Subject: [PATCH v8 08/20] KVM: ARM64: Add access handler for event typer register

From: [email-masked] (Marc Zyngier)
Date: Thu, 07 Jan 2016 11:03:35 +0000

On 22/12/15 08:08, Shannon Zhao wrote:
> From: Shannon Zhao <[email-masked]>
> 
> These kind of registers include PMEVTYPERn, PMCCFILTR and PMXEVTYPER
> which is mapped to PMEVTYPERn or PMCCFILTR.
> 
> The access handler translates all aarch32 register offsets to aarch64
> ones and uses vcpu_sys_reg() to access their values to avoid taking care
> of big endian.
> 
> When writing to these registers, create a perf_event for the selected
> event type.
> 
> Signed-off-by: Shannon Zhao <[email-masked]>
> ---
>  arch/arm64/kvm/sys_regs.c | 156 +++++++++++++++++++++++++++++++++++++++++++++-
>  1 file changed, 154 insertions(+), 2 deletions(-)
> 
> diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c
> index 2552db1..ed2939b 100644
> --- a/arch/arm64/kvm/sys_regs.c
> +++ b/arch/arm64/kvm/sys_regs.c
> @@ -505,6 +505,70 @@ static bool access_pmceid(struct kvm_vcpu *vcpu, struct sys_reg_params *p,
>  	return true;
>  }
>  
> +static inline bool pmu_counter_idx_valid(struct kvm_vcpu *vcpu, u64 idx)
> +{
> +	u64 pmcr, val;
> +
> +	pmcr = vcpu_sys_reg(vcpu, PMCR_EL0);
> +	val = (pmcr >> ARMV8_PMCR_N_SHIFT) & ARMV8_PMCR_N_MASK;
> +	if (idx >= val && idx != ARMV8_CYCLE_IDX)
> +		return false;
> +
> +	return true;
> +}
> +
> +static bool access_pmu_evtyper(struct kvm_vcpu *vcpu, struct sys_reg_params *p,
> +			       const struct sys_reg_desc *r)
> +{
> +	u64 idx, reg;
> +
> +	if (r->CRn == 9) {
> +		/* PMXEVTYPER_EL0 */
> +		reg = 0;

Is there any particular reason why you're not setting reg to PMSELR_EL0,
since this is what you're using?

> +	} else {
> +		if (!p->is_aarch32) {
> +			/* PMEVTYPERn_EL0 or PMCCFILTR_EL0 */
> +			reg = r->reg;
> +		} else {
> +			if (r->CRn == 14 && r->CRm == 15 && r->Op2 == 7) {
> +				reg = PMCCFILTR_EL0;
> +			} else {
> +				reg = ((r->CRm & 3) << 3) | (r->Op2 & 7);
> +				reg += PMEVTYPER0_EL0;
> +			}
> +		}
> +	}
> +
> +	switch (reg) {
> +	case PMEVTYPER0_EL0 ... PMEVTYPER30_EL0:
> +		idx = reg - PMEVTYPER0_EL0;
> +		if (!pmu_counter_idx_valid(vcpu, idx))
> +			return true;
> +		break;
> +	case PMCCFILTR_EL0:
> +		idx = ARMV8_CYCLE_IDX;
> +		break;
> +	default:

This would allow this case to be more precise, and we could have the
default case as a bug handler.

> +		/* PMXEVTYPER_EL0 */
> +		idx = vcpu_sys_reg(vcpu, PMSELR_EL0) & ARMV8_COUNTER_MASK;
> +		if (!pmu_counter_idx_valid(vcpu, idx))
> +			return true;
> +
> +		reg = (idx == ARMV8_CYCLE_IDX) ? PMCCFILTR_EL0
> +						 : PMEVTYPER0_EL0 + idx;
> +		break;
> +	}
> +
> +	if (p->is_write) {
> +		kvm_pmu_set_counter_event_type(vcpu, p->regval, idx);
> +		vcpu_sys_reg(vcpu, reg) = p->regval & ARMV8_EVTYPE_MASK;
> +	} else {
> +		p->regval = vcpu_sys_reg(vcpu, reg) & ARMV8_EVTYPE_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 */						\
> @@ -520,6 +584,13 @@ static bool access_pmceid(struct kvm_vcpu *vcpu, struct sys_reg_params *p,
>  	{ Op0(0b10), Op1(0b000), CRn(0b0000), CRm((n)), Op2(0b111),	\
>  	  trap_wcr, reset_wcr, n, 0,  get_wcr, set_wcr }
>  
> +/* Macro to expand the PMEVTYPERn_EL0 register */
> +#define PMU_PMEVTYPER_EL0(n)						\
> +	/* PMEVTYPERn_EL0 */						\
> +	{ Op0(0b11), Op1(0b011), CRn(0b1110),				\
> +	  CRm((0b1100 | (((n) >> 3) & 0x3))), Op2(((n) & 0x7)),		\
> +	  access_pmu_evtyper, reset_unknown, (PMEVTYPER0_EL0 + n), }
> +
>  /*
>   * Architected system registers.
>   * Important: Must be sorted ascending by Op0, Op1, CRn, CRm, Op2
> @@ -716,7 +787,7 @@ static const struct sys_reg_desc sys_reg_descs[] = {
>  	  trap_raz_wi },
>  	/* PMXEVTYPER_EL0 */
>  	{ Op0(0b11), Op1(0b011), CRn(0b1001), CRm(0b1101), Op2(0b001),
> -	  trap_raz_wi },
> +	  access_pmu_evtyper },
>  	/* PMXEVCNTR_EL0 */
>  	{ Op0(0b11), Op1(0b011), CRn(0b1001), CRm(0b1101), Op2(0b010),
>  	  trap_raz_wi },
> @@ -734,6 +805,45 @@ static const struct sys_reg_desc sys_reg_descs[] = {
>  	{ Op0(0b11), Op1(0b011), CRn(0b1101), CRm(0b0000), Op2(0b011),
>  	  NULL, reset_unknown, TPIDRRO_EL0 },
>  
> +	/* PMEVTYPERn_EL0 */
> +	PMU_PMEVTYPER_EL0(0),
> +	PMU_PMEVTYPER_EL0(1),
> +	PMU_PMEVTYPER_EL0(2),
> +	PMU_PMEVTYPER_EL0(3),
> +	PMU_PMEVTYPER_EL0(4),
> +	PMU_PMEVTYPER_EL0(5),
> +	PMU_PMEVTYPER_EL0(6),
> +	PMU_PMEVTYPER_EL0(7),
> +	PMU_PMEVTYPER_EL0(8),
> +	PMU_PMEVTYPER_EL0(9),
> +	PMU_PMEVTYPER_EL0(10),
> +	PMU_PMEVTYPER_EL0(11),
> +	PMU_PMEVTYPER_EL0(12),
> +	PMU_PMEVTYPER_EL0(13),
> +	PMU_PMEVTYPER_EL0(14),
> +	PMU_PMEVTYPER_EL0(15),
> +	PMU_PMEVTYPER_EL0(16),
> +	PMU_PMEVTYPER_EL0(17),
> +	PMU_PMEVTYPER_EL0(18),
> +	PMU_PMEVTYPER_EL0(19),
> +	PMU_PMEVTYPER_EL0(20),
> +	PMU_PMEVTYPER_EL0(21),
> +	PMU_PMEVTYPER_EL0(22),
> +	PMU_PMEVTYPER_EL0(23),
> +	PMU_PMEVTYPER_EL0(24),
> +	PMU_PMEVTYPER_EL0(25),
> +	PMU_PMEVTYPER_EL0(26),
> +	PMU_PMEVTYPER_EL0(27),
> +	PMU_PMEVTYPER_EL0(28),
> +	PMU_PMEVTYPER_EL0(29),
> +	PMU_PMEVTYPER_EL0(30),
> +	/* PMCCFILTR_EL0
