KVM: PPC: Book3S HV: Tracepoints for KVM HV guest interactions

This patch adds trace points in the guest entry and exit code and also
for exceptions handled by the host in kernel mode - hypercalls and page
faults. The new events are added to /sys/kernel/debug/tracing/events
under a new subsystem called kvm_hv.

Acked-by: Paul Mackerras <[email protected]>
Signed-off-by: Suresh Warrier <[email protected]>
Signed-off-by: Alexander Graf <[email protected]>

Author: Suresh E. Warrier

arch/powerpc/kvm/book3s_64_mmu_hv.c

@@ -37,6 +37,8 @@
 #include <asm/ppc-opcode.h>
 #include <asm/cputable.h>
 
+#include "trace_hv.h"
+
 /* POWER7 has 10-bit LPIDs, PPC970 has 6-bit LPIDs */
 #define MAX_LPID_970	63
 
@@ -622,6 +624,8 @@ int kvmppc_book3s_hv_page_fault(struct kvm_run *run, struct kvm_vcpu *vcpu,
 	gfn = gpa >> PAGE_SHIFT;
 	memslot = gfn_to_memslot(kvm, gfn);
 
+	trace_kvm_page_fault_enter(vcpu, hpte, memslot, ea, dsisr);
+
 	/* No memslot means it's an emulated MMIO region */
 	if (!memslot || (memslot->flags & KVM_MEMSLOT_INVALID))
 		return kvmppc_hv_emulate_mmio(run, vcpu, gpa, ea,
@@ -641,6 +645,7 @@ int kvmppc_book3s_hv_page_fault(struct kvm_run *run, struct kvm_vcpu *vcpu,
 	mmu_seq = kvm->mmu_notifier_seq;
 	smp_rmb();
 
+	ret = -EFAULT;
 	is_io = 0;
 	pfn = 0;
 	page = NULL;
@@ -664,7 +669,7 @@ int kvmppc_book3s_hv_page_fault(struct kvm_run *run, struct kvm_vcpu *vcpu,
 		}
 		up_read(&current->mm->mmap_sem);
 		if (!pfn)
-			return -EFAULT;
+			goto out_put;
 	} else {
 		page = pages[0];
 		pfn = page_to_pfn(page);
@@ -694,14 +699,14 @@ int kvmppc_book3s_hv_page_fault(struct kvm_run *run, struct kvm_vcpu *vcpu,
 		}
 	}
 
-	ret = -EFAULT;
 	if (psize > pte_size)
 		goto out_put;
 
 	/* Check WIMG vs. the actual page we're accessing */
 	if (!hpte_cache_flags_ok(r, is_io)) {
 		if (is_io)
-			return -EFAULT;
+			goto out_put;
+
 		/*
 		 * Allow guest to map emulated device memory as
 		 * uncacheable, but actually make it cacheable.
@@ -765,6 +770,8 @@ int kvmppc_book3s_hv_page_fault(struct kvm_run *run, struct kvm_vcpu *vcpu,
 		SetPageDirty(page);
 
  out_put:
+	trace_kvm_page_fault_exit(vcpu, hpte, ret);
+
 	if (page) {
 		/*
 		 * We drop pages[0] here, not page because page might

arch/powerpc/kvm/book3s_hv.c

@@ -58,6 +58,9 @@
 
 #include "book3s.h"
 
+#define CREATE_TRACE_POINTS
+#include "trace_hv.h"
+
 /* #define EXIT_DEBUG */
 /* #define EXIT_DEBUG_SIMPLE */
 /* #define EXIT_DEBUG_INT */
@@ -1730,6 +1733,7 @@ static void kvmppc_run_core(struct kvmppc_vcore *vc)
 	list_for_each_entry(vcpu, &vc->runnable_threads, arch.run_list) {
 		kvmppc_start_thread(vcpu);
 		kvmppc_create_dtl_entry(vcpu, vc);
+		trace_kvm_guest_enter(vcpu);
 	}
 
 	/* Set this explicitly in case thread 0 doesn't have a vcpu */
@@ -1738,6 +1742,9 @@ static void kvmppc_run_core(struct kvmppc_vcore *vc)
 
 	vc->vcore_state = VCORE_RUNNING;
 	preempt_disable();
+
+	trace_kvmppc_run_core(vc, 0);
+
 	spin_unlock(&vc->lock);
 
 	kvm_guest_enter();
@@ -1783,6 +1790,8 @@ static void kvmppc_run_core(struct kvmppc_vcore *vc)
 		    kvmppc_core_pending_dec(vcpu))
 			kvmppc_core_dequeue_dec(vcpu);
 
