On 2015/10/16 23:06, Wei Huang wrote:

On 09/24/2015 05:31 PM, Shannon Zhao wrote:

quoted

Since the reset value of PMCCNTR is UNKNOWN, use reset_unknown for its
reset handler. Add a new case to emulate reading to PMCCNTR register.

Signed-off-by: Shannon Zhao <redacted>
---
 arch/arm64/kvm/sys_regs.c | 17 +++++++++++++++--
 1 file changed, 15 insertions(+), 2 deletions(-)

diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c
index e7f6058..c38c2de 100644
--- a/arch/arm64/kvm/sys_regs.c
+++ b/arch/arm64/kvm/sys_regs.c

@@ -518,6 +518,12 @@ static bool access_pmu_regs(struct kvm_vcpu *vcpu,
 		}
 	} else {
 		switch (r->reg) {
+		case PMCCNTR_EL0: {
+			val = kvm_pmu_get_counter_value(vcpu,
+							ARMV8_MAX_COUNTERS - 1);
+			*vcpu_reg(vcpu, p->Rt) = val;
+			break;
+		}
 		case PMXEVCNTR_EL0: {
 			val = kvm_pmu_get_counter_value(vcpu,
 						vcpu_sys_reg(vcpu, PMSELR_EL0));

@@ -748,7 +754,7 @@ static const struct sys_reg_desc sys_reg_descs[] = {
 	  access_pmu_regs, reset_pmceid, PMCEID1_EL0 },
 	/* PMCCNTR_EL0 */
 	{ Op0(0b11), Op1(0b011), CRn(0b1001), CRm(0b1101), Op2(0b000),
-	  trap_raz_wi },
+	  access_pmu_regs, reset_unknown, PMCCNTR_EL0 },
 	/* PMXEVTYPER_EL0 */
 	{ Op0(0b11), Op1(0b011), CRn(0b1001), CRm(0b1101), Op2(0b001),
 	  access_pmu_regs, reset_unknown, PMXEVTYPER_EL0 },

@@ -997,6 +1003,12 @@ static bool access_pmu_cp15_regs(struct kvm_vcpu *vcpu,
 		}
 	} else {
 		switch (r->reg) {
+		case c9_PMCCNTR: {
+			val = kvm_pmu_get_counter_value(vcpu,
+							ARMV8_MAX_COUNTERS - 1);

PMCCNTR is for cycle counter. There is a filter register, PMCCFILTR_EL0,
associated with it. When kvm_pmu_set_counter_event_type() is called, I
didn't see this filter config been used in perf_event_attr when
perf_event is created.

According to the spec, to PMXEVTYPER_EL0 it says "When PMSELR_EL0.SEL
selects the cycle counter, this accesses PMCCFILTR_EL0." So within
kvm_pmu_set_counter_event_type, I configure the perf_event_attr based on
the bits of PMXEVTYPER_EL0 and only handle bit P for EL0 and bit U for
EL1 since KVM guest doesn't see EL2 and EL3.

See patch 07/20 :
+	attr.exclude_user = data & ARMV8_EXCLUDE_EL0 ? 1 : 0;
+	attr.exclude_kernel = data & ARMV8_EXCLUDE_EL1 ? 1 : 0;


-- 
Shannon