Re: [PATCH v10 05/21] KVM: ARM64: Add access handler for PMSELR register

[Andrew Jones <drjones@redhat.com>]

On Wed, Jan 27, 2016 at 11:51:33AM +0800, Shannon Zhao wrote:
> From: Shannon Zhao <shannon.zhao@linaro.org>
> 
> Since the reset value of PMSELR_EL0 is UNKNOWN, use reset_unknown for
> its reset handler. When reading PMSELR, return the PMSELR.SEL field to
> guest.
> 
> Signed-off-by: Shannon Zhao <shannon.zhao@linaro.org>
> ---
>  arch/arm64/kvm/sys_regs.c | 19 +++++++++++++++++--
>  1 file changed, 17 insertions(+), 2 deletions(-)
> 
> diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c
> index 97fea84..fc60041 100644
> --- a/arch/arm64/kvm/sys_regs.c
> +++ b/arch/arm64/kvm/sys_regs.c
> @@ -477,6 +477,21 @@ static bool access_pmcr(struct kvm_vcpu *vcpu, struct sys_reg_params *p,
>  	return true;
>  }
>  
> +static bool access_pmselr(struct kvm_vcpu *vcpu, struct sys_reg_params *p,
> +			  const struct sys_reg_desc *r)
> +{
> +	if (!kvm_arm_pmu_v3_ready(vcpu))
> +		return trap_raz_wi(vcpu, p, r);
> +
> +	if (p->is_write)
> +		vcpu_sys_reg(vcpu, PMSELR_EL0) = p->regval;

why don't we mask p->regval here when we write vcpu_sys_reg, and then
not need to mask it every time we use it, like below and in later
patches?

> +	else
> +		/* return PMSELR.SEL field */
> +		p->regval = vcpu_sys_reg(vcpu, PMSELR_EL0) & ARMV8_COUNTER_MASK;
> +
> +	return true;
> +}
> +
>  /* Silly macro to expand the DBG{BCR,BVR,WVR,WCR}n_EL1 registers in one go */
>  #define DBG_BCR_BVR_WCR_WVR_EL1(n)					\
>  	/* DBGBVRn_EL1 */						\
> @@ -676,7 +691,7 @@ static const struct sys_reg_desc sys_reg_descs[] = {
>  	  trap_raz_wi },
>  	/* PMSELR_EL0 */
>  	{ Op0(0b11), Op1(0b011), CRn(0b1001), CRm(0b1100), Op2(0b101),
> -	  trap_raz_wi },
> +	  access_pmselr, reset_unknown, PMSELR_EL0 },
>  	/* PMCEID0_EL0 */
>  	{ Op0(0b11), Op1(0b011), CRn(0b1001), CRm(0b1100), Op2(0b110),
>  	  trap_raz_wi },
> @@ -927,7 +942,7 @@ static const struct sys_reg_desc cp15_regs[] = {
>  	{ Op1( 0), CRn( 9), CRm(12), Op2( 1), trap_raz_wi },
>  	{ Op1( 0), CRn( 9), CRm(12), Op2( 2), trap_raz_wi },
>  	{ Op1( 0), CRn( 9), CRm(12), Op2( 3), trap_raz_wi },
> -	{ Op1( 0), CRn( 9), CRm(12), Op2( 5), trap_raz_wi },
> +	{ Op1( 0), CRn( 9), CRm(12), Op2( 5), access_pmselr },
>  	{ Op1( 0), CRn( 9), CRm(12), Op2( 6), trap_raz_wi },
>  	{ Op1( 0), CRn( 9), CRm(12), Op2( 7), trap_raz_wi },
>  	{ Op1( 0), CRn( 9), CRm(13), Op2( 0), trap_raz_wi },
> -- 
> 2.0.4
> 
> 
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