accel/kvm: return early from kvm_irqchip_create if kvm does not support irqchip

During refactoring of kvm_irqchip_create(), the refactored code was returning
early from do_kvm_irqchip_create() function if the required essential
capabilities were not present in KVM. This was not translating to an early
return from kvm_irqchip_create() as was the case before refactoring.
This is because, do_kvm_irqchip_create() did not have a means to notify the
caller of the lack of required kvm capabilities. Fix this by making
do_notify_irqchip_create() return EOPNOTSUPP error when  capabilities
are absent and then the caller can check the return code and return early.

Due to this regression during refactoring, all KVM guests on ppc64le hang
immediately during startup and this completely breaks all functionality on
that platform.

Fixes: 98884e0cc1 ("accel/kvm: add changes required to support KVM VM file descriptor change")
Message-ID: <20260413090010.60339-1-anisinha@redhat.com>
Reported-by: Misbah Anjum N <misanjum@linux.ibm.com>
Reported-by: Gautam Menghani <gautam@linux.ibm.com>
Tested-by: Misbah Anjum N <misanjum@linux.ibm.com>
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Ani Sinha <anisinha@redhat.com>
Message-id: 20260414045911.63662-1-anisinha@redhat.com
Suggested-by: Fabiano Rosas <farosas@suse.de>
Suggested-by: Harsh Prateek Bora <harshpb@linux.ibm.com>
Tested-by: Misbah Anjum N <misanjum@linux.ibm.com>
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Ani Sinha <anisinha@redhat.com>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

diff --git a/accel/kvm/kvm-all.c b/accel/kvm/kvm-all.c
index 774499d34f86a652b8fab0e8454ad222bc1d9ea8..92af42503b1cf2c545cbf4c8bdd70b40c93e3cc1 100644 (file)
--- a/accel/kvm/kvm-all.c
+++ b/accel/kvm/kvm-all.c
@@ -2575,7 +2575,7 @@ void kvm_irqchip_set_qemuirq_gsi(KVMState *s, qemu_irq irq, int gsi)
     g_hash_table_insert(s->gsimap, irq, GINT_TO_POINTER(gsi));
 }
 
-static void do_kvm_irqchip_create(KVMState *s)
+static int do_kvm_irqchip_create(KVMState *s)
 {
     int ret;
     if (kvm_check_extension(s, KVM_CAP_IRQCHIP)) {
@@ -2587,7 +2587,7 @@ static void do_kvm_irqchip_create(KVMState *s)
             exit(1);
         }
     } else {
-        return;
+        return -EOPNOTSUPP;
     }
 
     if (kvm_check_extension(s, KVM_CAP_IRQFD) <= 0) {
@@ -2610,13 +2610,17 @@ static void do_kvm_irqchip_create(KVMState *s)
         fprintf(stderr, "Create kernel irqchip failed: %s\n", strerror(-ret));
         exit(1);
     }
+
+    return 0;
 }
 
 static void kvm_irqchip_create(KVMState *s)
 {
     assert(s->kernel_irqchip_split != ON_OFF_AUTO_AUTO);
 
-    do_kvm_irqchip_create(s);
+    if (do_kvm_irqchip_create(s) < 0) {
+        return;
+    }
     kvm_kernel_irqchip = true;
     /* If we have an in-kernel IRQ chip then we must have asynchronous
      * interrupt delivery (though the reverse is not necessarily true)
@@ -2835,6 +2839,7 @@ static int kvm_reset_vmfd(MachineState *ms)
     }
 
     if (s->kernel_irqchip_allowed) {
+        /* ignore return from this function */
         do_kvm_irqchip_create(s);
     }