[RFC PATCH 1/3] arm64: KVM: Add support for exclude_guest and exclude_host for ETM
From: James Clark
Date: Fri Aug 04 2023 - 06:14:32 EST
Add an interface for the Coresight driver to use to set the current
exclude settings for the current CPU. This will be used to configure
TRFCR_EL1.
The settings must be copied to the vCPU before each run in the same
way that PMU events are because the per-cpu struct isn't accessible in
protected mode.
This is only needed for nVHE, otherwise it works automatically with
TRFCR_EL{1,2}. Unfortunately it can't be gated on CONFIG_CORESIGHT
because Coresight can be built as a module. It can however be gated on
CONFIG_PERF_EVENTS because that is required by Coresight.
Signed-off-by: James Clark <james.clark@xxxxxxx>
---
arch/arm64/include/asm/kvm_host.h | 10 ++++++-
arch/arm64/kvm/Makefile | 1 +
arch/arm64/kvm/arm.c | 1 +
arch/arm64/kvm/etm.c | 48 +++++++++++++++++++++++++++++++
include/kvm/etm.h | 43 +++++++++++++++++++++++++++
5 files changed, 102 insertions(+), 1 deletion(-)
create mode 100644 arch/arm64/kvm/etm.c
create mode 100644 include/kvm/etm.h
diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
index d7b1403a3fb2..f33262217c84 100644
--- a/arch/arm64/include/asm/kvm_host.h
+++ b/arch/arm64/include/asm/kvm_host.h
@@ -35,6 +35,7 @@
#include <kvm/arm_vgic.h>
#include <kvm/arm_arch_timer.h>
#include <kvm/arm_pmu.h>
+#include <kvm/etm.h>
#define KVM_MAX_VCPUS VGIC_V3_MAX_CPUS
@@ -500,7 +501,7 @@ struct kvm_vcpu_arch {
u8 cflags;
/* Input flags to the hypervisor code, potentially cleared after use */
- u8 iflags;
+ u16 iflags;
/* State flags for kernel bookkeeping, unused by the hypervisor code */
u8 sflags;
@@ -541,6 +542,9 @@ struct kvm_vcpu_arch {
u64 pmscr_el1;
/* Self-hosted trace */
u64 trfcr_el1;
+ /* exclude_guest settings for nVHE */
+ struct kvm_etm_event etm_event;
+
} host_debug_state;
/* VGIC state */
@@ -713,6 +717,8 @@ struct kvm_vcpu_arch {
#define DEBUG_STATE_SAVE_TRBE __vcpu_single_flag(iflags, BIT(6))
/* vcpu running in HYP context */
#define VCPU_HYP_CONTEXT __vcpu_single_flag(iflags, BIT(7))
+/* Save TRFCR and apply exclude_guest rules */
+#define DEBUG_STATE_SAVE_TRFCR __vcpu_single_flag(iflags, BIT(8))
/* SVE enabled for host EL0 */
#define HOST_SVE_ENABLED __vcpu_single_flag(sflags, BIT(0))
@@ -1096,6 +1102,8 @@ void kvm_arch_vcpu_put_debug_state_flags(struct kvm_vcpu *vcpu);
void kvm_set_pmu_events(u32 set, struct perf_event_attr *attr);
void kvm_clr_pmu_events(u32 clr);
bool kvm_set_pmuserenr(u64 val);
+void kvm_set_etm_events(struct perf_event_attr *attr);
+void kvm_clr_etm_events(void);
#else
static inline void kvm_set_pmu_events(u32 set, struct perf_event_attr *attr) {}
static inline void kvm_clr_pmu_events(u32 clr) {}
diff --git a/arch/arm64/kvm/Makefile b/arch/arm64/kvm/Makefile
index c0c050e53157..0faff57423c4 100644
--- a/arch/arm64/kvm/Makefile
+++ b/arch/arm64/kvm/Makefile
@@ -23,6 +23,7 @@ kvm-y += arm.o mmu.o mmio.o psci.o hypercalls.o pvtime.o \
vgic/vgic-its.o vgic/vgic-debug.o
kvm-$(CONFIG_HW_PERF_EVENTS) += pmu-emul.o pmu.o
