From d95df9510679757bdfc22376d351cdf367b3a604 Mon Sep 17 00:00:00 2001 From: Lorenzo Brescia Date: Wed, 23 Dec 2020 14:45:07 +0000 Subject: [PATCH] kvm: tracing: Fix unmatched kvm_entry and kvm_exit events On VMX, if we exit and then re-enter immediately without leaving the vmx_vcpu_run() function, the kvm_entry event is not logged. That means we will see one (or more) kvm_exit, without its (their) corresponding kvm_entry, as shown here: CPU-1979 [002] 89.871187: kvm_entry: vcpu 1 CPU-1979 [002] 89.871218: kvm_exit: reason MSR_WRITE CPU-1979 [002] 89.871259: kvm_exit: reason MSR_WRITE It also seems possible for a kvm_entry event to be logged, but then we leave vmx_vcpu_run() right away (if vmx->emulation_required is true). In this case, we will have a spurious kvm_entry event in the trace. Fix these situations by moving trace_kvm_entry() inside vmx_vcpu_run() (where trace_kvm_exit() already is). A trace obtained with this patch applied looks like this: CPU-14295 [000] 8388.395387: kvm_entry: vcpu 0 CPU-14295 [000] 8388.395392: kvm_exit: reason MSR_WRITE CPU-14295 [000] 8388.395393: kvm_entry: vcpu 0 CPU-14295 [000] 8388.395503: kvm_exit: reason EXTERNAL_INTERRUPT Of course, not calling trace_kvm_entry() in common x86 code any longer means that we need to adjust the SVM side of things too. Signed-off-by: Lorenzo Brescia Signed-off-by: Dario Faggioli Message-Id: <160873470698.11652.13483635328769030605.stgit@Wayrath> Signed-off-by: Paolo Bonzini --- arch/x86/kvm/svm/svm.c | 2 ++ arch/x86/kvm/vmx/vmx.c | 2 ++ arch/x86/kvm/x86.c | 3 +-- 3 files changed, 5 insertions(+), 2 deletions(-) diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c index 7ef171790d02..f923e14e87df 100644 --- a/arch/x86/kvm/svm/svm.c +++ b/arch/x86/kvm/svm/svm.c @@ -3739,6 +3739,8 @@ static __no_kcsan fastpath_t svm_vcpu_run(struct kvm_vcpu *vcpu) { struct vcpu_svm *svm = to_svm(vcpu); + trace_kvm_entry(vcpu); + svm->vmcb->save.rax = vcpu->arch.regs[VCPU_REGS_RAX]; svm->vmcb->save.rsp = vcpu->arch.regs[VCPU_REGS_RSP]; svm->vmcb->save.rip = vcpu->arch.regs[VCPU_REGS_RIP]; diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c index 2af05d3b0590..cc60b1fc3ee7 100644 --- a/arch/x86/kvm/vmx/vmx.c +++ b/arch/x86/kvm/vmx/vmx.c @@ -6653,6 +6653,8 @@ reenter_guest: if (vmx->emulation_required) return EXIT_FASTPATH_NONE; + trace_kvm_entry(vcpu); + if (vmx->ple_window_dirty) { vmx->ple_window_dirty = false; vmcs_write32(PLE_WINDOW, vmx->ple_window); diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 9025c7673af6..1f64e8b97605 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -8992,8 +8992,6 @@ static int vcpu_enter_guest(struct kvm_vcpu *vcpu) kvm_x86_ops.request_immediate_exit(vcpu); } - trace_kvm_entry(vcpu); - fpregs_assert_state_consistent(); if (test_thread_flag(TIF_NEED_FPU_LOAD)) switch_fpu_return(); @@ -11560,6 +11558,7 @@ int kvm_sev_es_string_io(struct kvm_vcpu *vcpu, unsigned int size, } EXPORT_SYMBOL_GPL(kvm_sev_es_string_io); +EXPORT_TRACEPOINT_SYMBOL_GPL(kvm_entry); EXPORT_TRACEPOINT_SYMBOL_GPL(kvm_exit); EXPORT_TRACEPOINT_SYMBOL_GPL(kvm_fast_mmio); EXPORT_TRACEPOINT_SYMBOL_GPL(kvm_inj_virq);