Hi Jean, > -----Original Message----- > From: Auger Eric <[email protected]> > Sent: Thursday, March 26, 2020 11:11 PM > To: Jean-Philippe Brucker <[email protected]>; [email protected] > foundation.org > Cc: [email protected]; [email protected]; > [email protected]; > [email protected]; Bharat Bhushan <[email protected]> > Subject: [EXT] Re: [PATCH v2 3/3] iommu/virtio: Reject IOMMU page granule > larger > than PAGE_SIZE > > External Email > > ---------------------------------------------------------------------- > Hi Jean, > > On 3/26/20 10:35 AM, Jean-Philippe Brucker wrote: > > We don't currently support IOMMUs with a page granule larger than the > > system page size. The IOVA allocator has a BUG_ON() in this case, and > > VFIO has a WARN_ON(). > > > > Removing these obstacles ranges doesn't seem possible without major > > changes to the DMA API and VFIO. Some callers of iommu_map(), for > > example, want to map multiple page-aligned regions adjacent to each > > others for scatter-gather purposes. Even in simple DMA API uses, a > > call to dma_map_page() would let the endpoint access neighbouring > > memory. And VFIO users cannot ensure that their virtual address buffer > > is physically contiguous at the IOMMU granule. > > > > Rather than triggering the IOVA BUG_ON() on mismatched page sizes, > > abort the vdomain finalise() with an error message. We could simply > > abort the viommu probe(), but an upcoming extension to virtio-iommu > > will allow setting different page masks for each endpoint. > > > > Reported-by: Bharat Bhushan <[email protected]> > > Signed-off-by: Jean-Philippe Brucker <[email protected]> > Reviewed-by: Eric Auger <[email protected]>
Reviewed-by: Eric Auger <[email protected]> Thanks -Bharat > > Thanks > > Eric > > --- > > v1->v2: Move to vdomain_finalise(), improve commit message > > --- > > drivers/iommu/virtio-iommu.c | 14 ++++++++++++-- > > 1 file changed, 12 insertions(+), 2 deletions(-) > > > > diff --git a/drivers/iommu/virtio-iommu.c > > b/drivers/iommu/virtio-iommu.c index 5eed75cd121f..750f69c49b95 100644 > > --- a/drivers/iommu/virtio-iommu.c > > +++ b/drivers/iommu/virtio-iommu.c > > @@ -607,12 +607,22 @@ static struct iommu_domain > *viommu_domain_alloc(unsigned type) > > return &vdomain->domain; > > } > > > > -static int viommu_domain_finalise(struct viommu_dev *viommu, > > +static int viommu_domain_finalise(struct viommu_endpoint *vdev, > > struct iommu_domain *domain) > > { > > int ret; > > + unsigned long viommu_page_size; > > + struct viommu_dev *viommu = vdev->viommu; > > struct viommu_domain *vdomain = to_viommu_domain(domain); > > > > + viommu_page_size = 1UL << __ffs(viommu->pgsize_bitmap); > > + if (viommu_page_size > PAGE_SIZE) { > > + dev_err(vdev->dev, > > + "granule 0x%lx larger than system page size 0x%lx\n", > > + viommu_page_size, PAGE_SIZE); > > + return -EINVAL; > > + } > > + > > ret = ida_alloc_range(&viommu->domain_ids, viommu->first_domain, > > viommu->last_domain, GFP_KERNEL); > > if (ret < 0) > > @@ -659,7 +669,7 @@ static int viommu_attach_dev(struct iommu_domain > *domain, struct device *dev) > > * Properly initialize the domain now that we know which viommu > > * owns it. > > */ > > - ret = viommu_domain_finalise(vdev->viommu, domain); > > + ret = viommu_domain_finalise(vdev, domain); > > } else if (vdomain->viommu != vdev->viommu) { > > dev_err(dev, "cannot attach to foreign vIOMMU\n"); > > ret = -EXDEV; > > _______________________________________________ iommu mailing list [email protected] https://lists.linuxfoundation.org/mailman/listinfo/iommu
