Re: [PATCH 06/18] KVM: ARM64: Add reset and access handlers for PMCEID0_EL0 and PMCEID1_EL0 register

[Christoffer Dall <christoffer.dall@linaro.org>]

On Mon, Jul 06, 2015 at 10:17:36AM +0800, shannon.zhao@linaro.org wrote:
> From: Shannon Zhao <shannon.zhao@linaro.org>
> 
> Add reset handler which gets host value of PMCEID0_EL0 or PMCEID1_EL0.
> Add access handler which emulates writing and reading PMCEID0_EL0 or
> PMCEID1_EL0 register.
> 
> Signed-off-by: Shannon Zhao <shannon.zhao@linaro.org>
> ---
>  arch/arm64/kvm/sys_regs.c | 36 ++++++++++++++++++++++++++++++++++--
>  1 file changed, 34 insertions(+), 2 deletions(-)
> 
> diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c
> index 69c8c48..1df9ef3 100644
> --- a/arch/arm64/kvm/sys_regs.c
> +++ b/arch/arm64/kvm/sys_regs.c
> @@ -246,6 +246,19 @@ static void reset_pmcr_el0(struct kvm_vcpu *vcpu, const struct sys_reg_desc *r)
>  				       | (ARMV8_PMCR_MASK & 0xdecafbad);
>  }
>  
> +static void reset_pmceid(struct kvm_vcpu *vcpu, const struct sys_reg_desc *r)
> +{
> +	u32 pmceid;
> +
> +	if (r->reg == PMCEID0_EL0) {
> +		asm volatile("mrs %0, pmceid0_el0\n" : "=r" (pmceid));
> +		vcpu_sys_reg(vcpu, r->reg) = pmceid;
> +	} else {

add /* PMCEID1_EL1 */
> +		asm volatile("mrs %0, pmceid1_el0\n" : "=r" (pmceid));
> +		vcpu_sys_reg(vcpu, r->reg) = pmceid;
> +	}
> +}
> +
>  /* PMCR_EL0 accessor. Only called as long as MDCR_EL2.TPMCR is set. */
>  static bool access_pmcr(struct kvm_vcpu *vcpu,
>  			const struct sys_reg_params *p,
> @@ -299,6 +312,25 @@ static bool access_pmselr(struct kvm_vcpu *vcpu,
>  	return true;
>  }
>  
> +/* PMCEID0_EL0 and PMCEID1_EL0 accessor. */
> +static bool access_pmceid(struct kvm_vcpu *vcpu,
> +			  const struct sys_reg_params *p,
> +			  const struct sys_reg_desc *r)
> +{
> +	unsigned long val;
> +
> +	if (p->is_write) {
> +		return ignore_write(vcpu, p);
> +	} else {
> +		if (!p->is_aarch32)
> +			val = vcpu_sys_reg(vcpu, r->reg);
> +		else
> +			val = vcpu_cp15(vcpu, r->reg);
> +		*vcpu_reg(vcpu, p->Rt) = val;
> +		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 */						\
> @@ -508,10 +540,10 @@ static const struct sys_reg_desc sys_reg_descs[] = {
>  	  access_pmselr, reset_unknown, PMSELR_EL0 },
>  	/* PMCEID0_EL0 */
>  	{ Op0(0b11), Op1(0b011), CRn(0b1001), CRm(0b1100), Op2(0b110),
> -	  trap_raz_wi },
> +	  access_pmceid, reset_pmceid, PMCEID0_EL0, },
>  	/* PMCEID1_EL0 */
>  	{ Op0(0b11), Op1(0b011), CRn(0b1001), CRm(0b1100), Op2(0b111),
> -	  trap_raz_wi },
> +	  access_pmceid, reset_pmceid, PMCEID1_EL0, },
>  	/* PMCCNTR_EL0 */
>  	{ Op0(0b11), Op1(0b011), CRn(0b1001), CRm(0b1101), Op2(0b000),
>  	  trap_raz_wi },
> -- 
> 2.1.0
> 
same comment wrt. 32-bit table.

-Christoffer