On 2016/1/29 4:11, Andrew Jones wrote:

On Wed, Jan 27, 2016 at 11:51:36AM +0800, Shannon Zhao wrote:

quoted

quoted

From: Shannon Zhao <redacted>

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 <redacted>
---
 arch/arm64/kvm/sys_regs.c | 140 +++++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 138 insertions(+), 2 deletions(-)

diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c
index 06257e2..298ae94 100644
--- a/arch/arm64/kvm/sys_regs.c
+++ b/arch/arm64/kvm/sys_regs.c

@@ -513,6 +513,54 @@ static bool access_pmceid(struct kvm_vcpu *vcpu, struct sys_reg_params *p,
 	return true;
 }
 
+static 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 (!kvm_arm_pmu_v3_ready(vcpu))
+		return trap_raz_wi(vcpu, p, r);
+
+	if (r->CRn == 9 && r->CRm == 13 && r->Op2 == 1) {
+		/* PMXEVTYPER_EL0 */
+		idx = vcpu_sys_reg(vcpu, PMSELR_EL0) & ARMV8_COUNTER_MASK;
+		reg = PMEVTYPER0_EL0 + idx;
+	} else if (r->CRn == 14 && (r->CRm & 12) == 12) {
+		idx = ((r->CRm & 3) << 3) | (r->Op2 & 7);
+		if (idx == ARMV8_CYCLE_IDX)
+			reg = PMCCFILTR_EL0;
+		else
+			/* PMEVTYPERn_EL0 */
+			reg = PMEVTYPER0_EL0 + idx;
+	} else {
+		BUG();
+	}
+
+	if (!pmu_counter_idx_valid(vcpu, idx))
+		return false;
+
+	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;

Related to my comment in 5/21. Why should we need to mask it here when
reading it, since it was masked on writing?

But what if guest reads this register before writing to it?

Thanks,
-- 
Shannon