KVM: arm/arm64: Count guest exit due to various reasons

It would add guest exit statistics to debugfs, this can be helpful
while measuring KVM performance.

  [ Renamed some of the field names - Christoffer ]
Signed-off-by: Amit Singh Tomar <amittomer25@gmail.com>
Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org>

arch/arm/include/asm/kvm_host.h

@@ -150,6 +150,12 @@ struct kvm_vcpu_stat {
 	u32 halt_successful_poll;
 	u32 halt_attempted_poll;
 	u32 halt_wakeup;
+	u32 hvc_exit_stat;
+	u64 wfe_exit_stat;
+	u64 wfi_exit_stat;
+	u64 mmio_exit_user;
+	u64 mmio_exit_kernel;
+	u64 exits;
 };
 
 int kvm_vcpu_preferred_target(struct kvm_vcpu_init *init);

arch/arm/kvm/arm.c

@@ -603,6 +603,7 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu, struct kvm_run *run)
 		ret = kvm_call_hyp(__kvm_vcpu_run, vcpu);
 
 		vcpu->mode = OUTSIDE_GUEST_MODE;
+		vcpu->stat.exits++;
 		/*
 		 * Back from guest
 		 *************************************************************/

arch/arm/kvm/guest.c

@@ -33,6 +33,12 @@
 #define VCPU_STAT(x) { #x, offsetof(struct kvm_vcpu, stat.x), KVM_STAT_VCPU }
 
 struct kvm_stats_debugfs_item debugfs_entries[] = {
+	VCPU_STAT(hvc_exit_stat),
+	VCPU_STAT(wfe_exit_stat),
+	VCPU_STAT(wfi_exit_stat),
+	VCPU_STAT(mmio_exit_user),
+	VCPU_STAT(mmio_exit_kernel),
+	VCPU_STAT(exits),
 	{ NULL }
 };
 

arch/arm/kvm/handle_exit.c

@@ -42,6 +42,7 @@ static int handle_hvc(struct kvm_vcpu *vcpu, struct kvm_run *run)
 
 	trace_kvm_hvc(*vcpu_pc(vcpu), *vcpu_reg(vcpu, 0),
 		      kvm_vcpu_hvc_get_imm(vcpu));
+	vcpu->stat.hvc_exit_stat++;
 
 	ret = kvm_psci_call(vcpu);
 	if (ret < 0) {
@@ -89,9 +90,11 @@ static int kvm_handle_wfx(struct kvm_vcpu *vcpu, struct kvm_run *run)
 {
 	if (kvm_vcpu_get_hsr(vcpu) & HSR_WFI_IS_WFE) {
 		trace_kvm_wfx(*vcpu_pc(vcpu), true);
+		vcpu->stat.wfe_exit_stat++;
 		kvm_vcpu_on_spin(vcpu);
 	} else {
 		trace_kvm_wfx(*vcpu_pc(vcpu), false);
+		vcpu->stat.wfi_exit_stat++;
 		kvm_vcpu_block(vcpu);
 	}
 

arch/arm/kvm/mmio.c

@@ -210,8 +210,11 @@ int io_mem_abort(struct kvm_vcpu *vcpu, struct kvm_run *run,
 
 	if (!ret) {
 		/* We handled the access successfully in the kernel. */
+		vcpu->stat.mmio_exit_kernel++;
 		kvm_handle_mmio_return(vcpu, run);
 		return 1;
+	} else {
+		vcpu->stat.mmio_exit_user++;
 	}
 
 	run->exit_reason	= KVM_EXIT_MMIO;

arch/arm64/include/asm/kvm_host.h

@@ -197,6 +197,12 @@ struct kvm_vcpu_stat {
 	u32 halt_successful_poll;
 	u32 halt_attempted_poll;
 	u32 halt_wakeup;
+	u32 hvc_exit_stat;
+	u64 wfe_exit_stat;
+	u64 wfi_exit_stat;
+	u64 mmio_exit_user;
+	u64 mmio_exit_kernel;
+	u64 exits;
 };
 
 int kvm_vcpu_preferred_target(struct kvm_vcpu_init *init);

arch/arm64/kvm/guest.c

@@ -34,7 +34,16 @@
 
 #include "trace.h"
 
+#define VM_STAT(x) { #x, offsetof(struct kvm, stat.x), KVM_STAT_VM }
+#define VCPU_STAT(x) { #x, offsetof(struct kvm_vcpu, stat.x), KVM_STAT_VCPU }
+
 struct kvm_stats_debugfs_item debugfs_entries[] = {
+	VCPU_STAT(hvc_exit_stat),
+	VCPU_STAT(wfe_exit_stat),
+	VCPU_STAT(wfi_exit_stat),
+	VCPU_STAT(mmio_exit_user),
+	VCPU_STAT(mmio_exit_kernel),
+	VCPU_STAT(exits),
 	{ NULL }
 };
 

arch/arm64/kvm/handle_exit.c

@@ -39,6 +39,7 @@ static int handle_hvc(struct kvm_vcpu *vcpu, struct kvm_run *run)
 
 	trace_kvm_hvc_arm64(*vcpu_pc(vcpu), vcpu_get_reg(vcpu, 0),
 			    kvm_vcpu_hvc_get_imm(vcpu));
+	vcpu->stat.hvc_exit_stat++;
 
 	ret = kvm_psci_call(vcpu);
 	if (ret < 0) {
@@ -71,9 +72,11 @@ static int kvm_handle_wfx(struct kvm_vcpu *vcpu, struct kvm_run *run)
 {
 	if (kvm_vcpu_get_hsr(vcpu) & ESR_ELx_WFx_ISS_WFE) {
 		trace_kvm_wfx_arm64(*vcpu_pc(vcpu), true);
+		vcpu->stat.wfe_exit_stat++;
 		kvm_vcpu_on_spin(vcpu);
 	} else {
 		trace_kvm_wfx_arm64(*vcpu_pc(vcpu), false);
+		vcpu->stat.wfi_exit_stat++;
 		kvm_vcpu_block(vcpu);
 	}