+kvm-$(CONFIG_PERF_EVENTS) += etm.o
always-y := hyp_constants.h hyp-constants.s
diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c
index b1a9d47fb2f3..7bd5975328a3 100644
--- a/arch/arm64/kvm/arm.c
+++ b/arch/arm64/kvm/arm.c
@@ -952,6 +952,7 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu)
kvm_vgic_flush_hwstate(vcpu);
kvm_pmu_update_vcpu_events(vcpu);
+ kvm_etm_update_vcpu_events(vcpu);
/*
* Ensure we set mode to IN_GUEST_MODE after we disable
diff --git a/arch/arm64/kvm/etm.c b/arch/arm64/kvm/etm.c
new file mode 100644
index 000000000000..359c37745de2
--- /dev/null
+++ b/arch/arm64/kvm/etm.c
@@ -0,0 +1,48 @@
+// SPDX-License-Identifier: GPL-2.0-only
+
+#include <linux/kvm_host.h>
+
+#include <kvm/etm.h>
+
+static DEFINE_PER_CPU(struct kvm_etm_event, kvm_etm_events);
+
+struct kvm_etm_event *kvm_get_etm_event(void)
+{
+ return this_cpu_ptr(&kvm_etm_events);
+}
+
+void kvm_etm_set_events(struct perf_event_attr *attr)
+{
+ struct kvm_etm_event *etm_event;
+
+ /*
+ * Exclude guest option only requires extra work with nVHE.
+ * Otherwise it works automatically with TRFCR_EL{1,2}
+ */
+ if (has_vhe())
+ return;
+
+ etm_event = kvm_get_etm_event();
+
+ etm_event->exclude_guest = attr->exclude_guest;
+ etm_event->exclude_host = attr->exclude_host;
+ etm_event->exclude_kernel = attr->exclude_kernel;
+ etm_event->exclude_user = attr->exclude_user;
+}
+EXPORT_SYMBOL_GPL(kvm_etm_set_events);
+
+void kvm_etm_clr_events(void)
+{
+ struct kvm_etm_event *etm_event;
+
+ if (has_vhe())
+ return;
+
+ etm_event = kvm_get_etm_event();
+
+ etm_event->exclude_guest = false;
+ etm_event->exclude_host = false;
+ etm_event->exclude_kernel = false;
+ etm_event->exclude_user = false;
+}
+EXPORT_SYMBOL_GPL(kvm_etm_clr_events);
diff --git a/include/kvm/etm.h b/include/kvm/etm.h
new file mode 100644
index 000000000000..95c4809fa2b0
--- /dev/null
+++ b/include/kvm/etm.h
@@ -0,0 +1,43 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+
+#ifndef __KVM_DEBUG_H
+#define __KVM_DEBUG_H
+
+struct perf_event_attr;
+struct kvm_vcpu;
+
+#if IS_ENABLED(CONFIG_KVM) && IS_ENABLED(CONFIG_PERF_EVENTS)
+
+struct kvm_etm_event {
+ bool exclude_host;
+ bool exclude_guest;
+ bool exclude_kernel;
+ bool exclude_user;
+};
+
+struct kvm_etm_event *kvm_get_etm_event(void);
+void kvm_etm_clr_events(void);
+void kvm_etm_set_events(struct perf_event_attr *attr);
+
+/*
+ * Updates the vcpu's view of the etm events for this cpu. Must be
+ * called before every vcpu run after disabling interrupts, to ensure
+ * that an interrupt cannot fire and update the structure.
+ */
+#define kvm_etm_update_vcpu_events(vcpu) \
+ do { \
+ if (!has_vhe() && vcpu_get_flag(vcpu, DEBUG_STATE_SAVE_TRFCR)) \
+ vcpu->arch.host_debug_state.etm_event = *kvm_get_etm_event(); \
+ } while (0)
+
+#else
+
+struct kvm_etm_event {};
+
+static inline void kvm_etm_update_vcpu_events(struct kvm_vcpu *vcpu) {}
+static inline void kvm_etm_set_events(struct perf_event_attr *attr) {}
+static inline void kvm_etm_clr_events(void) {}
+
+#endif
+
+#endif
--
2.34.1