Re: [PATCH v3 13/13] KVM: selftests: Add a KVM_IRQFD test to verify uniqueness requirements

[Sairaj Kodilkar]

On 5/23/2025 5:22 AM, Sean Christopherson wrote:

+
+int main(int argc, char *argv[])
+{
+       pthread_t racing_thread;
+       int r, i;
+
+       /* Create "full" VMs, as KVM_IRQFD requires an in-kernel IRQ chip. */
+       vm1 = vm_create(1);
+       vm2 = vm_create(1);
+
+       WRITE_ONCE(__eventfd, kvm_new_eventfd());
+
+       kvm_irqfd(vm1, 10, __eventfd, 0);
+
+       r = __kvm_irqfd(vm1, 11, __eventfd, 0);
+       TEST_ASSERT(r && errno == EBUSY,
+                   "Wanted EBUSY, r = %d, errno = %d", r, errno);
+
+       r = __kvm_irqfd(vm2, 12, __eventfd, 0);
+       TEST_ASSERT(r && errno == EBUSY,
+                   "Wanted EBUSY, r = %d, errno = %d", r, errno);
+
+       kvm_irqfd(vm1, 11, READ_ONCE(__eventfd), KVM_IRQFD_FLAG_DEASSIGN);
+       kvm_irqfd(vm1, 12, READ_ONCE(__eventfd), KVM_IRQFD_FLAG_DEASSIGN);
+       kvm_irqfd(vm1, 13, READ_ONCE(__eventfd), KVM_IRQFD_FLAG_DEASSIGN);
+       kvm_irqfd(vm1, 14, READ_ONCE(__eventfd), KVM_IRQFD_FLAG_DEASSIGN);

Hi Sean,
I dont see any allocation for the GSI 13 and 14..
Is there any reason for the deassigning these two GSIs ?

Regards
Sairaj Kodilkar

+       kvm_irqfd(vm1, 10, READ_ONCE(__eventfd), KVM_IRQFD_FLAG_DEASSIGN);
+
+       close(__eventfd);
+
+       pthread_create(&racing_thread, NULL, secondary_irqfd_juggler, vm2);
+
+       for (i = 0; i < 10000; i++) {
+               WRITE_ONCE(__eventfd, kvm_new_eventfd());
+
+               juggle_eventfd_primary(vm1, __eventfd);
+               juggle_eventfd_primary(vm2, __eventfd);
+               close(__eventfd);
+       }
+
+       WRITE_ONCE(done, true);
+       pthread_join(racing_thread, NULL);
+}