KVM: arm64: ITS: return 1 on successful MSI injection

According to the KVM API documentation a successful MSI injection
should return a value > 0 on success.
Return possible errors in vgic_its_trigger_msi() and report a
successful injection back to userland, while also reporting the
case where the MSI could not be delivered due to the guest not
having the LPI mapped, for instance.

Signed-off-by: Andre Przywara <andre.przywara@arm.com>
Reviewed-by: Eric Auger <eric.auger@redhat.com>
Reviewed-by: Christoffer Dall <christoffer.dall@linaro.org>
Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org>

diff --git a/include/linux/irqchip/arm-gic-v3.h b/include/linux/irqchip/arm-gic-v3.h
index 56b0b7ec66aacd6bb895deb21d818ef9b068e801..99ac022edc60633be531e5df89d252d26f1b0766 100644 (file)
--- a/include/linux/irqchip/arm-gic-v3.h
+++ b/include/linux/irqchip/arm-gic-v3.h
@@ -337,6 +337,7 @@
  */
 #define E_ITS_MOVI_UNMAPPED_INTERRUPT          0x010107
 #define E_ITS_MOVI_UNMAPPED_COLLECTION         0x010109
+#define E_ITS_INT_UNMAPPED_INTERRUPT           0x010307
 #define E_ITS_CLEAR_UNMAPPED_INTERRUPT         0x010507
 #define E_ITS_MAPD_DEVICE_OOR                  0x010801
 #define E_ITS_MAPC_PROCNUM_OOR                 0x010902

diff --git a/virt/kvm/arm/vgic/vgic-its.c b/virt/kvm/arm/vgic/vgic-its.c
index 07411cf967b98767bada3c6287fc1cc69c53a86a..1bd8adbeae260cc36c23f7750c6d842aa0f8b5a0 100644 (file)
--- a/virt/kvm/arm/vgic/vgic-its.c
+++ b/virt/kvm/arm/vgic/vgic-its.c
@@ -441,39 +441,48 @@ static unsigned long vgic_mmio_read_its_idregs(struct kvm *kvm,
  * Find the target VCPU and the LPI number for a given devid/eventid pair
  * and make this IRQ pending, possibly injecting it.
  * Must be called with the its_lock mutex held.
+ * Returns 0 on success, a positive error value for any ITS mapping
+ * related errors and negative error values for generic errors.
  */
-static void vgic_its_trigger_msi(struct kvm *kvm, struct vgic_its *its,
-                                u32 devid, u32 eventid)
+static int vgic_its_trigger_msi(struct kvm *kvm, struct vgic_its *its,
+                               u32 devid, u32 eventid)
 {
+       struct kvm_vcpu *vcpu;
        struct its_itte *itte;
 
        if (!its->enabled)
-               return;
+               return -EBUSY;
 
        itte = find_itte(its, devid, eventid);
-       /* Triggering an unmapped IRQ gets silently dropped. */
-       if (itte && its_is_collection_mapped(itte->collection)) {
-               struct kvm_vcpu *vcpu;
-
-               vcpu = kvm_get_vcpu(kvm, itte->collection->target_addr);
-               if (vcpu && vcpu->arch.vgic_cpu.lpis_enabled) {
-                       spin_lock(&itte->irq->irq_lock);
-                       itte->irq->pending = true;
-                       vgic_queue_irq_unlock(kvm, itte->irq);
-               }
-       }
+       if (!itte || !its_is_collection_mapped(itte->collection))
+               return E_ITS_INT_UNMAPPED_INTERRUPT;
+
+       vcpu = kvm_get_vcpu(kvm, itte->collection->target_addr);
+       if (!vcpu)
+               return E_ITS_INT_UNMAPPED_INTERRUPT;
+
+       if (!vcpu->arch.vgic_cpu.lpis_enabled)
+               return -EBUSY;
+
+       spin_lock(&itte->irq->irq_lock);
+       itte->irq->pending = true;
+       vgic_queue_irq_unlock(kvm, itte->irq);
+
+       return 0;
 }
 
 /*
  * Queries the KVM IO bus framework to get the ITS pointer from the given
  * doorbell address.
  * We then call vgic_its_trigger_msi() with the decoded data.
+ * According to the KVM_SIGNAL_MSI API description returns 1 on success.
  */
 int vgic_its_inject_msi(struct kvm *kvm, struct kvm_msi *msi)
 {
        u64 address;
        struct kvm_io_device *kvm_io_dev;
        struct vgic_io_device *iodev;
+       int ret;
 
        if (!vgic_has_its(kvm))
                return -ENODEV;
@@ -490,10 +499,21 @@ int vgic_its_inject_msi(struct kvm *kvm, struct kvm_msi *msi)
        iodev = container_of(kvm_io_dev, struct vgic_io_device, dev);
 
        mutex_lock(&iodev->its->its_lock);
-       vgic_its_trigger_msi(kvm, iodev->its, msi->devid, msi->data);
+       ret = vgic_its_trigger_msi(kvm, iodev->its, msi->devid, msi->data);
        mutex_unlock(&iodev->its->its_lock);
 
-       return 0;
+       if (ret < 0)
+               return ret;
+
+       /*
+        * KVM_SIGNAL_MSI demands a return value > 0 for success and 0
+        * if the guest has blocked the MSI. So we map any LPI mapping
+        * related error to that.
+        */
+       if (ret)
+               return 0;
+       else
+               return 1;
 }
 
 /* Requires the its_lock to be held. */
@@ -981,9 +1001,7 @@ static int vgic_its_cmd_handle_int(struct kvm *kvm, struct vgic_its *its,
        u32 msi_data = its_cmd_get_id(its_cmd);
        u64 msi_devid = its_cmd_get_deviceid(its_cmd);
 
-       vgic_its_trigger_msi(kvm, its, msi_devid, msi_data);
-
-       return 0;
+       return vgic_its_trigger_msi(kvm, its, msi_devid, msi_data);
 }
 
 /*