Anyone to merge this? Thanks, Laurent
Le 20/12/2020 à 17:35, Laurent Vivier a écrit : > 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 <laur...@vivier.eu> > --- > hw/virtio/virtio-mmio.c | 8 ++++++++ > 1 file changed, 8 insertions(+) > > diff --git a/hw/virtio/virtio-mmio.c b/hw/virtio/virtio-mmio.c > index e1b5c3b81e37..610661d6a526 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: >