[PATCH 2/7] KVM: x86: Read guest RIP from within the kvm_nested_vmexit tracepoint

Sean Christopherson
2020-07-18T06:39:31Z

Use kvm_rip_read() to read the guest's RIP for the nested VM-Exit
tracepoint instead of having the caller pass in the tracepoint. Params
that are passed into a tracepoint are evaluated even if the tracepoint
is disabled, i.e. passing in RIP for VMX incurs a VMREAD and retpoline
to retrieve a value that may never be used, e.g. if the exit is due to a
hardware interrupt.

Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
---
arch/x86/kvm/svm/svm.c | 2 +-
arch/x86/kvm/trace.h | 6 +++---
arch/x86/kvm/vmx/nested.c | 2 +-
3 files changed, 5 insertions(+), 5 deletions(-)

diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
index 783330d0e7b88..1fea39ff33077 100644
--- a/arch/x86/kvm/svm/svm.c
+++ b/arch/x86/kvm/svm/svm.c
@@ -2943,7 +2943,7 @@ static int handle_exit(struct kvm_vcpu *vcpu, fastpath_t exit_fastpath)
if (is_guest_mode(vcpu)) {
int vmexit;

- trace_kvm_nested_vmexit(svm->vmcb->save.rip, exit_code,
+ trace_kvm_nested_vmexit(vcpu, exit_code,
svm->vmcb->control.exit_info_1,
svm->vmcb->control.exit_info_2,
svm->vmcb->control.exit_int_info,
diff --git a/arch/x86/kvm/trace.h b/arch/x86/kvm/trace.h
index 9899ff0fa2534..00e567378ae1f 100644
--- a/arch/x86/kvm/trace.h
+++ b/arch/x86/kvm/trace.h
@@ -571,10 +571,10 @@ TRACE_EVENT(kvm_nested_intercepts,
* Tracepoint for #VMEXIT while nested
*/
TRACE_EVENT(kvm_nested_vmexit,
- TP_PROTO(__u64 rip, __u32 exit_code,
+ TP_PROTO(struct kvm_vcpu *vcpu, __u32 exit_code,
__u64 exit_info1, __u64 exit_info2,
__u32 exit_int_info, __u32 exit_int_info_err, __u32 isa),
- TP_ARGS(rip, exit_code, exit_info1, exit_info2,
+ TP_ARGS(vcpu, exit_code, exit_info1, exit_info2,
exit_int_info, exit_int_info_err, isa),

TP_STRUCT__entry(
@@ -588,7 +588,7 @@ TRACE_EVENT(kvm_nested_vmexit,
),

TP_fast_assign(
- __entry->rip = rip;
+ __entry->rip = kvm_rip_read(vcpu);
__entry->exit_code = exit_code;
__entry->exit_info1 = exit_info1;
__entry->exit_info2 = exit_info2;
diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c
index 4d561edf6f9ca..6f81097cbc794 100644
--- a/arch/x86/kvm/vmx/nested.c
+++ b/arch/x86/kvm/vmx/nested.c
@@ -5912,7 +5912,7 @@ bool nested_vmx_reflect_vmexit(struct kvm_vcpu *vcpu)
exit_intr_info = vmx_get_intr_info(vcpu);
exit_qual = vmx_get_exit_qual(vcpu);

- trace_kvm_nested_vmexit(kvm_rip_read(vcpu), exit_reason, exit_qual,
+ trace_kvm_nested_vmexit(vcpu, exit_reason, exit_qual,
vmx->idt_vectoring_info, exit_intr_info,
vmcs_read32(VM_EXIT_INTR_ERROR_CODE),
KVM_ISA_VMX);
--
2.26.0