[RFC PATCH 18/21] kvm/ioapic: mark gsi-2 used in ioapic routing init

[David Woodhouse]

From: Ankur Arora <ankur.a.arora@oracle.com>

GSI-2/IOAPIC pin-2 is treated specially while initing
IRQ routing: PIC does not use it at all while the IOAPIC
maps virq=0 to pin-2 and does not use GSI-2.
(all other GSIs are identity mapped to pins.)

This results in any later code which allocates a virq
to be assigned GSI-2. This virq is in-turn used to
remap interrupts to HYPERVISOR_CALLBACK_VECTOR (0xf3)
to deliver to the guest.

Ordinarily this would be okay, but if the event delivery is
via direct injection via KVM_REQ_EVENT (without going
through the LAPIC) we see vmentry failure.

This works fine for any other values of GSI.

As a workaround, mark GSI-2 used.

Signed-off-by: Ankur Arora <ankur.a.arora@oracle.com>
Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
---
 accel/kvm/kvm-all.c  | 5 +++++
 hw/i386/kvm/ioapic.c | 1 +
 include/sysemu/kvm.h | 1 +
 3 files changed, 7 insertions(+)

diff --git a/accel/kvm/kvm-all.c b/accel/kvm/kvm-all.c
index 8a227515b7..b40cfc4144 100644
--- a/accel/kvm/kvm-all.c
+++ b/accel/kvm/kvm-all.c
@@ -1677,6 +1677,11 @@ static void set_gsi(KVMState *s, unsigned int gsi)
     set_bit(gsi, s->used_gsi_bitmap);
 }
 
+void kvm_irqchip_set_gsi(KVMState *s, unsigned int gsi)
+{
+    set_gsi(s, gsi);
+}
+
 static void clear_gsi(KVMState *s, unsigned int gsi)
 {
     clear_bit(gsi, s->used_gsi_bitmap);
diff --git a/hw/i386/kvm/ioapic.c b/hw/i386/kvm/ioapic.c
index ee7c8ef68b..5fab0d35c9 100644
--- a/hw/i386/kvm/ioapic.c
+++ b/hw/i386/kvm/ioapic.c
@@ -43,6 +43,7 @@ void kvm_pc_setup_irq_routing(bool pci_enabled)
             }
         }
     }
+    kvm_irqchip_set_gsi(s, 2);
     kvm_irqchip_commit_routes(s);
 }
 
diff --git a/include/sysemu/kvm.h b/include/sysemu/kvm.h
index 8e882fbe96..a249ea480f 100644
--- a/include/sysemu/kvm.h
+++ b/include/sysemu/kvm.h
@@ -512,6 +512,7 @@ static inline void 
kvm_irqchip_commit_route_changes(KVMRouteChange *c)
 }
 
 void kvm_irqchip_release_virq(KVMState *s, int virq);
+void kvm_irqchip_set_gsi(KVMState *s, unsigned int gsi);
 
 int kvm_irqchip_add_adapter_route(KVMState *s, AdapterInfo *adapter);
 int kvm_irqchip_add_hv_sint_route(KVMState *s, uint32_t vcpu, uint32_t sint);
-- 
2.35.3