[PATCH v14 28/30] KVM: arm64: Add hyp_enter/hyp_exit events to nVHE/pKVM hyp

Vincent Donnefort
2026-03-09T16:26:31Z

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

Signed-off-by: Vincent Donnefort <vdonnefort@google.com>

diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
index 2ca264b3db5f..b50ac3bb4bc9 100644
--- a/arch/arm64/include/asm/kvm_host.h
+++ b/arch/arm64/include/asm/kvm_host.h
@@ -920,6 +920,9 @@ struct kvm_vcpu_arch {

/* Per-vcpu TLB for VNCR_EL2 -- NULL when !NV */
struct vncr_tlb *vncr_tlb;
+
+ /* Hyp-readable copy of kvm_vcpu::pid */
+ pid_t pid;
};

/*
diff --git a/arch/arm64/include/asm/kvm_hypevents.h b/arch/arm64/include/asm/kvm_hypevents.h
index d6e033c96c52..221a1dacb2f0 100644
--- a/arch/arm64/include/asm/kvm_hypevents.h
+++ b/arch/arm64/include/asm/kvm_hypevents.h
@@ -7,4 +7,43 @@
#include <nvhe/trace.h>
#endif

+#ifndef __HYP_ENTER_EXIT_REASON
+#define __HYP_ENTER_EXIT_REASON
+enum hyp_enter_exit_reason {
+ HYP_REASON_SMC,
+ HYP_REASON_HVC,
+ HYP_REASON_PSCI,
+ HYP_REASON_HOST_ABORT,
+ HYP_REASON_GUEST_EXIT,
+ HYP_REASON_ERET_HOST,
+ HYP_REASON_ERET_GUEST,
+ HYP_REASON_UNKNOWN /* Must be last */
+};
+#endif
+
+HYP_EVENT(hyp_enter,
+ HE_PROTO(struct kvm_cpu_context *host_ctxt, u8 reason),
+ HE_STRUCT(
+ he_field(u8, reason)
+ he_field(pid_t, vcpu)
+ ),
+ HE_ASSIGN(
+ __entry->reason = reason;
+ __entry->vcpu = __tracing_get_vcpu_pid(host_ctxt);
+ ),
+ HE_PRINTK("reason=%s vcpu=%d", __hyp_enter_exit_reason_str(__entry->reason), __entry->vcpu)
+);
+
+HYP_EVENT(hyp_exit,
+ HE_PROTO(struct kvm_cpu_context *host_ctxt, u8 reason),
+ HE_STRUCT(
+ he_field(u8, reason)
+ he_field(pid_t, vcpu)
+ ),
+ HE_ASSIGN(
+ __entry->reason = reason;
+ __entry->vcpu = __tracing_get_vcpu_pid(host_ctxt);
+ ),
+ HE_PRINTK("reason=%s vcpu=%d", __hyp_enter_exit_reason_str(__entry->reason), __entry->vcpu)
+);
#endif
diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c
index 87a3d28d5f0f..04c43c9eb764 100644
--- a/arch/arm64/kvm/arm.c
+++ b/arch/arm64/kvm/arm.c
@@ -707,6 +707,8 @@ void kvm_arch_vcpu_load(struct kvm_vcpu *vcpu, int cpu)

if (!cpumask_test_cpu(cpu, vcpu->kvm->arch.supported_cpus))
vcpu_set_on_unsupported_cpu(vcpu);
+
+ vcpu->arch.pid = pid_nr(vcpu->pid);
}

