[Xen-changelog] [xen stable-4.10] x86/upcall: inject a spurious event after setting upcall vector

[patchbot@xxxxxxx]

commit 69e302e59cfd281449eafb6193476a11a1c286df
Author:     Roger Pau Monné <roger.pau@xxxxxxxxxx>
AuthorDate: Thu Jan 11 17:51:14 2018 +0000
Commit:     Roger Pau Monne <roger.pau@xxxxxxxxxx>
CommitDate: Thu Jan 11 17:51:14 2018 +0000

    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@xxxxxxxxxx>
    Reviewed-by: Jan Beulich <jbeulich@xxxxxxxx>
---
 xen/arch/x86/hvm/hvm.c | 1 +
 xen/arch/x86/hvm/irq.c | 5 +++++
 2 files changed, 6 insertions(+)

diff --git a/xen/arch/x86/hvm/hvm.c b/xen/arch/x86/hvm/hvm.c
index 28bc7e4252..9f7b096072 100644
--- a/xen/arch/x86/hvm/hvm.c
+++ b/xen/arch/x86/hvm/hvm.c
@@ -4069,6 +4069,7 @@ static int hvmop_set_evtchn_upcall_vector(
     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;
 }
 
diff --git a/xen/arch/x86/hvm/irq.c b/xen/arch/x86/hvm/irq.c
index 0077f68a83..f528e2d081 100644
--- a/xen/arch/x86/hvm/irq.c
+++ b/xen/arch/x86/hvm/irq.c
@@ -385,6 +385,7 @@ void hvm_set_callback_via(struct domain *d, uint64_t via)
     struct hvm_irq *hvm_irq = hvm_domain_irq(d);
     unsigned int gsi=0, pdev=0, pintx=0;
     uint8_t via_type;
+    struct vcpu *v;
 
     via_type = (uint8_t)MASK_EXTR(via, HVM_PARAM_CALLBACK_IRQ_TYPE_MASK) + 1;
     if ( ((via_type == HVMIRQ_callback_gsi) && (via == 0)) ||
@@ -447,6 +448,10 @@ void hvm_set_callback_via(struct domain *d, uint64_t via)
 
     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 )
--
generated by git-patchbot for /home/xen/git/xen.git#stable-4.10

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