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@xxxxxxx>
---
Changelog v2 .. v3:
- return Linux errors to userland
Changelog v1 .. v2:
- properly detect unmapped LPIs and report this to userland
include/linux/irqchip/arm-gic-v3.h | 1 +
virt/kvm/arm/vgic/vgic-its.c | 56 +++++++++++++++++++++++++-------------
2 files changed, 38 insertions(+), 19 deletions(-)
diff --git a/include/linux/irqchip/arm-gic-v3.h b/include/linux/irqchip/arm-gic-v3.h
index 56b0b7e..99ac022 100644
--- 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 7180994..3c029cd 100644
--- 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);
}
/*
--
2.9.0
--
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