void kvm_arch_vcpu_put(struct kvm_vcpu *vcpu)
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..1258bc84477f
--- /dev/null
+++ b/arch/arm64/kvm/hyp/include/nvhe/arm-smccc.h
@@ -0,0 +1,23 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+#ifndef __ARM64_KVM_HYP_NVHE_ARM_SMCCC_H__
+#define __ARM64_KVM_HYP_NVHE_ARM_SMCCC_H__
+
+#include <asm/kvm_hypevents.h>
+
+#include <linux/arm-smccc.h>
+
+#define hyp_smccc_1_1_smc(...) \
+ do { \
+ trace_hyp_exit(NULL, HYP_REASON_SMC); \
+ arm_smccc_1_1_smc(__VA_ARGS__); \
+ trace_hyp_enter(NULL, HYP_REASON_SMC); \
+ } while (0)
+
+#define hyp_smccc_1_2_smc(...) \
+ do { \
+ trace_hyp_exit(NULL, HYP_REASON_SMC); \
+ arm_smccc_1_2_smc(__VA_ARGS__); \
+ trace_hyp_enter(NULL, HYP_REASON_SMC); \
+ } while (0)
+
+#endif /* __ARM64_KVM_HYP_NVHE_ARM_SMCCC_H__ */
diff --git a/arch/arm64/kvm/hyp/include/nvhe/trace.h b/arch/arm64/kvm/hyp/include/nvhe/trace.h
index 802a18b77c56..8813ff250f8e 100644
--- a/arch/arm64/kvm/hyp/include/nvhe/trace.h
+++ b/arch/arm64/kvm/hyp/include/nvhe/trace.h
@@ -6,6 +6,18 @@

#include <asm/kvm_hyptrace.h>

+static inline pid_t __tracing_get_vcpu_pid(struct kvm_cpu_context *host_ctxt)
+{
+ struct kvm_vcpu *vcpu;
+
+ if (!host_ctxt)
+ host_ctxt = host_data_ptr(host_ctxt);
+
+ vcpu = host_ctxt->__hyp_running_vcpu;
+
+ return vcpu ? vcpu->arch.pid : 0;
+}
+
#define HE_PROTO(__args...) __args
#define HE_ASSIGN(__args...) __args
#define HE_STRUCT RE_STRUCT
diff --git a/arch/arm64/kvm/hyp/nvhe/ffa.c b/arch/arm64/kvm/hyp/nvhe/ffa.c
index 94161ea1cd60..1af722771178 100644
--- a/arch/arm64/kvm/hyp/nvhe/ffa.c
+++ b/arch/arm64/kvm/hyp/nvhe/ffa.c
@@ -26,10 +26,10 @@
* the duration and are therefore serialised.
*/

-#include <linux/arm-smccc.h>
#include <linux/arm_ffa.h>
#include <asm/kvm_pkvm.h>

+#include <nvhe/arm-smccc.h>
#include <nvhe/ffa.h>
#include <nvhe/mem_protect.h>
#include <nvhe/memory.h>
@@ -147,7 +147,7 @@ static int ffa_map_hyp_buffers(u64 ffa_page_count)
{
struct arm_smccc_1_2_regs res;

- arm_smccc_1_2_smc(&(struct arm_smccc_1_2_regs) {
+ hyp_smccc_1_2_smc(&(struct arm_smccc_1_2_regs) {
.a0 = FFA_FN64_RXTX_MAP,
.a1 = hyp_virt_to_phys(hyp_buffers.tx),
.a2 = hyp_virt_to_phys(hyp_buffers.rx),
@@ -161,7 +161,7 @@ static int ffa_unmap_hyp_buffers(void)
{
struct arm_smccc_1_2_regs res;

