At the moment the IRQ line for a virtio-mmio device is assigned in the
generic device__register() routine in devices.c, by calling back into
virtio-mmio.c. This does not only sound slightly convoluted, but also
breaks when we try to register an MMIO device that is not a virtio-mmio
device. In this case container_of will return a bogus pointer (as it
assumes a struct virtio_mmio), and the IRQ allocation routine will
corrupt some data in the device_header (for instance the first byte
of the "data" pointer).

Simply assign the IRQ directly in virtio_mmio_init(), before calling
device__register(). This avoids the problem and looks actually much more
straightforward.

Signed-off-by: Andre Przywara <[email protected]>
---
 devices.c                 |  4 ----
 include/kvm/virtio-mmio.h |  1 -
 virtio/mmio.c             | 10 ++--------
 3 files changed, 2 insertions(+), 13 deletions(-)

diff --git a/devices.c b/devices.c
index a7c666a7..2c8b2665 100644
--- a/devices.c
+++ b/devices.c
@@ -1,7 +1,6 @@
 #include "kvm/devices.h"
 #include "kvm/kvm.h"
 #include "kvm/pci.h"
-#include "kvm/virtio-mmio.h"
 
 #include <linux/err.h>
 #include <linux/rbtree.h>
@@ -33,9 +32,6 @@ int device__register(struct device_header *dev)
        case DEVICE_BUS_PCI:
                pci__assign_irq(dev);
                break;
-       case DEVICE_BUS_MMIO:
-               virtio_mmio_assign_irq(dev);
-               break;
        default:
                break;
        }
diff --git a/include/kvm/virtio-mmio.h b/include/kvm/virtio-mmio.h
index 0528947a..6bc50bd1 100644
--- a/include/kvm/virtio-mmio.h
+++ b/include/kvm/virtio-mmio.h
@@ -57,5 +57,4 @@ int virtio_mmio_exit(struct kvm *kvm, struct virtio_device 
*vdev);
 int virtio_mmio_reset(struct kvm *kvm, struct virtio_device *vdev);
 int virtio_mmio_init(struct kvm *kvm, void *dev, struct virtio_device *vdev,
                      int device_id, int subsys_id, int class);
-void virtio_mmio_assign_irq(struct device_header *dev_hdr);
 #endif
diff --git a/virtio/mmio.c b/virtio/mmio.c
index 5537c393..875a288c 100644
--- a/virtio/mmio.c
+++ b/virtio/mmio.c
@@ -280,14 +280,6 @@ static void generate_virtio_mmio_fdt_node(void *fdt,
 }
 #endif
 
-void virtio_mmio_assign_irq(struct device_header *dev_hdr)
-{
-       struct virtio_mmio *vmmio = container_of(dev_hdr,
-                                                struct virtio_mmio,
-                                                dev_hdr);
-       vmmio->irq = irq__alloc_line();
-}
-
 int virtio_mmio_init(struct kvm *kvm, void *dev, struct virtio_device *vdev,
                     int device_id, int subsys_id, int class)
 {
@@ -316,6 +308,8 @@ int virtio_mmio_init(struct kvm *kvm, void *dev, struct 
virtio_device *vdev,
                .data           = generate_virtio_mmio_fdt_node,
        };
 
+       vmmio->irq = irq__alloc_line();
+
        r = device__register(&vmmio->dev_hdr);
        if (r < 0) {
                kvm__deregister_mmio(kvm, vmmio->addr);
-- 
2.17.1

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