On 23/12/20 15:45, Dario Faggioli wrote:
From: Lorenzo Brescia <lorenzo.bres...@edu.unito.it>
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.bres...@edu.unito.it>
Signed-off-by: Dario Faggioli <dfaggi...@suse.com>
---
Cc: Paolo Bonzini <pbonz...@redhat.com>
Cc: Sean Christopherson <sea...@google.com>
Cc: Vitaly Kuznetsov <vkuzn...@redhat.com>
Cc: Wanpeng Li <wanpen...@tencent.com>
Cc: Jim Mattson <jmatt...@google.com>
Cc: Joerg Roedel <j...@8bytes.org>
Cc: k...@vger.kernel.org
Cc: Lorenzo Brescia <lorenzo.bres...@edu.unito.it>
Cc: Dario Faggioli <dfaggi...@suse.com>
---
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 cce0143a6f80..ed272fcf6495 100644
--- a/arch/x86/kvm/svm/svm.c
+++ b/arch/x86/kvm/svm/svm.c
@@ -3741,6 +3741,8 @@ 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 75c9c6a0a3a4..ff20f9e6e5b3 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -6653,6 +6653,8 @@ static fastpath_t vmx_vcpu_run(struct kvm_vcpu *vcpu)
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 3f7c1fc7a3ce..a79666204907 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -8973,8 +8973,6 @@ 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();
@@ -11538,6 +11536,7 @@ 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);
Qeuued, thanks!
Paolo
