KVM: Introduce direct MSI message injection for in-kernel irqchips
Currently, MSI messages can only be injected to in-kernel irqchips by
defining a corresponding IRQ route for each message. This is not only
unhandy if the MSI messages are generated "on the fly" by user space,
IRQ routes are a limited resource that user space has to manage
carefully.
By providing a direct injection path, we can both avoid using up limited
resources and simplify the necessary steps for user land.
Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
diff --git a/virt/kvm/Kconfig b/virt/kvm/Kconfig
index f63ccb0..28694f4 100644
--- a/virt/kvm/Kconfig
+++ b/virt/kvm/Kconfig
@@ -18,3 +18,6 @@
config KVM_ASYNC_PF
bool
+
+config HAVE_KVM_MSI
+ bool
diff --git a/virt/kvm/irq_comm.c b/virt/kvm/irq_comm.c
index 9f614b4..a6a0365 100644
--- a/virt/kvm/irq_comm.c
+++ b/virt/kvm/irq_comm.c
@@ -138,6 +138,20 @@
return kvm_irq_delivery_to_apic(kvm, NULL, &irq);
}
+int kvm_send_userspace_msi(struct kvm *kvm, struct kvm_msi *msi)
+{
+ struct kvm_kernel_irq_routing_entry route;
+
+ if (!irqchip_in_kernel(kvm) || msi->flags != 0)
+ return -EINVAL;
+
+ route.msi.address_lo = msi->address_lo;
+ route.msi.address_hi = msi->address_hi;
+ route.msi.data = msi->data;
+
+ return kvm_set_msi(&route, kvm, KVM_USERSPACE_IRQ_SOURCE_ID, 1);
+}
+
/*
* Return value:
* < 0 Interrupt was ignored (masked or not delivered for other reasons)
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 9eb7936..1847c76 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -2060,6 +2060,17 @@
mutex_unlock(&kvm->lock);
break;
#endif
+#ifdef CONFIG_HAVE_KVM_MSI
+ case KVM_SIGNAL_MSI: {
+ struct kvm_msi msi;
+
+ r = -EFAULT;
+ if (copy_from_user(&msi, argp, sizeof msi))
+ goto out;
+ r = kvm_send_userspace_msi(kvm, &msi);
+ break;
+ }
+#endif
default:
r = kvm_arch_vm_ioctl(filp, ioctl, arg);
if (r == -ENOTTY)
@@ -2188,6 +2199,9 @@
case KVM_CAP_SET_BOOT_CPU_ID:
#endif
case KVM_CAP_INTERNAL_ERROR_DATA:
+#ifdef CONFIG_HAVE_KVM_MSI
+ case KVM_CAP_SIGNAL_MSI:
+#endif
return 1;
#ifdef CONFIG_HAVE_KVM_IRQCHIP
case KVM_CAP_IRQ_ROUTING: