Re: [PATCH v6 08/21] KVM: ARM64: Add access handler for PMEVTYPERn and PMCCFILTR register

[Marc Zyngier <marc.zyngier@arm.com>]

On 08/12/15 12:47, Shannon Zhao wrote:
> From: Shannon Zhao <shannon.zhao@linaro.org>
> 
> Add access handler which emulates writing and reading PMEVTYPERn or
> PMCCFILTR register. When writing to PMEVTYPERn or PMCCFILTR, call
> kvm_pmu_set_counter_event_type to create a perf_event for the selected
> event type.
> 
> Signed-off-by: Shannon Zhao <shannon.zhao@linaro.org>
> ---
>  arch/arm64/kvm/sys_regs.c | 98 +++++++++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 98 insertions(+)
> 
> diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c
> index 1bcb2b7..2d8bd15 100644
> --- a/arch/arm64/kvm/sys_regs.c
> +++ b/arch/arm64/kvm/sys_regs.c
> @@ -474,6 +474,12 @@ static bool access_pmu_regs(struct kvm_vcpu *vcpu,
>  
>  	if (p->is_write) {
>  		switch (r->reg) {
> +		case PMEVTYPER0_EL0 ... PMCCFILTR_EL0: {

Please don't do that, this is dangerous.

I'm fine with PMEVTYPER0_EL0 ... PMEVTYPER30_EL0, but not with
PMCCFILTR_EL0. It could have been moved to another offset in the
register file, and nobody would notice this. So keep it as a separate
case statement.

> +			val = r->reg - PMEVTYPER0_EL0;
> +			kvm_pmu_set_counter_event_type(vcpu, p->regval, val);
> +			vcpu_sys_reg(vcpu, r->reg) = p->regval;
> +			break;
> +		}
>  		case PMCR_EL0: {
>  			/* Only update writeable bits of PMCR */
>  			val = vcpu_sys_reg(vcpu, r->reg);
> @@ -522,6 +528,13 @@ static bool access_pmu_regs(struct kvm_vcpu *vcpu,
>  	{ 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_regs, reset_unknown, (PMEVTYPER0_EL0 + n), }
> +
>  /*
>   * Architected system registers.
>   * Important: Must be sorted ascending by Op0, Op1, CRn, CRm, Op2
> @@ -736,6 +749,42 @@ 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 */
> +	{ Op0(0b11), Op1(0b011), CRn(0b1110), CRm(0b1111), Op2(0b111),
> +	  access_pmu_regs, reset_unknown, PMCCFILTR_EL0, },
> +
>  	/* DACR32_EL2 */
>  	{ Op0(0b11), Op1(0b100), CRn(0b0011), CRm(0b0000), Op2(0b000),
>  	  NULL, reset_unknown, DACR32_EL2 },
> @@ -934,6 +983,12 @@ static bool access_pmu_cp15_regs(struct kvm_vcpu *vcpu,
>  
>  	if (p->is_write) {
>  		switch (r->reg) {
> +		case c14_PMEVTYPER0 ... c14_PMCCFILTR: {

Same problem here.

> +			val = r->reg - c14_PMEVTYPER0;
> +			kvm_pmu_set_counter_event_type(vcpu, p->regval, val);
> +			vcpu_cp15(vcpu, r->reg) = p->regval;
> +			break;
> +		}
>  		case c9_PMCR: {
>  			/* Only update writeable bits of PMCR */
>  			val = vcpu_cp15(vcpu, r->reg);
> @@ -967,6 +1022,13 @@ static bool access_pmu_cp15_regs(struct kvm_vcpu *vcpu,
>  	return true;
>  }
>  
> +/* 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_cp15_regs, NULL, (c14_PMEVTYPER0 + n), }
> +
>  /*
>   * Trapped cp15 registers. TTBR0/TTBR1 get a double encoding,
>   * depending on the way they are accessed (as a 32bit or a 64bit
> @@ -1022,6 +1084,42 @@ 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_cp15_regs,
> +	  NULL, c14_PMCCFILTR },
>  };
>  
>  static const struct sys_reg_desc cp15_64_regs[] = {
> 

Thanks,

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