Messages in this thread | | | Subject | Re: [PATCH 3/4] vdpa: get_iova_range() is mandatory for device specific DMA translation | From | Jason Wang <> | Date | Thu, 6 Aug 2020 11:27:16 +0800 |
| |
On 2020/8/5 下午8:55, Michael S. Tsirkin wrote: > On Wed, Jun 17, 2020 at 11:29:46AM +0800, Jason Wang wrote: >> In order to let userspace work correctly, get_iova_range() is a must >> for the device that has its own DMA translation logic. > I guess you mean for a device. > > However in absence of ths op, I don't see what is wrong with just > assuming device can access any address.
It's just for safe, if you want, we can assume any address without this op.
> >> Signed-off-by: Jason Wang <jasowang@redhat.com> >> --- >> drivers/vdpa/vdpa.c | 4 ++++ >> 1 file changed, 4 insertions(+) >> >> diff --git a/drivers/vdpa/vdpa.c b/drivers/vdpa/vdpa.c >> index de211ef3738c..ab7af978ef70 100644 >> --- a/drivers/vdpa/vdpa.c >> +++ b/drivers/vdpa/vdpa.c >> @@ -82,6 +82,10 @@ struct vdpa_device *__vdpa_alloc_device(struct device *parent, >> if (!!config->dma_map != !!config->dma_unmap) >> goto err; >> >> + if ((config->dma_map || config->set_map) && >> + !config->get_iova_range) >> + goto err; >> + >> err = -ENOMEM; >> vdev = kzalloc(size, GFP_KERNEL); >> if (!vdev) > What about devices using an IOMMU for translation? > IOMMUs generally have a limited IOVA range too, right?
See patch 4 which query the IOMMU geometry in this case:
+ iommu_domain_get_attr(v->domain, + DOMAIN_ATTR_GEOMETRY, &geo); + range.start = geo.aperture_start; + range.end = geo.aperture_end;
Thanks
> > > >> -- >> 2.20.1
| |