diff options
| author | Sean Christopherson <seanjc@google.com> | 2024-01-09 17:27:01 -0800 |
|---|---|---|
| committer | Sean Christopherson <seanjc@google.com> | 2024-02-22 16:22:36 -0800 |
| commit | e6b5d16bbd2d4c8259ad76aa33de80d561aba5f9 (patch) | |
| tree | 5adbd7861d80bf83043205c2f40f616db96780cb | |
| parent | 9c9025ea003a03f967affd690f39b4ef3452c0f5 (diff) | |
KVM: VMX: Re-enter guest in fastpath for "spurious" preemption timer exits
Re-enter the guest in the fast path if VMX preeemption timer VM-Exit was
"spurious", i.e. if KVM "soft disabled" the timer by writing -1u and by
some miracle the timer expired before any other VM-Exit occurred. This is
just an intermediate step to cleaning up the preemption timer handling,
optimizing these types of spurious VM-Exits is not interesting as they are
extremely rare/infrequent.
Link: https://lore.kernel.org/r/20240110012705.506918-3-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
| -rw-r--r-- | arch/x86/kvm/vmx/vmx.c | 11 |
1 files changed, 9 insertions, 2 deletions
diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c index e3653d11f001..a44b09e35fd6 100644 --- a/arch/x86/kvm/vmx/vmx.c +++ b/arch/x86/kvm/vmx/vmx.c @@ -5992,8 +5992,15 @@ static fastpath_t handle_fastpath_preemption_timer(struct kvm_vcpu *vcpu) { struct vcpu_vmx *vmx = to_vmx(vcpu); - if (!vmx->req_immediate_exit && - !unlikely(vmx->loaded_vmcs->hv_timer_soft_disabled)) { + /* + * In the *extremely* unlikely scenario that this is a spurious VM-Exit + * due to the timer expiring while it was "soft" disabled, just eat the + * exit and re-enter the guest. + */ + if (unlikely(vmx->loaded_vmcs->hv_timer_soft_disabled)) + return EXIT_FASTPATH_REENTER_GUEST; + + if (!vmx->req_immediate_exit) { kvm_lapic_expired_hv_timer(vcpu); return EXIT_FASTPATH_REENTER_GUEST; } |