julien Thierry
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