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

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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>
This commit is contained in:
Sean Christopherson 2024-01-09 17:27:00 -08:00
parent 2a5f091ce1
commit 9c9025ea00
5 changed files with 14 additions and 9 deletions
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3
arch/x86/include/asm/kvm_host.h
View File

@ -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);

5
arch/x86/kvm/svm/svm.c
View File

@ -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];

9
arch/x86/kvm/trace.h
View File

@ -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]" : "")
);
/*

4
arch/x86/kvm/vmx/vmx.c
View File

@ -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;

2
arch/x86/kvm/x86.c
View File

@ -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;