2022-05-03 00:57:37

by Maciej S. Szmigiero

[permalink] [raw]
Subject: [PATCH v3 07/12] KVM: x86: Trace re-injected exceptions

From: Sean Christopherson <[email protected]>

Trace exceptions that are re-injected, not just those that KVM is
injecting for the first time. Debugging re-injection bugs is painful
enough as is, not having visibility into what KVM is doing only makes
things worse.

Delay propagating pending=>injected in the non-reinjection path so that
the tracing can properly identify reinjected exceptions.

Signed-off-by: Sean Christopherson <[email protected]>
Reviewed-by: Maxim Levitsky <[email protected]>
Signed-off-by: Maciej S. Szmigiero <[email protected]>
---
arch/x86/kvm/trace.h | 12 ++++++++----
arch/x86/kvm/x86.c | 16 +++++++++-------
2 files changed, 17 insertions(+), 11 deletions(-)

diff --git a/arch/x86/kvm/trace.h b/arch/x86/kvm/trace.h
index de4762517569..d07428e660e3 100644
--- a/arch/x86/kvm/trace.h
+++ b/arch/x86/kvm/trace.h
@@ -358,25 +358,29 @@ TRACE_EVENT(kvm_inj_virq,
* Tracepoint for kvm interrupt injection:
*/
TRACE_EVENT(kvm_inj_exception,
- TP_PROTO(unsigned exception, bool has_error, unsigned error_code),
- TP_ARGS(exception, has_error, error_code),
+ TP_PROTO(unsigned exception, bool has_error, unsigned error_code,
+ bool reinjected),
+ TP_ARGS(exception, has_error, error_code, reinjected),

TP_STRUCT__entry(
__field( u8, exception )
__field( u8, has_error )
__field( u32, error_code )
+ __field( bool, reinjected )
),

TP_fast_assign(
__entry->exception = exception;
__entry->has_error = has_error;
__entry->error_code = error_code;
+ __entry->reinjected = reinjected;
),

- TP_printk("%s (0x%x)",
+ TP_printk("%s (0x%x)%s",
__print_symbolic(__entry->exception, kvm_trace_sym_exc),
/* FIXME: don't print error_code if not present */
- __entry->has_error ? __entry->error_code : 0)
+ __entry->has_error ? __entry->error_code : 0,
+ __entry->reinjected ? " [reinjected]" : "")
);

/*
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 1abce22b14d7..a41d616ad943 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -9393,6 +9393,11 @@ int kvm_check_nested_events(struct kvm_vcpu *vcpu)

static void kvm_inject_exception(struct kvm_vcpu *vcpu)
{
+ trace_kvm_inj_exception(vcpu->arch.exception.nr,
+ vcpu->arch.exception.has_error_code,
+ vcpu->arch.exception.error_code,
+ vcpu->arch.exception.injected);
+
if (vcpu->arch.exception.error_code && !is_protmode(vcpu))
vcpu->arch.exception.error_code = false;
static_call(kvm_x86_queue_exception)(vcpu);
@@ -9450,13 +9455,6 @@ static int inject_pending_event(struct kvm_vcpu *vcpu, bool *req_immediate_exit)

/* try to inject new event if pending */
if (vcpu->arch.exception.pending) {
- trace_kvm_inj_exception(vcpu->arch.exception.nr,
- vcpu->arch.exception.has_error_code,
- vcpu->arch.exception.error_code);
-
- vcpu->arch.exception.pending = false;
- vcpu->arch.exception.injected = true;
-
if (exception_type(vcpu->arch.exception.nr) == EXCPT_FAULT)
__kvm_set_rflags(vcpu, kvm_get_rflags(vcpu) |
X86_EFLAGS_RF);
@@ -9470,6 +9468,10 @@ static int inject_pending_event(struct kvm_vcpu *vcpu, bool *req_immediate_exit)
}

kvm_inject_exception(vcpu);
+
+ vcpu->arch.exception.pending = false;
+ vcpu->arch.exception.injected = true;
+
can_inject = false;
}