+		trace_kvm_guest_exit(vcpu);
+
 		ret = RESUME_GUEST;
 		if (vcpu->arch.trap)
 			ret = kvmppc_handle_exit_hv(vcpu->arch.kvm_run, vcpu,
@@ -1808,6 +1817,8 @@ static void kvmppc_run_core(struct kvmppc_vcore *vc)
 			wake_up(&vcpu->arch.cpu_run);
 		}
 	}
+
+	trace_kvmppc_run_core(vc, 1);
 }
 
 /*
@@ -1854,11 +1865,13 @@ static void kvmppc_vcore_blocked(struct kvmppc_vcore *vc)
 	}
 
 	vc->vcore_state = VCORE_SLEEPING;
+	trace_kvmppc_vcore_blocked(vc, 0);
 	spin_unlock(&vc->lock);
 	schedule();
 	finish_wait(&vc->wq, &wait);
 	spin_lock(&vc->lock);
 	vc->vcore_state = VCORE_INACTIVE;
+	trace_kvmppc_vcore_blocked(vc, 1);
 }
 
 static int kvmppc_run_vcpu(struct kvm_run *kvm_run, struct kvm_vcpu *vcpu)
@@ -1867,6 +1880,8 @@ static int kvmppc_run_vcpu(struct kvm_run *kvm_run, struct kvm_vcpu *vcpu)
 	struct kvmppc_vcore *vc;
 	struct kvm_vcpu *v, *vn;
 
+	trace_kvmppc_run_vcpu_enter(vcpu);
+
 	kvm_run->exit_reason = 0;
 	vcpu->arch.ret = RESUME_GUEST;
 	vcpu->arch.trap = 0;
@@ -1896,6 +1911,7 @@ static int kvmppc_run_vcpu(struct kvm_run *kvm_run, struct kvm_vcpu *vcpu)
 		    VCORE_EXIT_COUNT(vc) == 0) {
 			kvmppc_create_dtl_entry(vcpu, vc);
 			kvmppc_start_thread(vcpu);
+			trace_kvm_guest_enter(vcpu);
 		} else if (vc->vcore_state == VCORE_SLEEPING) {
 			wake_up(&vc->wq);
 		}
@@ -1960,6 +1976,7 @@ static int kvmppc_run_vcpu(struct kvm_run *kvm_run, struct kvm_vcpu *vcpu)
 		wake_up(&v->arch.cpu_run);
 	}
 
+	trace_kvmppc_run_vcpu_exit(vcpu, kvm_run);
 	spin_unlock(&vc->lock);
 	return vcpu->arch.ret;
 }
@@ -2005,7 +2022,9 @@ static int kvmppc_vcpu_run_hv(struct kvm_run *run, struct kvm_vcpu *vcpu)
 
 		if (run->exit_reason == KVM_EXIT_PAPR_HCALL &&
 		    !(vcpu->arch.shregs.msr & MSR_PR)) {
+			trace_kvm_hcall_enter(vcpu);
 			r = kvmppc_pseries_do_hcall(vcpu);
+			trace_kvm_hcall_exit(vcpu, r);
 			kvmppc_core_prepare_to_enter(vcpu);
 		} else if (r == RESUME_PAGE_FAULT) {
 			srcu_idx = srcu_read_lock(&vcpu->kvm->srcu);

arch/powerpc/kvm/trace_book3s.h

@@ -0,0 +1,32 @@
+#if !defined(_TRACE_KVM_BOOK3S_H)
+#define _TRACE_KVM_BOOK3S_H
+
+/*
+ * Common defines used by the trace macros in trace_pr.h and trace_hv.h
+ */
+
+#define kvm_trace_symbol_exit \
+	{0x100, "SYSTEM_RESET"}, \
+	{0x200, "MACHINE_CHECK"}, \
+	{0x300, "DATA_STORAGE"}, \
+	{0x380, "DATA_SEGMENT"}, \
+	{0x400, "INST_STORAGE"}, \
+	{0x480, "INST_SEGMENT"}, \
+	{0x500, "EXTERNAL"}, \
+	{0x501, "EXTERNAL_LEVEL"}, \
+	{0x502, "EXTERNAL_HV"}, \
+	{0x600, "ALIGNMENT"}, \
+	{0x700, "PROGRAM"}, \
+	{0x800, "FP_UNAVAIL"}, \
+	{0x900, "DECREMENTER"}, \
+	{0x980, "HV_DECREMENTER"}, \
+	{0xc00, "SYSCALL"}, \
+	{0xd00, "TRACE"}, \
+	{0xe00, "H_DATA_STORAGE"}, \
+	{0xe20, "H_INST_STORAGE"}, \
+	{0xe40, "H_EMUL_ASSIST"}, \
+	{0xf00, "PERFMON"}, \
+	{0xf20, "ALTIVEC"}, \
+	{0xf40, "VSX"}
+
+#endif