> +	 * This register resets as unknown in 64bit mode while it resets as zero
> +	 * in 32bit mode. Here we choose to reset it as zero for consistency.
> +	 */
> +	{ Op0(0b11), Op1(0b011), CRn(0b1110), CRm(0b1111), Op2(0b111),
> +	  access_pmu_evtyper, reset_val, PMCCFILTR_EL0, 0 },
> +
>  	/* DACR32_EL2 */
>  	{ Op0(0b11), Op1(0b100), CRn(0b0011), CRm(0b0000), Op2(0b000),
>  	  NULL, reset_unknown, DACR32_EL2 },
> @@ -923,6 +1033,13 @@ static const struct sys_reg_desc cp14_64_regs[] = {
>  	{ Op1( 0), CRm( 2), .access = trap_raz_wi },
>  };
>  
> +/* Macro to expand the PMEVTYPERn register */
> +#define PMU_PMEVTYPER(n)						\
> +	/* PMEVTYPERn */						\
> +	{ Op1(0), CRn(0b1110),						\
> +	  CRm((0b1100 | (((n) >> 3) & 0x3))), Op2(((n) & 0x7)),		\
> +	  access_pmu_evtyper }
> +
>  /*
>   * Trapped cp15 registers. TTBR0/TTBR1 get a double encoding,
>   * depending on the way they are accessed (as a 32bit or a 64bit
> @@ -959,7 +1076,7 @@ static const struct sys_reg_desc cp15_regs[] = {
>  	{ Op1( 0), CRn( 9), CRm(12), Op2( 6), access_pmceid },
>  	{ Op1( 0), CRn( 9), CRm(12), Op2( 7), access_pmceid },
>  	{ Op1( 0), CRn( 9), CRm(13), Op2( 0), trap_raz_wi },
> -	{ Op1( 0), CRn( 9), CRm(13), Op2( 1), trap_raz_wi },
> +	{ Op1( 0), CRn( 9), CRm(13), Op2( 1), access_pmu_evtyper },
>  	{ Op1( 0), CRn( 9), CRm(13), Op2( 2), trap_raz_wi },
>  	{ Op1( 0), CRn( 9), CRm(14), Op2( 0), trap_raz_wi },
>  	{ Op1( 0), CRn( 9), CRm(14), Op2( 1), trap_raz_wi },
> @@ -974,6 +1091,41 @@ static const struct sys_reg_desc cp15_regs[] = {
>  	{ Op1( 0), CRn(12), CRm(12), Op2( 5), trap_raz_wi },
>  
>  	{ Op1( 0), CRn(13), CRm( 0), Op2( 1), access_vm_reg, NULL, c13_CID },
> +
> +	/* PMEVTYPERn */
> +	PMU_PMEVTYPER(0),
> +	PMU_PMEVTYPER(1),
> +	PMU_PMEVTYPER(2),
> +	PMU_PMEVTYPER(3),
> +	PMU_PMEVTYPER(4),
> +	PMU_PMEVTYPER(5),
> +	PMU_PMEVTYPER(6),
> +	PMU_PMEVTYPER(7),
> +	PMU_PMEVTYPER(8),
> +	PMU_PMEVTYPER(9),
> +	PMU_PMEVTYPER(10),
> +	PMU_PMEVTYPER(11),
> +	PMU_PMEVTYPER(12),
> +	PMU_PMEVTYPER(13),
> +	PMU_PMEVTYPER(14),
> +	PMU_PMEVTYPER(15),
> +	PMU_PMEVTYPER(16),
> +	PMU_PMEVTYPER(17),
> +	PMU_PMEVTYPER(18),
> +	PMU_PMEVTYPER(19),
> +	PMU_PMEVTYPER(20),
> +	PMU_PMEVTYPER(21),
> +	PMU_PMEVTYPER(22),
> +	PMU_PMEVTYPER(23),
> +	PMU_PMEVTYPER(24),
> +	PMU_PMEVTYPER(25),
> +	PMU_PMEVTYPER(26),
> +	PMU_PMEVTYPER(27),
> +	PMU_PMEVTYPER(28),
> +	PMU_PMEVTYPER(29),
> +	PMU_PMEVTYPER(30),
> +	/* PMCCFILTR */
> +	{ Op1(0), CRn(14), CRm(15), Op2(7), access_pmu_evtyper },
>  };
>  
>  static const struct sys_reg_desc cp15_64_regs[] = {
> 

Thanks,

	M.
-- 
Jazz is not dead. It just smells funny...