Re: [PATCH v2 5/9] arm64: KVM: PMU: Inject UNDEF on read access to PMSWINC_EL0

Christoffer Dall
2017-03-28T12:43:24Z

On Mon, Mar 27, 2017 at 05:03:41PM +0100, Marc Zyngier wrote:
> PMSWINC_EL0 is a WO register, so let's UNDEF when reading from it
> (in the highly hypothetical case where this doesn't UNDEF at EL1).
>
> Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>

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

> ---
> arch/arm64/kvm/sys_regs.c | 13 ++++++-------
> 1 file changed, 6 insertions(+), 7 deletions(-)
>
> diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c
> index 19a036b4f6ac..f80a61af5e88 100644
> --- a/arch/arm64/kvm/sys_regs.c
> +++ b/arch/arm64/kvm/sys_regs.c
> @@ -772,16 +772,15 @@ static bool access_pmswinc(struct kvm_vcpu *vcpu, struct sys_reg_params *p,
> if (!kvm_arm_pmu_v3_ready(vcpu))
> return trap_raz_wi(vcpu, p, r);
>
> + if (!p->is_write)
> + return read_from_write_only(vcpu, p);
> +
> if (pmu_write_swinc_el0_disabled(vcpu))
> return false;
>
> - if (p->is_write) {
> - mask = kvm_pmu_valid_counter_mask(vcpu);
> - kvm_pmu_software_increment(vcpu, p->regval & mask);
> - return true;
> - }
> -
> - return false;
> + mask = kvm_pmu_valid_counter_mask(vcpu);
> + kvm_pmu_software_increment(vcpu, p->regval & mask);
> + return true;
> }
>
> static bool access_pmuserenr(struct kvm_vcpu *vcpu, struct sys_reg_params *p,
> --
> 2.11.0
>