- arm_smccc_1_2_smc(&(struct arm_smccc_1_2_regs) {
+ hyp_smccc_1_2_smc(&(struct arm_smccc_1_2_regs) {
.a0 = FFA_RXTX_UNMAP,
.a1 = HOST_FFA_ID,
}, &res);
@@ -172,7 +172,7 @@ static int ffa_unmap_hyp_buffers(void)
static void ffa_mem_frag_tx(struct arm_smccc_1_2_regs *res, u32 handle_lo,
u32 handle_hi, u32 fraglen, u32 endpoint_id)
{
- arm_smccc_1_2_smc(&(struct arm_smccc_1_2_regs) {
+ hyp_smccc_1_2_smc(&(struct arm_smccc_1_2_regs) {
.a0 = FFA_MEM_FRAG_TX,
.a1 = handle_lo,
.a2 = handle_hi,
@@ -184,7 +184,7 @@ static void ffa_mem_frag_tx(struct arm_smccc_1_2_regs *res, u32 handle_lo,
static void ffa_mem_frag_rx(struct arm_smccc_1_2_regs *res, u32 handle_lo,
u32 handle_hi, u32 fragoff)
{
- arm_smccc_1_2_smc(&(struct arm_smccc_1_2_regs) {
+ hyp_smccc_1_2_smc(&(struct arm_smccc_1_2_regs) {
.a0 = FFA_MEM_FRAG_RX,
.a1 = handle_lo,
.a2 = handle_hi,
@@ -196,7 +196,7 @@ static void ffa_mem_frag_rx(struct arm_smccc_1_2_regs *res, u32 handle_lo,
static void ffa_mem_xfer(struct arm_smccc_1_2_regs *res, u64 func_id, u32 len,
u32 fraglen)
{
- arm_smccc_1_2_smc(&(struct arm_smccc_1_2_regs) {
+ hyp_smccc_1_2_smc(&(struct arm_smccc_1_2_regs) {
.a0 = func_id,
.a1 = len,
.a2 = fraglen,
@@ -206,7 +206,7 @@ static void ffa_mem_xfer(struct arm_smccc_1_2_regs *res, u64 func_id, u32 len,
static void ffa_mem_reclaim(struct arm_smccc_1_2_regs *res, u32 handle_lo,
u32 handle_hi, u32 flags)
{
- arm_smccc_1_2_smc(&(struct arm_smccc_1_2_regs) {
+ hyp_smccc_1_2_smc(&(struct arm_smccc_1_2_regs) {
.a0 = FFA_MEM_RECLAIM,
.a1 = handle_lo,
.a2 = handle_hi,
@@ -216,7 +216,7 @@ static void ffa_mem_reclaim(struct arm_smccc_1_2_regs *res, u32 handle_lo,

static void ffa_retrieve_req(struct arm_smccc_1_2_regs *res, u32 len)
{
- arm_smccc_1_2_smc(&(struct arm_smccc_1_2_regs) {
+ hyp_smccc_1_2_smc(&(struct arm_smccc_1_2_regs) {
.a0 = FFA_FN64_MEM_RETRIEVE_REQ,
.a1 = len,
.a2 = len,
@@ -225,7 +225,7 @@ static void ffa_retrieve_req(struct arm_smccc_1_2_regs *res, u32 len)

static void ffa_rx_release(struct arm_smccc_1_2_regs *res)
{
- arm_smccc_1_2_smc(&(struct arm_smccc_1_2_regs) {
+ hyp_smccc_1_2_smc(&(struct arm_smccc_1_2_regs) {
.a0 = FFA_RX_RELEASE,
}, res);
}
@@ -728,7 +728,7 @@ static int hyp_ffa_post_init(void)
size_t min_rxtx_sz;
struct arm_smccc_1_2_regs res;

- arm_smccc_1_2_smc(&(struct arm_smccc_1_2_regs){
+ hyp_smccc_1_2_smc(&(struct arm_smccc_1_2_regs){
.a0 = FFA_ID_GET,
}, &res);
if (res.a0 != FFA_SUCCESS)
@@ -737,7 +737,7 @@ static int hyp_ffa_post_init(void)
if (res.a2 != HOST_FFA_ID)
return -EINVAL;

- arm_smccc_1_2_smc(&(struct arm_smccc_1_2_regs){
+ hyp_smccc_1_2_smc(&(struct arm_smccc_1_2_regs){
.a0 = FFA_FEATURES,
.a1 = FFA_FN64_RXTX_MAP,
}, &res);
@@ -788,7 +788,7 @@ static void do_ffa_version(struct arm_smccc_1_2_regs *res,
* first if TEE supports it.
*/
if (FFA_MINOR_VERSION(ffa_req_version) < FFA_MINOR_VERSION(hyp_ffa_version)) {
- arm_smccc_1_2_smc(&(struct arm_smccc_1_2_regs) {
+ hyp_smccc_1_2_smc(&(struct arm_smccc_1_2_regs) {
.a0 = FFA_VERSION,
.a1 = ffa_req_version,
}, res);
@@ -824,7 +824,7 @@ static void do_ffa_part_get(struct arm_smccc_1_2_regs *res,
goto out_unlock;
}

