On 12/12/19 8:23 PM, Marc Zyngier wrote:
On 2019-12-12 02:45, Gavin Shan wrote:
This standardizes kvm exit reason field name by replacing "esr_ec"
with "exit_reason".
Signed-off-by: Gavin Shan <gshan@xxxxxxxxxx>
---
virt/kvm/arm/trace.h | 14 ++++++++------
1 file changed, 8 insertions(+), 6 deletions(-)
diff --git a/virt/kvm/arm/trace.h b/virt/kvm/arm/trace.h
index 204d210d01c2..0ac774fd324d 100644
--- a/virt/kvm/arm/trace.h
+++ b/virt/kvm/arm/trace.h
@@ -27,25 +27,27 @@ TRACE_EVENT(kvm_entry,
);
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(int ret, unsigned int exit_reason, unsigned long vcpu_pc),
+ TP_ARGS(ret, exit_reason, vcpu_pc),
TP_STRUCT__entry(
__field( int, ret )
- __field( unsigned int, esr_ec )
+ __field( unsigned int, exit_reason )
I don't think the two are the same thing. The exit reason should be
exactly that: why has the guest exited (exception, host interrupt, trap).
What we're reporting here is the exception class, which doesn't apply to
interrupts, for example (hence the 0 down below, which we treat as a
catch-all).
Marc, thanks a lot for your reply. Yeah, the combination (ret and esr_ec) is
complete to indicate the exit reasons if I'm understanding correctly.
The exit reasons seen by kvm_stat is exactly the ESR_EL1[EC]. It's declared
by marcro AARCH64_EXIT_REASONS in tools/kvm/kvm_stat/kvm_stat. So it's precise
and complete from perspective of kvm_stat.
For the patch itself, it standardizes the filter name by renaming "esr_ec"
to "exit_reason", no functional changes introduced and I think it would be
fine.
__field( unsigned long, vcpu_pc )
),
TP_fast_assign(
__entry->ret = ARM_EXCEPTION_CODE(ret);
- __entry->esr_ec = ARM_EXCEPTION_IS_TRAP(ret) ? esr_ec : 0;
+ __entry->exit_reason =
+ ARM_EXCEPTION_IS_TRAP(ret) ? exit_reason: 0;
__entry->vcpu_pc = vcpu_pc;
),
TP_printk("%s: HSR_EC: 0x%04x (%s), PC: 0x%08lx",
__print_symbolic(__entry->ret, kvm_arm_exception_type),
- __entry->esr_ec,
- __print_symbolic(__entry->esr_ec, kvm_arm_exception_class),
+ __entry->exit_reason,
+ __print_symbolic(__entry->exit_reason,
+ kvm_arm_exception_class),
__entry->vcpu_pc)
);
The last thing is whether such a change is an ABI change or not. I've been very
reluctant to change any of this for that reason.
Yeah, I think it is ABI change unfortunately, but I'm not sure how many applications
are using this filter. However, the fixed filter name ("exit_reason") is beneficial
in long run. The application needn't distinguish architects to provide different
tracepoint filters at least.
Regards,
Gavin
