From b6bff10a7af29ddbf863f1bc7956acc8b156f7d5 Mon Sep 17 00:00:00 2001
From: xiangzixuan <xiangzixuan@huawei.com>
Date: Thu, 18 Dec 2025 15:53:52 +0800
Subject: [PATCH] ub: check kvm_usi_via_irqfd when set kvm interrupt

check if kvm_usi_via_irqfd enabled before set kvm interrupt

Signed-off-by: xiangzixuan <xiangzixuan@huawei.com>
---
 accel/kvm/kvm-all.c  |  2 ++
 hw/ub/ub_ummu.c      |  5 +++++
 hw/vfio/ub.c         |  7 ++++++-
 include/sysemu/kvm.h | 11 +++++++++++
 4 files changed, 24 insertions(+), 1 deletion(-)

diff --git a/accel/kvm/kvm-all.c b/accel/kvm/kvm-all.c
index 386d5b3a53d..3107ca1a647 100644
--- a/accel/kvm/kvm-all.c
+++ b/accel/kvm/kvm-all.c
@@ -112,6 +112,7 @@ bool kvm_readonly_mem_allowed;
 bool kvm_vm_attributes_allowed;
 bool kvm_msi_use_devid;
 bool kvm_csv3_allowed;
+bool kvm_usi_via_irqfd_allowed;
 static bool kvm_has_guest_debug;
 static int kvm_sstep_flags;
 static bool kvm_immediate_exit;
@@ -2421,6 +2422,7 @@ static void kvm_irqchip_create(KVMState *s)
      */
     kvm_async_interrupts_allowed = true;
     kvm_halt_in_kernel_allowed = true;
+    kvm_usi_via_irqfd_allowed = true;
 
     kvm_init_irq_routing(s);
 
diff --git a/hw/ub/ub_ummu.c b/hw/ub/ub_ummu.c
index 5eff0c1f6ed..24999cf559b 100644
--- a/hw/ub/ub_ummu.c
+++ b/hw/ub/ub_ummu.c
@@ -919,6 +919,11 @@ static void ummu_glb_int_enable(UMMUState *u, UMMUUSIVectorType type)
     USIMessage msg;
     uint32_t interrupt_id = UMMU_INTERRUPT_ID;
 
+    if (!kvm_usi_via_irqfd_enabled()) {
+        qemu_log("kvm usi via irqfd disabled.\n");
+        return;
+    }
+
     if (type == UMMU_USI_VECTOR_EVETQ) {
         msg = ummu_get_eventq_usi_message(u);
     } else {
diff --git a/hw/vfio/ub.c b/hw/vfio/ub.c
index 1f0d511bc0d..568000858aa 100644
--- a/hw/vfio/ub.c
+++ b/hw/vfio/ub.c
@@ -521,6 +521,11 @@ static int vfio_usi_vector_do_use(UBDevice *udev, uint16_t nr, USIMessage *msg,
     int ret;
     Error *err = NULL;
 
+    if (!kvm_usi_via_irqfd_enabled()) {
+        qemu_log("kvm usi via irqfd disabled.\n");
+        return 0;
+    }
+
     vector = &vdev->usi_vectors[nr];
     if (!vector->use) {
         vfio_vector_init(vdev, nr);
@@ -1283,4 +1288,4 @@ static void register_vfio_ub_dev_types(void)
     type_register_static(&vfio_ub_dev_info);
 }
 
-type_init(register_vfio_ub_dev_types)
\ No newline at end of file
+type_init(register_vfio_ub_dev_types)
diff --git a/include/sysemu/kvm.h b/include/sysemu/kvm.h
index 4669c070d63..5f0a48891ab 100644
--- a/include/sysemu/kvm.h
+++ b/include/sysemu/kvm.h
@@ -40,6 +40,7 @@ extern bool kvm_async_interrupts_allowed;
 extern bool kvm_halt_in_kernel_allowed;
 extern bool kvm_resamplefds_allowed;
 extern bool kvm_msi_via_irqfd_allowed;
+extern bool kvm_usi_via_irqfd_allowed;
 extern bool kvm_gsi_routing_allowed;
 extern bool kvm_gsi_direct_mapping;
 extern bool kvm_readonly_mem_allowed;
@@ -109,6 +110,15 @@ extern bool kvm_csv3_allowed;
  */
 #define kvm_resamplefds_enabled() (kvm_resamplefds_allowed)
 
+/**
+ * kvm_usi_via_irqfd_enabled:
+ *
+ * Returns: true if we can route a USI (UB Signaled Interrupt)
+ * to a KVM CPU via an irqfd. This requires that the kernel supports
+ * this and that we're running in a configuration that permits it.
+ */
+#define kvm_usi_via_irqfd_enabled() (kvm_usi_via_irqfd_allowed)
+
 /**
  * kvm_msi_via_irqfd_enabled:
  *
@@ -174,6 +184,7 @@ extern bool kvm_csv3_allowed;
 #define kvm_irqfds_enabled() (false)
 #define kvm_resamplefds_enabled() (false)
 #define kvm_msi_via_irqfd_enabled() (false)
+#define kvm_usi_via_irqfd_enabled() (false)
 #define kvm_gsi_routing_allowed() (false)
 #define kvm_gsi_direct_mapping() (false)
 #define kvm_readonly_mem_enabled() (false)
-- 
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