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Subject[PATCH v1 2/5] KVM: arm/arm64: Adjust entry/exit and trap related tracepoints
Date
Currently, we use trace_kvm_exit() to report exception type (e.g.,
"IRQ", "TRAP") and exception class (ESR_ELx's bit[31:26]) together.
But hardware only saves the exit class to ESR_ELx on synchronous
exceptions, not on asynchronous exceptions. When the guest exits
due to external interrupts, we will get tracing output like:

"kvm_exit: IRQ: HSR_EC: 0x0000 (UNKNOWN), PC: 0xffff87259e30"

Obviously, "HSR_EC" here is meaningless.

This patch splits "exit" and "trap" events by adding two tracepoints
explicitly in handle_trap_exceptions(). Let trace_kvm_exit() report VM
exit events, and trace_kvm_trap_exit() report VM trap events.

These tracepoints are adjusted also in preparation for supporting
'perf kvm stat' on arm64.

Cc: Christoffer Dall <christoffer.dall@arm.com>
Cc: Marc Zyngier <marc.zyngier@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Signed-off-by: Zenghui Yu <yuzenghui@huawei.com>
---
arch/arm64/kvm/handle_exit.c | 3 +++
arch/arm64/kvm/trace.h | 35 +++++++++++++++++++++++++++++++++++
virt/kvm/arm/arm.c | 4 ++--
virt/kvm/arm/trace.h | 21 +++++++++++----------
4 files changed, 51 insertions(+), 12 deletions(-)

diff --git a/arch/arm64/kvm/handle_exit.c b/arch/arm64/kvm/handle_exit.c
index 516aead..af3c732 100644
--- a/arch/arm64/kvm/handle_exit.c
+++ b/arch/arm64/kvm/handle_exit.c
@@ -264,7 +264,10 @@ static int handle_trap_exceptions(struct kvm_vcpu *vcpu, struct kvm_run *run)
exit_handle_fn exit_handler;

exit_handler = kvm_get_exit_handler(vcpu);
+ trace_kvm_trap_enter(vcpu->vcpu_id,
+ kvm_vcpu_trap_get_class(vcpu));
handled = exit_handler(vcpu, run);
+ trace_kvm_trap_exit(vcpu->vcpu_id);
}

return handled;
diff --git a/arch/arm64/kvm/trace.h b/arch/arm64/kvm/trace.h
index eab91ad..6014c73 100644
--- a/arch/arm64/kvm/trace.h
+++ b/arch/arm64/kvm/trace.h
@@ -8,6 +8,41 @@
#undef TRACE_SYSTEM
#define TRACE_SYSTEM kvm

+TRACE_EVENT(kvm_trap_enter,
+ TP_PROTO(unsigned int vcpu_id, unsigned int esr_ec),
+ TP_ARGS(vcpu_id, esr_ec),
+
+ TP_STRUCT__entry(
+ __field(unsigned int, vcpu_id)
+ __field(unsigned int, esr_ec)
+ ),
+
+ TP_fast_assign(
+ __entry->vcpu_id = vcpu_id;
+ __entry->esr_ec = esr_ec;
+ ),
+
+ TP_printk("VCPU %u: HSR_EC=0x%04x (%s)",
+ __entry->vcpu_id,
+ __entry->esr_ec,
+ __print_symbolic(__entry->esr_ec, kvm_arm_exception_class))
+);
+
+TRACE_EVENT(kvm_trap_exit,
+ TP_PROTO(unsigned int vcpu_id),
+ TP_ARGS(vcpu_id),
+
+ TP_STRUCT__entry(
+ __field(unsigned int, vcpu_id)
+ ),
+
+ TP_fast_assign(
+ __entry->vcpu_id = vcpu_id;
+ ),
+
+ TP_printk("VCPU %u", __entry->vcpu_id)
+);
+
TRACE_EVENT(kvm_wfx_arm64,
TP_PROTO(unsigned long vcpu_pc, bool is_wfe),
TP_ARGS(vcpu_pc, is_wfe),
diff --git a/virt/kvm/arm/arm.c b/virt/kvm/arm/arm.c
index 90cedeb..9f63fd9 100644
--- a/virt/kvm/arm/arm.c
+++ b/virt/kvm/arm/arm.c
@@ -758,7 +758,7 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu, struct kvm_run *run)
/**************************************************************
* Enter the guest
*/
- trace_kvm_entry(*vcpu_pc(vcpu));
+ trace_kvm_entry(vcpu->vcpu_id, *vcpu_pc(vcpu));
guest_enter_irqoff();

if (has_vhe()) {
@@ -822,7 +822,7 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu, struct kvm_run *run)
* guest time.
*/
guest_exit();
- trace_kvm_exit(ret, kvm_vcpu_trap_get_class(vcpu), *vcpu_pc(vcpu));
+ trace_kvm_exit(vcpu->vcpu_id, ret, *vcpu_pc(vcpu));

/* Exit types that need handling before we can be preempted */
handle_exit_early(vcpu, run, ret);
diff --git a/virt/kvm/arm/trace.h b/virt/kvm/arm/trace.h
index 8b7dff2..edd9dae 100644
--- a/virt/kvm/arm/trace.h
+++ b/virt/kvm/arm/trace.h
@@ -12,40 +12,41 @@
* Tracepoints for entry/exit to guest
*/
TRACE_EVENT(kvm_entry,
- TP_PROTO(unsigned long vcpu_pc),
- TP_ARGS(vcpu_pc),
+ TP_PROTO(unsigned int vcpu_id, unsigned long vcpu_pc),
+ TP_ARGS(vcpu_id, vcpu_pc),

TP_STRUCT__entry(
+ __field( unsigned int, vcpu_id )
__field( unsigned long, vcpu_pc )
),

TP_fast_assign(
+ __entry->vcpu_id = vcpu_id;
__entry->vcpu_pc = vcpu_pc;
),

- TP_printk("PC: 0x%08lx", __entry->vcpu_pc)
+ TP_printk("VCPU %u: PC=0x%08lx", __entry->vcpu_id, __entry->vcpu_pc)
);

TRACE_EVENT(kvm_exit,
- TP_PROTO(int ret, unsigned int esr_ec, unsigned long vcpu_pc),
- TP_ARGS(ret, esr_ec, vcpu_pc),
+ TP_PROTO(unsigned int vcpu_id, int ret, unsigned long vcpu_pc),
+ TP_ARGS(vcpu_id, ret, vcpu_pc),

TP_STRUCT__entry(
+ __field( unsigned int, vcpu_id )
__field( int, ret )
- __field( unsigned int, esr_ec )
__field( unsigned long, vcpu_pc )
),

TP_fast_assign(
+ __entry->vcpu_id = vcpu_id;
__entry->ret = ARM_EXCEPTION_CODE(ret);
- __entry->esr_ec = ARM_EXCEPTION_IS_TRAP(ret) ? esr_ec : 0;
__entry->vcpu_pc = vcpu_pc;
),

- TP_printk("%s: HSR_EC: 0x%04x (%s), PC: 0x%08lx",
+ TP_printk("VCPU %u: exit_type=%s, PC=0x%08lx",
+ __entry->vcpu_id,
__print_symbolic(__entry->ret, kvm_arm_exception_type),
- __entry->esr_ec,
- __print_symbolic(__entry->esr_ec, kvm_arm_exception_class),
__entry->vcpu_pc)
);

--
1.8.3.1

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