Merge branch kvm-arm64/pmu/reset-values into kvmarm-master/next

Fix the reset values for our PMU emulation. As a side effect,
it allows a nice optimisation by only tracking the in-use
counters when flipping them on and off, now that we are
guaranteed not to have any spurious bit set.

* kvm-arm64/pmu/reset-values:
  KVM: arm64: Remove PMSWINC_EL0 shadow register
  KVM: arm64: Disabling disabled PMU counters wastes a lot of time
  KVM: arm64: Drop unnecessary masking of PMU registers
  KVM: arm64: Narrow PMU sysreg reset values to architectural requirements

Signed-off-by: Marc Zyngier <maz@kernel.org>

arch/arm64/include/asm/kvm_host.h

@@ -185,7 +185,6 @@ enum vcpu_sysreg {
 	PMCNTENSET_EL0,	/* Count Enable Set Register */
 	PMINTENSET_EL1,	/* Interrupt Enable Set Register */
 	PMOVSSET_EL0,	/* Overflow Flag Status Set Register */
-	PMSWINC_EL0,	/* Software Increment Register */
 	PMUSERENR_EL0,	/* User Enable Register */
 
 	/* Pointer Authentication Registers in a strict increasing order. */

arch/arm64/kvm/pmu-emul.c

@@ -373,7 +373,6 @@ static u64 kvm_pmu_overflow_status(struct kvm_vcpu *vcpu)
 		reg = __vcpu_sys_reg(vcpu, PMOVSSET_EL0);
 		reg &= __vcpu_sys_reg(vcpu, PMCNTENSET_EL0);
 		reg &= __vcpu_sys_reg(vcpu, PMINTENSET_EL1);
-		reg &= kvm_pmu_valid_counter_mask(vcpu);
 	}
 
 	return reg;
@@ -564,20 +563,21 @@ void kvm_pmu_software_increment(struct kvm_vcpu *vcpu, u64 val)
  */
 void kvm_pmu_handle_pmcr(struct kvm_vcpu *vcpu, u64 val)
 {
-	unsigned long mask = kvm_pmu_valid_counter_mask(vcpu);
 	int i;
 
 	if (val & ARMV8_PMU_PMCR_E) {
 		kvm_pmu_enable_counter_mask(vcpu,
-		       __vcpu_sys_reg(vcpu, PMCNTENSET_EL0) & mask);
+		       __vcpu_sys_reg(vcpu, PMCNTENSET_EL0));
 	} else {
-		kvm_pmu_disable_counter_mask(vcpu, mask);
+		kvm_pmu_disable_counter_mask(vcpu,
+		       __vcpu_sys_reg(vcpu, PMCNTENSET_EL0));
 	}
 
 	if (val & ARMV8_PMU_PMCR_C)
 		kvm_pmu_set_counter_value(vcpu, ARMV8_PMU_CYCLE_IDX, 0);
 
 	if (val & ARMV8_PMU_PMCR_P) {
+		unsigned long mask = kvm_pmu_valid_counter_mask(vcpu);
 		mask &= ~BIT(ARMV8_PMU_CYCLE_IDX);
 		for_each_set_bit(i, &mask, 32)
 			kvm_pmu_set_counter_value(vcpu, i, 0);

arch/arm64/kvm/sys_regs.c

@@ -603,6 +603,41 @@ static unsigned int pmu_visibility(const struct kvm_vcpu *vcpu,
 	return REG_HIDDEN;
 }
 
+static void reset_pmu_reg(struct kvm_vcpu *vcpu, const struct sys_reg_desc *r)
+{
+	u64 n, mask = BIT(ARMV8_PMU_CYCLE_IDX);
+
+	/* No PMU available, any PMU reg may UNDEF... */
+	if (!kvm_arm_support_pmu_v3())
+		return;
+
+	n = read_sysreg(pmcr_el0) >> ARMV8_PMU_PMCR_N_SHIFT;
+	n &= ARMV8_PMU_PMCR_N_MASK;
+	if (n)
+		mask |= GENMASK(n - 1, 0);
+
+	reset_unknown(vcpu, r);
+	__vcpu_sys_reg(vcpu, r->reg) &= mask;
+}
+
+static void reset_pmevcntr(struct kvm_vcpu *vcpu, const struct sys_reg_desc *r)
+{
+	reset_unknown(vcpu, r);
+	__vcpu_sys_reg(vcpu, r->reg) &= GENMASK(31, 0);
+}
+
+static void reset_pmevtyper(struct kvm_vcpu *vcpu, const struct sys_reg_desc *r)
+{
+	reset_unknown(vcpu, r);
+	__vcpu_sys_reg(vcpu, r->reg) &= ARMV8_PMU_EVTYPE_MASK;
+}
+
+static void reset_pmselr(struct kvm_vcpu *vcpu, const struct sys_reg_desc *r)
+{
+	reset_unknown(vcpu, r);
+	__vcpu_sys_reg(vcpu, r->reg) &= ARMV8_PMU_COUNTER_MASK;
+}
+
 static void reset_pmcr(struct kvm_vcpu *vcpu, const struct sys_reg_desc *r)
 {
 	u64 pmcr, val;
@@ -845,7 +880,7 @@ static bool access_pmcnten(struct kvm_vcpu *vcpu, struct sys_reg_params *p,
 			kvm_pmu_disable_counter_mask(vcpu, val);
 		}
 	} else {
-		p->regval = __vcpu_sys_reg(vcpu, PMCNTENSET_EL0) & mask;
+		p->regval = __vcpu_sys_reg(vcpu, PMCNTENSET_EL0);
 	}
 
