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As a result it is also wrong for us to mark the upcall vector as > having a pending request when the vLAPIC is in this state. > > To compensate for the "enabled" check added to the assertion logic, add > logic to (conditionally) mark the upcall vector as having a request > pending at the time the LAPIC is being software-enabled by the guest. > > Fixes: 7b5b8ca7dffd ("x86/upcall: inject a spurious event after setting upcall vector") > Signed-off-by: Jan Beulich > --- > Don't one or both of the Viridian uses of vlapic_set_irq() need similar > guarding? > > Is it actually necessary for hvmop_set_evtchn_upcall_vector() and > hvm_set_callback_via() to call hvm_assert_evtchn_irq() when > evtchn_upcall_pending is false? > > --- a/xen/arch/x86/hvm/irq.c > +++ b/xen/arch/x86/hvm/irq.c > @@ -321,9 +321,10 @@ void hvm_assert_evtchn_irq(struct vcpu * > > if ( v->arch.hvm.evtchn_upcall_vector != 0 ) > { > - uint8_t vector = v->arch.hvm.evtchn_upcall_vector; > + struct vlapic *vlapic = vcpu_vlapic(v); > > - vlapic_set_irq(vcpu_vlapic(v), vector, 0); > + if ( vlapic_enabled(vlapic) ) > + vlapic_set_irq(vlapic, v->arch.hvm.evtchn_upcall_vector, 0); Shouldn't the vlapic_enabled() check itself be in vlapic_set_irq()? We certainly don't want any vectors set until the vlapic is enabled, be it event channel upcalls or any other sources. Maybe best to add an ASSERT in vlapic_set_irq() to be sure the lapic is enabled, as other callers already check this before trying to inject? Also, and not strictly related to your change, isn't this possibly racy, as by the time you evaluate the return of vlapic_enabled() it is already stale, as there's no lock to protect it from changing? Thanks, Roger.