[PATCH v1 3/5] arm64: KVM: Add interface to set guest value for TRFCR register

[James Clark]

Add an interface for the Coresight driver to use to set the value of the
TRFCR register for the guest. This register controls the exclude
settings for trace at different exception levels, and is used to
honor the exclude_host and exclude_guest parameters from the Perf
session. This will be used to later write TRFCR_EL1 on nVHE at guest
switch. For VHE, TRFCR_EL1 is written immediately. Because guest writes
to the register are trapped, the value will persist and can't be
modified.

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.

Now that both guest and host values are saved, rename trfcr_el1 to
host_trfcr_el1 to make it clear that's the value that should be restored
on return to the host.

Reviewed-by: Mark Brown <broonie@xxxxxxxxxx> (sysreg)
Signed-off-by: James Clark <james.clark@xxxxxxx>
---
 arch/arm64/include/asm/kvm_host.h  |  6 +++++-
 arch/arm64/kvm/arm.c               |  1 +
 arch/arm64/kvm/debug.c             | 21 +++++++++++++++++++++
 arch/arm64/kvm/hyp/nvhe/debug-sr.c |  4 ++--
 arch/arm64/tools/sysreg            |  4 ++++
 5 files changed, 33 insertions(+), 3 deletions(-)

diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
index 498f922f4f41..0e57827a0cf2 100644
--- a/arch/arm64/include/asm/kvm_host.h
+++ b/arch/arm64/include/asm/kvm_host.h
@@ -547,7 +547,8 @@ struct kvm_vcpu_arch {
 		/* Statistical profiling extension */
 		u64 pmscr_el1;
 		/* Self-hosted trace */
-		u64 trfcr_el1;
+		u64 host_trfcr_el1;
+		u64 guest_trfcr_el1;
 	} host_debug_state;
 
 	/* VGIC state */
@@ -1097,6 +1098,8 @@ 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_etm_set_guest_trfcr(u64 trfcr_guest);
+void kvm_etm_update_vcpu_events(struct kvm_vcpu *vcpu);
 #else
 static inline void kvm_set_pmu_events(u32 set, struct perf_event_attr *attr) {}
 static inline void kvm_clr_pmu_events(u32 clr) {}
@@ -1104,6 +1107,7 @@ static inline bool kvm_set_pmuserenr(u64 val)
 {
 	return false;
 }
+static inline void kvm_etm_set_guest_trfcr(u64 trfcr_guest) {}
 #endif
 
 void kvm_vcpu_load_sysregs_vhe(struct kvm_vcpu *vcpu);
diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c
index 1bfdd583b261..65e805dc1d7a 100644
--- a/arch/arm64/kvm/arm.c
+++ b/arch/arm64/kvm/arm.c
@@ -958,6 +958,7 @@ 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/debug.c b/arch/arm64/kvm/debug.c
index 6a1bad1a921b..379d2677961f 100644
--- a/arch/arm64/kvm/debug.c
+++ b/arch/arm64/kvm/debug.c
@@ -22,6 +22,7 @@
 				DBG_MDSCR_MDE)
 
 static DEFINE_PER_CPU(u64, mdcr_el2);
+static DEFINE_PER_CPU(u64, guest_trfcr);
 
 /**
  * save/restore_guest_debug_regs
@@ -342,3 +343,23 @@ void kvm_arch_vcpu_put_debug_state_flags(struct kvm_vcpu *vcpu)
 	vcpu_clear_flag(vcpu, DEBUG_STATE_SAVE_SPE);
 	vcpu_clear_flag(vcpu, DEBUG_STATE_SAVE_TRFCR);
 }
+
+void kvm_etm_set_guest_trfcr(u64 trfcr_guest)
+{
+	if (has_vhe())
+		write_sysreg_s(trfcr_guest, SYS_TRFCR_EL12);
+	else
+		*this_cpu_ptr(&guest_trfcr) = trfcr_guest;
+}
+EXPORT_SYMBOL_GPL(kvm_etm_set_guest_trfcr);
+
+/*
+ * 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.
+ */
+void kvm_etm_update_vcpu_events(struct kvm_vcpu *vcpu)
+{
+	if (!has_vhe() && vcpu_get_flag(vcpu, DEBUG_STATE_SAVE_TRFCR))
+		vcpu->arch.host_debug_state.guest_trfcr_el1 = *this_cpu_ptr(&guest_trfcr);
+}
diff --git a/arch/arm64/kvm/hyp/nvhe/debug-sr.c b/arch/arm64/kvm/hyp/nvhe/debug-sr.c
index 89c208112eb7..55bc01e9808f 100644
--- a/arch/arm64/kvm/hyp/nvhe/debug-sr.c
+++ b/arch/arm64/kvm/hyp/nvhe/debug-sr.c
@@ -86,7 +86,7 @@ void __debug_save_host_buffers_nvhe(struct kvm_vcpu *vcpu)
 		__debug_save_spe(&vcpu->arch.host_debug_state.pmscr_el1);
 	/* Disable and flush Self-Hosted Trace generation */
 	if (vcpu_get_flag(vcpu, DEBUG_STATE_SAVE_TRFCR))
-		__debug_save_trace(&vcpu->arch.host_debug_state.trfcr_el1);
+		__debug_save_trace(&vcpu->arch.host_debug_state.host_trfcr_el1);
 }
 
 void __debug_switch_to_guest(struct kvm_vcpu *vcpu)
@@ -99,7 +99,7 @@ void __debug_restore_host_buffers_nvhe(struct kvm_vcpu *vcpu)
 	if (vcpu_get_flag(vcpu, DEBUG_STATE_SAVE_SPE))
 		__debug_restore_spe(vcpu->arch.host_debug_state.pmscr_el1);
 	if (vcpu_get_flag(vcpu, DEBUG_STATE_SAVE_TRFCR))
-		__debug_restore_trace(vcpu->arch.host_debug_state.trfcr_el1);
+		__debug_restore_trace(vcpu->arch.host_debug_state.host_trfcr_el1);
 }
 
 void __debug_switch_to_host(struct kvm_vcpu *vcpu)
diff --git a/arch/arm64/tools/sysreg b/arch/arm64/tools/sysreg
index 992722c0c23b..295a4a625b8b 100644
--- a/arch/arm64/tools/sysreg
+++ b/arch/arm64/tools/sysreg
@@ -2661,3 +2661,7 @@ EndSysreg
 Sysreg	TRFCR_EL2	3	4	1	2	1
 Fields	TRFCR_EL2
 EndSysreg
+
+Sysreg TRFCR_EL12	3	5	1	2	1
+Fields	TRFCR_ELx
+EndSysreg
-- 
2.34.1