File 5a4e2c2c-x86-upcall-inject-spurious-event-after-setting-vector.patch of Package xen.6649

# Commit 7b5b8ca7dffde866d851f0b87b994e0b13e5b867
# Date 2018-01-04 14:29:16 +0100
# Author Roger Pau Monné <roger.pau@citrix.com>
# Committer Jan Beulich <jbeulich@suse.com>
x86/upcall: inject a spurious event after setting upcall vector

In case the vCPU has pending events to inject. This fixes a bug that
happened if the guest mapped the vcpu info area using
VCPUOP_register_vcpu_info without having setup the event channel
upcall, and then setup the upcall vector.

In this scenario the guest would not receive any upcalls, because the
call to VCPUOP_register_vcpu_info would have marked the vCPU as having
pending events, but the vector could not be injected because it was
not yet setup.

This has not caused issues so far because all the consumers first
setup the vector callback and then map the vcpu info page, but there's
no limitation that prevents doing it in the inverse order.

Signed-off-by: Roger Pau Monné <roger.pau@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>

--- a/xen/arch/x86/hvm/hvm.c
+++ b/xen/arch/x86/hvm/hvm.c
@@ -4925,6 +4925,7 @@ static int hvmop_set_evtchn_upcall_vecto
     printk(XENLOG_G_INFO "%pv: upcall vector %02x\n", v, op.vector);
 
     v->arch.hvm_vcpu.evtchn_upcall_vector = op.vector;
+    hvm_assert_evtchn_irq(v);
     return 0;
 }
 
--- a/xen/arch/x86/hvm/irq.c
+++ b/xen/arch/x86/hvm/irq.c
@@ -324,6 +324,7 @@ void hvm_set_callback_via(struct domain
     struct hvm_irq *hvm_irq = &d->arch.hvm_domain.irq;
     unsigned int gsi=0, pdev=0, pintx=0;
     uint8_t via_type;
+    struct vcpu *v;
 
     via_type = (uint8_t)(via >> 56) + 1;
     if ( ((via_type == HVMIRQ_callback_gsi) && (via == 0)) ||
@@ -386,6 +387,10 @@ void hvm_set_callback_via(struct domain
 
     spin_unlock(&d->arch.hvm_domain.irq_lock);
 
+    for_each_vcpu ( d, v )
+        if ( is_vcpu_online(v) )
+            hvm_assert_evtchn_irq(v);
+
 #ifndef NDEBUG
     printk(XENLOG_G_INFO "Dom%u callback via changed to ", d->domain_id);
     switch ( via_type )