On Sun, Nov 30, 2025 at 07:00:52PM +0000, Marc Zyngier wrote:

On Fri, 07 Nov 2025 09:38:38 +0000,
Vincent Donnefort [off-list ref] wrote:

quoted

The hyp_enter and hyp_exit events are logged by the hypervisor any time
it is entered and exited.

Signed-off-by: Vincent Donnefort <redacted>

diff --git a/arch/arm64/include/asm/kvm_hypevents.h b/arch/arm64/include/asm/kvm_hypevents.h
index d6e033c96c52..ce3953bc884a 100644
--- a/arch/arm64/include/asm/kvm_hypevents.h
+++ b/arch/arm64/include/asm/kvm_hypevents.h

@@ -7,4 +7,21 @@
 #include <nvhe/trace.h>
 #endif
 
+HYP_EVENT(hyp_enter,
+	HE_PROTO(void),
+	HE_STRUCT(
+	),
+	HE_ASSIGN(
+	),
+	HE_PRINTK()
+);
+
+HYP_EVENT(hyp_exit,
+	HE_PROTO(void),
+	HE_STRUCT(
+	),
+	HE_ASSIGN(
+	),
+	HE_PRINTK()
+);
 #endif

diff --git a/arch/arm64/kvm/hyp/include/nvhe/arm-smccc.h b/arch/arm64/kvm/hyp/include/nvhe/arm-smccc.h
new file mode 100644
index 000000000000..4b69d33e4f2d
--- /dev/null
+++ b/arch/arm64/kvm/hyp/include/nvhe/arm-smccc.h

@@ -0,0 +1,13 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+
+#include <asm/kvm_hypevents.h>
+
+#include <linux/arm-smccc.h>
+
+#undef arm_smccc_1_1_smc
+#define arm_smccc_1_1_smc(...)					\
+	do {							\
+		trace_hyp_exit();				\
+		__arm_smccc_1_1(SMCCC_SMC_INST, __VA_ARGS__);	\
+		trace_hyp_enter();				\
+	} while (0)

Huh. No, please. Don't override existing kernel constructs behind
everybody's back. I know that tracing folks love to play that sort of
game, but I really don't want any of that here.

And you haven't seen what I had for arm_smccc_1_2_smc()

Just define a wrapper that is KVM-specific, and use that.

Then from a semantic perspective, an SMC call, an ERET back to EL1
host, and an ERET back to EL1 guest are all very different events that
you lump under the "exit" category. That's not right. Same thing for
"enter".

The idea of those events is just to know when we enter and exit the hypervisor,
purely from a timing point of view. In ACK, we already have other separated
events that can give the "cause" for entering or exiting the hypervisor. I
haven't added them to that series because I thought it was big enough.

So happy to add now or do a follow-up, once we're done with that one?

Thanks,

	M.

-- 
Jazz isn't dead. It just smells funny.