xen/events: fix unmask_evtchn for PV on HVM guests
When unmask_evtchn is called, if we already have an event pending, we just set evtchn_pending_sel waiting for local_irq_enable to be called. That is because PV guests set the irq_enable pvops to xen_irq_enable_direct in xen_setup_vcpu_info_placement: xen_irq_enable_direct is implemented in assembly in arch/x86/xen/xen-asm.S and call xen_force_evtchn_callback if XEN_vcpu_info_pending is set. However HVM guests (and ARM guests) do not change or do not have the irq_enable pvop, so evtchn_unmask cannot work properly for them. Considering that having the pending_irq bit set when unmask_evtchn is called is not very common, and it is simpler to keep the native_irq_enable implementation for HVM guests (and ARM guests), the best thing to do is just use the EVTCHNOP_unmask hypercall (Xen re-injects pending events in response). Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com> Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
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@ -373,11 +373,22 @@ static void unmask_evtchn(int port)
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{
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struct shared_info *s = HYPERVISOR_shared_info;
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unsigned int cpu = get_cpu();
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int do_hypercall = 0, evtchn_pending = 0;
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BUG_ON(!irqs_disabled());
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/* Slow path (hypercall) if this is a non-local port. */
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if (unlikely(cpu != cpu_from_evtchn(port))) {
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if (unlikely((cpu != cpu_from_evtchn(port))))
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do_hypercall = 1;
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else
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evtchn_pending = sync_test_bit(port, &s->evtchn_pending[0]);
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if (unlikely(evtchn_pending && xen_hvm_domain()))
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do_hypercall = 1;
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/* Slow path (hypercall) if this is a non-local port or if this is
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* an hvm domain and an event is pending (hvm domains don't have
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* their own implementation of irq_enable). */
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if (do_hypercall) {
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struct evtchn_unmask unmask = { .port = port };
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(void)HYPERVISOR_event_channel_op(EVTCHNOP_unmask, &unmask);
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} else {
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@ -390,7 +401,7 @@ static void unmask_evtchn(int port)
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* 'hw_resend_irq'. Just like a real IO-APIC we 'lose
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* the interrupt edge' if the channel is masked.
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*/
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if (sync_test_bit(port, &s->evtchn_pending[0]) &&
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if (evtchn_pending &&
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!sync_test_and_set_bit(port / BITS_PER_LONG,
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&vcpu_info->evtchn_pending_sel))
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vcpu_info->evtchn_upcall_pending = 1;
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