diff options
| author | Laurent Vivier <laurent@vivier.eu> | 2020-12-20 17:35:39 +0100 |
|---|---|---|
| committer | Michael S. Tsirkin <mst@redhat.com> | 2021-02-05 08:52:58 -0500 |
| commit | 2d9e7d4cddd901a3cb57d2fc150186c70b7139a7 (patch) | |
| tree | 1f132158659da1345265525b3e92b94d2c9e3619 | |
| parent | c126b4c57e0164549de606ca35d1512762051083 (diff) | |
virtio-mmio: fix guest kernel crash with SHM regions
In the kernel, virtio_gpu_init() uses virtio_get_shm_region()
since
commit 6076a9711dc5 ("drm/virtio: implement blob resources: probe for host visible region")
but vm_get_shm_region() unconditionally uses VIRTIO_MMIO_SHM_SEL to
get the address and the length of the region.
commit 38e895487afc ("virtio: Implement get_shm_region for MMIO transport"
As this is not implemented in QEMU, address and length are 0 and passed
as is to devm_request_mem_region() that triggers a crash:
[drm:virtio_gpu_init] *ERROR* Could not reserve host visible region
Unable to handle kernel NULL pointer dereference at virtual address (ptrval)
According to the comments in the kernel, a non existent shared region
has a length of (u64)-1.
This is what we return now with this patch to disable the region.
Signed-off-by: Laurent Vivier <laurent@vivier.eu>
Message-Id: <20201220163539.2255963-1-laurent@vivier.eu>
Acked-by: Gerd Hoffmann <kraxel@redhat.com>
Reviewed-by: Stefano Garzarella <sgarzare@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
| -rw-r--r-- | hw/virtio/virtio-mmio.c | 8 |
1 files changed, 8 insertions, 0 deletions
diff --git a/hw/virtio/virtio-mmio.c b/hw/virtio/virtio-mmio.c index e1b5c3b81e..610661d6a5 100644 --- a/hw/virtio/virtio-mmio.c +++ b/hw/virtio/virtio-mmio.c @@ -191,6 +191,14 @@ static uint64_t virtio_mmio_read(void *opaque, hwaddr offset, unsigned size) return 0; } return vdev->generation; + case VIRTIO_MMIO_SHM_LEN_LOW: + case VIRTIO_MMIO_SHM_LEN_HIGH: + /* + * VIRTIO_MMIO_SHM_SEL is unimplemented + * according to the linux driver, if region length is -1 + * the shared memory doesn't exist + */ + return -1; case VIRTIO_MMIO_DEVICE_FEATURES_SEL: case VIRTIO_MMIO_DRIVER_FEATURES: case VIRTIO_MMIO_DRIVER_FEATURES_SEL: |