Subject: [PATCH v2 23/28] arm64/sve: KVM: Treat guest SVE use as undefined instruction execution

From: [email-masked] (Alex Bennée)
Date: Thu, 14 Sep 2017 14:31:13 +0100

Dave Martin <[email-masked]> writes:

> When trapping forbidden attempts by a guest to use SVE, we want the
> guest to see a trap consistent with SVE not being implemented.
>
> This patch injects an undefined instruction exception into the
> guest in response to such an exception.

I do wonder if this should be merged with the previous trap enabling
patch though?

>
> Signed-off-by: Dave Martin <[email-masked]>
> ---
>  arch/arm64/kvm/handle_exit.c | 8 ++++++++
>  1 file changed, 8 insertions(+)
>
> diff --git a/arch/arm64/kvm/handle_exit.c b/arch/arm64/kvm/handle_exit.c
> index 17d8a16..e3e42d0 100644
> --- a/arch/arm64/kvm/handle_exit.c
> +++ b/arch/arm64/kvm/handle_exit.c
> @@ -147,6 +147,13 @@ static int kvm_handle_unknown_ec(struct kvm_vcpu *vcpu, struct kvm_run *run)
>  	return 1;
>  }
>
> +static int handle_sve(struct kvm_vcpu *vcpu, struct kvm_run *run)
> +{
> +	/* Until SVE is supported for guests: */
> +	kvm_inject_undefined(vcpu);
> +	return 1;
> +}
> +
>  static exit_handle_fn arm_exit_handlers[] = {
>  	[0 ... ESR_ELx_EC_MAX]	= kvm_handle_unknown_ec,
>  	[ESR_ELx_EC_WFx]	= kvm_handle_wfx,
> @@ -160,6 +167,7 @@ static exit_handle_fn arm_exit_handlers[] = {
>  	[ESR_ELx_EC_HVC64]	= handle_hvc,
>  	[ESR_ELx_EC_SMC64]	= handle_smc,
>  	[ESR_ELx_EC_SYS64]	= kvm_handle_sys_reg,
> +	[ESR_ELx_EC_SVE]	= handle_sve,
>  	[ESR_ELx_EC_IABT_LOW]	= kvm_handle_guest_abort,
>  	[ESR_ELx_EC_DABT_LOW]	= kvm_handle_guest_abort,
>  	[ESR_ELx_EC_SOFTSTP_LOW]= kvm_handle_guest_debug,

--
Alex Benn?e