- arm_smccc_1_2_smc(&(struct arm_smccc_1_2_regs) {
+ hyp_smccc_1_2_smc(&(struct arm_smccc_1_2_regs) {
.a0 = FFA_PARTITION_INFO_GET,
.a1 = uuid0,
.a2 = uuid1,
@@ -939,7 +939,7 @@ int hyp_ffa_init(void *pages)
if (kvm_host_psci_config.smccc_version < ARM_SMCCC_VERSION_1_2)
return 0;

- arm_smccc_1_2_smc(&(struct arm_smccc_1_2_regs) {
+ hyp_smccc_1_2_smc(&(struct arm_smccc_1_2_regs) {
.a0 = FFA_VERSION,
.a1 = FFA_VERSION_1_2,
}, &res);
diff --git a/arch/arm64/kvm/hyp/nvhe/hyp-main.c b/arch/arm64/kvm/hyp/nvhe/hyp-main.c
index fc5953f31b4b..547d63679022 100644
--- a/arch/arm64/kvm/hyp/nvhe/hyp-main.c
+++ b/arch/arm64/kvm/hyp/nvhe/hyp-main.c
@@ -12,6 +12,7 @@
#include <asm/kvm_emulate.h>
#include <asm/kvm_host.h>
#include <asm/kvm_hyp.h>
+#include <asm/kvm_hypevents.h>
#include <asm/kvm_mmu.h>

#include <nvhe/ffa.h>
@@ -137,6 +138,8 @@ static void flush_hyp_vcpu(struct pkvm_hyp_vcpu *hyp_vcpu)
hyp_vcpu->vcpu.arch.vsesr_el2 = host_vcpu->arch.vsesr_el2;

hyp_vcpu->vcpu.arch.vgic_cpu.vgic_v3 = host_vcpu->arch.vgic_cpu.vgic_v3;
+
+ hyp_vcpu->vcpu.arch.pid = host_vcpu->arch.pid;
}

static void sync_hyp_vcpu(struct pkvm_hyp_vcpu *hyp_vcpu)
@@ -728,7 +731,9 @@ static void handle_host_hcall(struct kvm_cpu_context *host_ctxt)

static void default_host_smc_handler(struct kvm_cpu_context *host_ctxt)
{
+ trace_hyp_exit(host_ctxt, HYP_REASON_SMC);
__kvm_hyp_host_forward_smc(host_ctxt);
+ trace_hyp_enter(host_ctxt, HYP_REASON_SMC);
}

static void handle_host_smc(struct kvm_cpu_context *host_ctxt)
@@ -815,15 +820,19 @@ void handle_trap(struct kvm_cpu_context *host_ctxt)
{
u64 esr = read_sysreg_el2(SYS_ESR);

+
switch (ESR_ELx_EC(esr)) {
case ESR_ELx_EC_HVC64:
+ trace_hyp_enter(host_ctxt, HYP_REASON_HVC);
handle_host_hcall(host_ctxt);
break;
case ESR_ELx_EC_SMC64:
+ trace_hyp_enter(host_ctxt, HYP_REASON_SMC);
handle_host_smc(host_ctxt);
break;
case ESR_ELx_EC_IABT_LOW:
case ESR_ELx_EC_DABT_LOW:
+ trace_hyp_enter(host_ctxt, HYP_REASON_HOST_ABORT);
handle_host_mem_abort(host_ctxt);
break;
case ESR_ELx_EC_SYS64:
@@ -833,4 +842,6 @@ void handle_trap(struct kvm_cpu_context *host_ctxt)
default:
BUG();
}
+
+ trace_hyp_exit(host_ctxt, HYP_REASON_ERET_HOST);
}
diff --git a/arch/arm64/kvm/hyp/nvhe/psci-relay.c b/arch/arm64/kvm/hyp/nvhe/psci-relay.c
index c3e196fb8b18..ab4c7bddb163 100644
--- a/arch/arm64/kvm/hyp/nvhe/psci-relay.c
+++ b/arch/arm64/kvm/hyp/nvhe/psci-relay.c
@@ -6,11 +6,12 @@

#include <asm/kvm_asm.h>
#include <asm/kvm_hyp.h>
+#include <asm/kvm_hypevents.h>
#include <asm/kvm_mmu.h>
-#include <linux/arm-smccc.h>
#include <linux/kvm_host.h>
#include <uapi/linux/psci.h>

