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authorLorenzo Brescia <lorenzo.brescia@edu.unito.it>2020-12-23 14:45:07 +0000
committerPaolo Bonzini <pbonzini@redhat.com>2021-01-25 18:52:08 -0500
commitd95df9510679757bdfc22376d351cdf367b3a604 (patch)
treebc191b86ea2a8ef698470f38ccd91b4711eecd5a
parent01ead84ccd23afadebe66aea0eda002ac29ca9be (diff)
downloadlinux-d95df9510679757bdfc22376d351cdf367b3a604.tar.bz2
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 <lorenzo.brescia@edu.unito.it> Signed-off-by: Dario Faggioli <dfaggioli@suse.com> Message-Id: <160873470698.11652.13483635328769030605.stgit@Wayrath> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
-rw-r--r--arch/x86/kvm/svm/svm.c2
-rw-r--r--arch/x86/kvm/vmx/vmx.c2
-rw-r--r--arch/x86/kvm/x86.c3
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);