Michael S. Tsirkin
2021-Dec-07 08:13 UTC
[RFC PATCH] virtio: make sure legacy pci device gain 32bit-pfn vq
On Tue, Dec 07, 2021 at 03:51:45PM +0800, ?? wrote:> We observed issues like: > virtio-pci 0000:14:00.0: platform bug: legacy virtio-mmio must > not be used with RAM above 0x4000GB > > when we have a legacy pci device which desired 32bit-pfn vq > but gain 64bit-pfn instead, lead into the failure of probe. > > vring_use_dma_api() is playing the key role in here, to help the > allocation process understand which kind of vq it should alloc, > however, it failed to take care the legacy pci device, which only > have 32bit feature flag and can never have VIRTIO_F_ACCESS_PLATFORM > setted. > > This patch introduce force_dma flag to help vring_use_dma_api() > understanding the requirement better, to avoid the failing. > > Signed-off-by: Michael Wang <yun.wang at linux.alibaba.com>This will break configs where the device appears behind a virtual iommu, so this won't fly. Just make your device support 1.0, eh?> --- > drivers/virtio/virtio_pci_legacy.c | 10 ++++++++++ > drivers/virtio/virtio_ring.c | 3 +++ > include/linux/virtio.h | 1 + > 3 files changed, 14 insertions(+) > > diff --git a/drivers/virtio/virtio_pci_legacy.c > b/drivers/virtio/virtio_pci_legacy.c > index d62e983..11f2ebf 100644 > --- a/drivers/virtio/virtio_pci_legacy.c > +++ b/drivers/virtio/virtio_pci_legacy.c > @@ -263,6 +263,16 @@ int virtio_pci_legacy_probe(struct virtio_pci_device > *vp_dev) > vp_dev->setup_vq = setup_vq; > vp_dev->del_vq = del_vq; > > + /* > + * The legacy pci device requre 32bit-pfn vq, > + * or setup_vq() will failed. > + * > + * Thus we make sure vring_use_dma_api() will > + * return true during the allocation by marking > + * force_dma here. > + */ > + vp_dev->vdev.force_dma = true; > + > return 0; > > err_iomap: > diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c > index 3035bb6..6562e01 100644 > --- a/drivers/virtio/virtio_ring.c > +++ b/drivers/virtio/virtio_ring.c > @@ -245,6 +245,9 @@ static inline bool virtqueue_use_indirect(struct > virtqueue *_vq, > > static bool vring_use_dma_api(struct virtio_device *vdev) > { > + if (vdev->force_dma) > + return true; > + > if (!virtio_has_dma_quirk(vdev)) > return true; > > diff --git a/include/linux/virtio.h b/include/linux/virtio.h > index 41edbc0..a4eb29d 100644 > --- a/include/linux/virtio.h > +++ b/include/linux/virtio.h > @@ -109,6 +109,7 @@ struct virtio_device { > bool failed; > bool config_enabled; > bool config_change_pending; > + bool force_dma; > spinlock_t config_lock; > spinlock_t vqs_list_lock; /* Protects VQs list access */ > struct device dev; > -- > 1.8.3.1