+#include <nvhe/arm-smccc.h>
#include <nvhe/memory.h>
#include <nvhe/trap_handler.h>

@@ -65,7 +66,7 @@ static unsigned long psci_call(unsigned long fn, unsigned long arg0,
{
struct arm_smccc_res res;

- arm_smccc_1_1_smc(fn, arg0, arg1, arg2, &res);
+ hyp_smccc_1_1_smc(fn, arg0, arg1, arg2, &res);
return res.a0;
}

@@ -206,6 +207,7 @@ asmlinkage void __noreturn __kvm_host_psci_cpu_entry(bool is_cpu_on)
struct kvm_cpu_context *host_ctxt;

host_ctxt = host_data_ptr(host_ctxt);
+ trace_hyp_enter(host_ctxt, HYP_REASON_PSCI);

if (is_cpu_on)
boot_args = this_cpu_ptr(&cpu_on_args);
@@ -221,6 +223,7 @@ asmlinkage void __noreturn __kvm_host_psci_cpu_entry(bool is_cpu_on)
write_sysreg_el1(INIT_SCTLR_EL1_MMU_OFF, SYS_SCTLR);
write_sysreg(INIT_PSTATE_EL1, SPSR_EL2);

+ trace_hyp_exit(host_ctxt, HYP_REASON_PSCI);
__host_enter(host_ctxt);
}

diff --git a/arch/arm64/kvm/hyp/nvhe/switch.c b/arch/arm64/kvm/hyp/nvhe/switch.c
index 779089e42681..ca60721501d1 100644
--- a/arch/arm64/kvm/hyp/nvhe/switch.c
+++ b/arch/arm64/kvm/hyp/nvhe/switch.c
@@ -7,7 +7,6 @@
#include <hyp/switch.h>
#include <hyp/sysreg-sr.h>

-#include <linux/arm-smccc.h>
#include <linux/kvm_host.h>
#include <linux/types.h>
#include <linux/jump_label.h>
@@ -21,6 +20,7 @@
#include <asm/kvm_asm.h>
#include <asm/kvm_emulate.h>
#include <asm/kvm_hyp.h>
+#include <asm/kvm_hypevents.h>
#include <asm/kvm_mmu.h>
#include <asm/fpsimd.h>
#include <asm/debug-monitors.h>
@@ -308,10 +308,13 @@ int __kvm_vcpu_run(struct kvm_vcpu *vcpu)
__debug_switch_to_guest(vcpu);

do {
+ trace_hyp_exit(host_ctxt, HYP_REASON_ERET_GUEST);
+
/* Jump in the fire! */
exit_code = __guest_enter(vcpu);

/* And we're baaack! */
+ trace_hyp_enter(host_ctxt, HYP_REASON_GUEST_EXIT);
} while (fixup_guest_exit(vcpu, &exit_code));

__sysreg_save_state_nvhe(guest_ctxt);
diff --git a/arch/arm64/kvm/hyp_trace.c b/arch/arm64/kvm/hyp_trace.c
index 0144cd26703e..1ad6a55ba95c 100644
--- a/arch/arm64/kvm/hyp_trace.c
+++ b/arch/arm64/kvm/hyp_trace.c
@@ -364,8 +364,26 @@ static struct trace_remote_callbacks trace_remote_callbacks = {
.enable_event = hyp_trace_enable_event,
};

+static const char *__hyp_enter_exit_reason_str(u8 reason);
+
#include <asm/kvm_define_hypevents.h>

+static const char *__hyp_enter_exit_reason_str(u8 reason)
+{
+ static const char strs[][12] = {
+ "smc",
+ "hvc",
+ "psci",
+ "host_abort",
+ "guest_exit",
+ "eret_host",
+ "eret_guest",
+ "unknown",
+ };
+
+ return strs[min(reason, HYP_REASON_UNKNOWN)];
+}
+
static void __init hyp_trace_init_events(void)
{
struct hyp_event_id *hyp_event_id = __hyp_event_ids_start;
--
2.53.0.473.g4a7958ca14-goog