 	return true;
@@ -869,7 +904,7 @@ static bool access_pminten(struct kvm_vcpu *vcpu, struct sys_reg_params *p,
 			/* accessing PMINTENCLR_EL1 */
 			__vcpu_sys_reg(vcpu, PMINTENSET_EL1) &= ~val;
 	} else {
-		p->regval = __vcpu_sys_reg(vcpu, PMINTENSET_EL1) & mask;
+		p->regval = __vcpu_sys_reg(vcpu, PMINTENSET_EL1);
 	}
 
 	return true;
@@ -891,7 +926,7 @@ static bool access_pmovs(struct kvm_vcpu *vcpu, struct sys_reg_params *p,
 			/* accessing PMOVSCLR_EL0 */
 			__vcpu_sys_reg(vcpu, PMOVSSET_EL0) &= ~(p->regval & mask);
 	} else {
-		p->regval = __vcpu_sys_reg(vcpu, PMOVSSET_EL0) & mask;
+		p->regval = __vcpu_sys_reg(vcpu, PMOVSSET_EL0);
 	}
 
 	return true;
@@ -944,16 +979,18 @@ static bool access_pmuserenr(struct kvm_vcpu *vcpu, struct sys_reg_params *p,
 	  trap_wcr, reset_wcr, 0, 0,  get_wcr, set_wcr }
 
 #define PMU_SYS_REG(r)						\
-	SYS_DESC(r), .reset = reset_unknown, .visibility = pmu_visibility
+	SYS_DESC(r), .reset = reset_pmu_reg, .visibility = pmu_visibility
 
 /* Macro to expand the PMEVCNTRn_EL0 register */
 #define PMU_PMEVCNTR_EL0(n)						\
 	{ PMU_SYS_REG(SYS_PMEVCNTRn_EL0(n)),				\
+	  .reset = reset_pmevcntr,					\
 	  .access = access_pmu_evcntr, .reg = (PMEVCNTR0_EL0 + n), }
 
 /* Macro to expand the PMEVTYPERn_EL0 register */
 #define PMU_PMEVTYPER_EL0(n)						\
 	{ PMU_SYS_REG(SYS_PMEVTYPERn_EL0(n)),				\
+	  .reset = reset_pmevtyper,					\
 	  .access = access_pmu_evtyper, .reg = (PMEVTYPER0_EL0 + n), }
 
 static bool undef_access(struct kvm_vcpu *vcpu, struct sys_reg_params *p,
@@ -1249,6 +1286,20 @@ static int set_raz_id_reg(struct kvm_vcpu *vcpu, const struct sys_reg_desc *rd,
 	return __set_id_reg(vcpu, rd, uaddr, true);
 }
 
+static int set_wi_reg(struct kvm_vcpu *vcpu, const struct sys_reg_desc *rd,
+		      const struct kvm_one_reg *reg, void __user *uaddr)
+{
+	int err;
+	u64 val;
+
+	/* Perform the access even if we are going to ignore the value */
+	err = reg_from_user(&val, uaddr, sys_reg_to_index(rd));
+	if (err)
+		return err;
+
+	return 0;
+}
+
 static bool access_ctr(struct kvm_vcpu *vcpu, struct sys_reg_params *p,
 		       const struct sys_reg_desc *r)
 {
@@ -1592,16 +1643,21 @@ static const struct sys_reg_desc sys_reg_descs[] = {
 	  .access = access_pmcnten, .reg = PMCNTENSET_EL0 },
 	{ PMU_SYS_REG(SYS_PMOVSCLR_EL0),
 	  .access = access_pmovs, .reg = PMOVSSET_EL0 },
+	/*
+	 * PM_SWINC_EL0 is exposed to userspace as RAZ/WI, as it was
+	 * previously (and pointlessly) advertised in the past...
+	 */
 	{ PMU_SYS_REG(SYS_PMSWINC_EL0),
-	  .access = access_pmswinc, .reg = PMSWINC_EL0 },
+	  .get_user = get_raz_id_reg, .set_user = set_wi_reg,
+	  .access = access_pmswinc, .reset = NULL },
 	{ PMU_SYS_REG(SYS_PMSELR_EL0),
-	  .access = access_pmselr, .reg = PMSELR_EL0 },
+	  .access = access_pmselr, .reset = reset_pmselr, .reg = PMSELR_EL0 },
 	{ PMU_SYS_REG(SYS_PMCEID0_EL0),
 	  .access = access_pmceid, .reset = NULL },
 	{ PMU_SYS_REG(SYS_PMCEID1_EL0),
 	  .access = access_pmceid, .reset = NULL },
 	{ PMU_SYS_REG(SYS_PMCCNTR_EL0),
-	  .access = access_pmu_evcntr, .reg = PMCCNTR_EL0 },
+	  .access = access_pmu_evcntr, .reset = reset_unknown, .reg = PMCCNTR_EL0 },
 	{ PMU_SYS_REG(SYS_PMXEVTYPER_EL0),
 	  .access = access_pmu_evtyper, .reset = NULL },
 	{ PMU_SYS_REG(SYS_PMXEVCNTR_EL0),