Re: [PATCH v7 09/27] KVM: arm64: Add a vcpu flag to control SVE visibility for the guest

Andrew Jones
2019-04-03T19:14:42Z

On Fri, Mar 29, 2019 at 01:00:34PM +0000, Dave Martin wrote:
> Since SVE will be enabled or disabled on a per-vcpu basis, a flag
> is needed in order to track which vcpus have it enabled.
>
> This patch adds a suitable flag and a helper for checking it.
>
> Signed-off-by: Dave Martin <Dave.Martin@arm.com>
> Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
> Tested-by: zhang.lei <zhang.lei@jp.fujitsu.com>
> ---
> arch/arm64/include/asm/kvm_host.h | 4 ++++
> 1 file changed, 4 insertions(+)
>
> diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
> index 6d10100..ad4f7f0 100644
> --- a/arch/arm64/include/asm/kvm_host.h
> +++ b/arch/arm64/include/asm/kvm_host.h
> @@ -328,6 +328,10 @@ struct kvm_vcpu_arch {
> #define KVM_ARM64_FP_HOST (1 << 2) /* host FP regs loaded */
> #define KVM_ARM64_HOST_SVE_IN_USE (1 << 3) /* backup for host TIF_SVE */
> #define KVM_ARM64_HOST_SVE_ENABLED (1 << 4) /* SVE enabled for EL0 */
> +#define KVM_ARM64_GUEST_HAS_SVE (1 << 5) /* SVE exposed to guest */
> +
> +#define vcpu_has_sve(vcpu) (system_supports_sve() && \
> + ((vcpu)->arch.flags & KVM_ARM64_GUEST_HAS_SVE))

We shouldn't need the system_supports_sve() here. vcpu->arch.flags can
only have the KVM_ARM64_GUEST_HAS_SVE flag set when system_supports_sve()
is true, and it can't change later.

Thanks,
drew

>
> #define vcpu_gp_regs(v) (&(v)->arch.ctxt.gp_regs)
>
> --
> 2.1.4
>
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