Re: [PATCH v2 2/9] arm64: KVM: PMU: Inject UNDEF exception on illegal register access

Christoffer Dall
2017-03-28T12:43:00Z

On Mon, Mar 27, 2017 at 05:03:38PM +0100, Marc Zyngier wrote:
> Both pmu_*_el0_disabled() and pmu_counter_idx_valid() perform checks
> on the validity of an access, but only return a boolean indicating
> if the access is valid or not.
>
> Let's allow these functions to also inject an UNDEF exception if
> the access was illegal.
>
> Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>

Reviewed-by: Christoffer Dall <cdall@linaro.org>

> ---
> arch/arm64/kvm/sys_regs.c | 7 ++++++-
> 1 file changed, 6 insertions(+), 1 deletion(-)
>
> diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c
> index 7e1d673304d5..d98ce9a52291 100644
> --- a/arch/arm64/kvm/sys_regs.c
> +++ b/arch/arm64/kvm/sys_regs.c
> @@ -465,6 +465,9 @@ static bool check_disabled(struct kvm_vcpu *vcpu, u64 flags)
> u64 reg = vcpu_sys_reg(vcpu, PMUSERENR_EL0);
> bool cond = (reg & flags) || vcpu_mode_priv(vcpu);
>
> + if (!cond)
> + kvm_inject_undefined(vcpu);
> +
> return !cond;
> }
>
> @@ -564,8 +567,10 @@ static bool pmu_counter_idx_valid(struct kvm_vcpu *vcpu, u64 idx)
>
> pmcr = vcpu_sys_reg(vcpu, PMCR_EL0);
> val = (pmcr >> ARMV8_PMU_PMCR_N_SHIFT) & ARMV8_PMU_PMCR_N_MASK;
> - if (idx >= val && idx != ARMV8_PMU_CYCLE_IDX)
> + if (idx >= val && idx != ARMV8_PMU_CYCLE_IDX) {
> + kvm_inject_undefined(vcpu);
> return false;
> + }
>
> return true;
> }
> --
> 2.11.0
>