Re: [PATCH v3 23/28] arm64/sve: KVM: Treat guest SVE use as undefined instruction execution

[Christoffer Dall <cdall@linaro.org>]

On Tue, Oct 10, 2017 at 07:38:40PM +0100, Dave Martin wrote:
> 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.
> 
> Signed-off-by: Dave Martin <Dave.Martin@arm.com>
> Reviewed-by: Alex Bennée <alex.bennee@linaro.org>

Acked-by: Christoffer Dall <christoffer.dall@linaro.org>

> ---
>  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 7debb74..b712479 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,
> -- 
> 2.1.4
> 
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