KVM: x86: Plumb "force_immediate_exit" into kvm_entry() tracepoint

Annotate the kvm_entry() tracepoint with "immediate exit" when KVM is
forcing a VM-Exit immediately after VM-Enter, e.g. when KVM wants to
inject an event but needs to first complete some other operation.
Knowing that KVM is (or isn't) forcing an exit is useful information when
debugging issues related to event injection.

Suggested-by: Maxim Levitsky <mlevitsk@redhat.com>
Link: https://lore.kernel.org/r/20240110012705.506918-2-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 7a59043a6ab067945ac7c2916e80ebfceae7a94b..bdda3edddec93b2d2a932226059c1b7344722908 100644 (file)
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -1663,7 +1663,8 @@ struct kvm_x86_ops {
        void (*flush_tlb_guest)(struct kvm_vcpu *vcpu);
 
        int (*vcpu_pre_run)(struct kvm_vcpu *vcpu);
-       enum exit_fastpath_completion (*vcpu_run)(struct kvm_vcpu *vcpu);
+       enum exit_fastpath_completion (*vcpu_run)(struct kvm_vcpu *vcpu,
+                                                 bool force_immediate_exit);
        int (*handle_exit)(struct kvm_vcpu *vcpu,
                enum exit_fastpath_completion exit_fastpath);
        int (*skip_emulated_instruction)(struct kvm_vcpu *vcpu);

diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
index dda91f7cd71b5ac335a29fa485d6ef3965c67990..ab8ad8d0e818070e8e886df0b7aac982b337f880 100644 (file)
--- a/arch/x86/kvm/svm/svm.c
+++ b/arch/x86/kvm/svm/svm.c
@@ -4112,12 +4112,13 @@ static noinstr void svm_vcpu_enter_exit(struct kvm_vcpu *vcpu, bool spec_ctrl_in
        guest_state_exit_irqoff();
 }
 
-static __no_kcsan fastpath_t svm_vcpu_run(struct kvm_vcpu *vcpu)
+static __no_kcsan fastpath_t svm_vcpu_run(struct kvm_vcpu *vcpu,
+                                         bool force_immediate_exit)
 {
        struct vcpu_svm *svm = to_svm(vcpu);
        bool spec_ctrl_intercepted = msr_write_intercepted(vcpu, MSR_IA32_SPEC_CTRL);
 
-       trace_kvm_entry(vcpu);
+       trace_kvm_entry(vcpu, force_immediate_exit);
 
        svm->vmcb->save.rax = vcpu->arch.regs[VCPU_REGS_RAX];
        svm->vmcb->save.rsp = vcpu->arch.regs[VCPU_REGS_RSP];

diff --git a/arch/x86/kvm/trace.h b/arch/x86/kvm/trace.h
index 83843379813ee3ef8cca33d1986ef61ea6e1ff9b..88659de4d2a7141a6eff8adb28054c8cb0a6c3c2 100644 (file)
--- a/arch/x86/kvm/trace.h
+++ b/arch/x86/kvm/trace.h
@@ -15,20 +15,23 @@
  * Tracepoint for guest mode entry.
  */
 TRACE_EVENT(kvm_entry,
-       TP_PROTO(struct kvm_vcpu *vcpu),
-       TP_ARGS(vcpu),
+       TP_PROTO(struct kvm_vcpu *vcpu, bool force_immediate_exit),
+       TP_ARGS(vcpu, force_immediate_exit),
 
        TP_STRUCT__entry(
                __field(        unsigned int,   vcpu_id         )
                __field(        unsigned long,  rip             )
+               __field(        bool,           immediate_exit  )
        ),
 
        TP_fast_assign(
                __entry->vcpu_id        = vcpu->vcpu_id;
                __entry->rip            = kvm_rip_read(vcpu);
+               __entry->immediate_exit = force_immediate_exit;
        ),
 
-       TP_printk("vcpu %u, rip 0x%lx", __entry->vcpu_id, __entry->rip)
+       TP_printk("vcpu %u, rip 0x%lx%s", __entry->vcpu_id, __entry->rip,
+                 __entry->immediate_exit ? "[immediate exit]" : "")
 );
 
 /*

diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index aa47433d0c9b6007ea5b02beaf7a8a50547aad30..e3653d11f00156d3685d2282f611dad580a0ab00 100644 (file)
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -7265,7 +7265,7 @@ out:
        guest_state_exit_irqoff();
 }
 
-static fastpath_t vmx_vcpu_run(struct kvm_vcpu *vcpu)
+static fastpath_t vmx_vcpu_run(struct kvm_vcpu *vcpu, bool force_immediate_exit)
 {
        struct vcpu_vmx *vmx = to_vmx(vcpu);
        unsigned long cr3, cr4;
@@ -7292,7 +7292,7 @@ static fastpath_t vmx_vcpu_run(struct kvm_vcpu *vcpu)
                return EXIT_FASTPATH_NONE;
        }
 
-       trace_kvm_entry(vcpu);
+       trace_kvm_entry(vcpu, force_immediate_exit);
 
        if (vmx->ple_window_dirty) {
                vmx->ple_window_dirty = false;

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index f97e443ce85356ff52512496a4dd473d778e229b..e92f14b9d0d657f0957250ac9eefec38e095e74d 100644 (file)
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -10956,7 +10956,7 @@ static int vcpu_enter_guest(struct kvm_vcpu *vcpu)
                WARN_ON_ONCE((kvm_vcpu_apicv_activated(vcpu) != kvm_vcpu_apicv_active(vcpu)) &&
                             (kvm_get_apic_mode(vcpu) != LAPIC_MODE_DISABLED));
 
-               exit_fastpath = static_call(kvm_x86_vcpu_run)(vcpu);
+               exit_fastpath = static_call(kvm_x86_vcpu_run)(vcpu, req_immediate_exit);
                if (likely(exit_fastpath != EXIT_FASTPATH_REENTER_GUEST))
                        break;