On Fri, 2014-09-26 at 17:39 +0200, Antonios Motakis wrote: > On Wed, Sep 24, 2014 at 12:40 AM, Alex Williamson > <alex.williamson@xxxxxxxxxx> wrote: > > On Tue, 2014-09-23 at 16:46 +0200, Antonios Motakis wrote: > >> Some IOMMU drivers, such as the ARM SMMU driver, make available the > >> IOMMU_NOEXEC flag, to set the page tables for a device as XN (execute never). > >> This affects devices such as the ARM PL330 DMA Controller, which respects > >> this flag and will refuse to fetch DMA instructions from memory where the > >> XN flag has been set. > >> > >> The flag can be used only if all IOMMU domains behind the container support > >> the IOMMU_NOEXEC flag. Also, if any mappings are created with the flag, any > >> new domains with devices will have to support it as well. > >> > >> Signed-off-by: Antonios Motakis <a.motakis@xxxxxxxxxxxxxxxxxxxxxx> > >> --- > >> drivers/vfio/vfio_iommu_type1.c | 38 +++++++++++++++++++++++++++++++++++++- > >> 1 file changed, 37 insertions(+), 1 deletion(-) > >> > >> diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c > >> index 0734fbe..09e5064 100644 > >> --- a/drivers/vfio/vfio_iommu_type1.c > >> +++ b/drivers/vfio/vfio_iommu_type1.c > >> @@ -81,6 +81,26 @@ struct vfio_group { > >> }; > >> > >> /* > >> + * This function returns true only if _all_ domains support the capability. > >> + */ > >> +static int vfio_all_domains_have_iommu_noexec(struct vfio_iommu *iommu) > > > > Rename to vfio_domains_have_iommu_noexec() for consistency with the > > cache version. > > > > The logic here is a slightly different logic between the two. For > IOMMU_CACHE we generally check if any domain includes it, Not true, all the domains must support IOMMU_CACHE for the function to return 1. In fact, the code is so identical that if we were to cache IOMMU_CAP_NOEXEC into domain->prot, we should probably only have one function: static int vfio_domains_have_iommu_flag(struct vfio_iommu *iommu, int flag); > for NOEXEC > in contract we need all domains to support it, otherwise we can't > expose the capability. Hence the _all_ addition in the name of the > function. > > >> +{ > >> + struct vfio_domain *d; > >> + int ret = 1; > >> + > >> + mutex_lock(&iommu->lock); > >> + list_for_each_entry(d, &iommu->domain_list, next) { > >> + if (!iommu_domain_has_cap(d->domain, IOMMU_CAP_NOEXEC)) { > > > > Should we cache this in domain->prot like we do for IOMMU_CACHE? > > > >> + ret = 0; > >> + break; > >> + } > >> + } > >> + mutex_unlock(&iommu->lock); > >> + > >> + return ret; > >> +} > >> + > >> +/* > >> * This code handles mapping and unmapping of user data buffers > >> * into DMA'ble space using the IOMMU > >> */ > >> @@ -546,6 +566,11 @@ static int vfio_dma_do_map(struct vfio_iommu *iommu, > >> prot |= IOMMU_WRITE; > >> if (map->flags & VFIO_DMA_MAP_FLAG_READ) > >> prot |= IOMMU_READ; > >> + if (map->flags & VFIO_DMA_MAP_FLAG_NOEXEC) { > >> + if (!vfio_all_domains_have_iommu_noexec(iommu)) > >> + return -EINVAL; > >> + prot |= IOMMU_NOEXEC; > >> + } > >> > >> if (!prot || !size || (size | iova | vaddr) & mask) > >> return -EINVAL; > >> @@ -636,6 +661,12 @@ static int vfio_iommu_replay(struct vfio_iommu *iommu, > >> dma = rb_entry(n, struct vfio_dma, node); > >> iova = dma->iova; > >> > >> + /* if any of the mappings to be replayed has the NOEXEC flag > >> + * set, then the new iommu domain must support it */ > > > > nit, please fix the comment style to match the rest of the file. > > > > Ack > > >> + if ((dma->prot | IOMMU_NOEXEC) && > >> + !iommu_domain_has_cap(domain->domain, IOMMU_CAP_NOEXEC)) > >> + return -EINVAL; > >> + > >> while (iova < dma->iova + dma->size) { > >> phys_addr_t phys = iommu_iova_to_phys(d->domain, iova); > >> size_t size; > >> @@ -890,6 +921,10 @@ static long vfio_iommu_type1_ioctl(void *iommu_data, > >> if (!iommu) > >> return 0; > >> return vfio_domains_have_iommu_cache(iommu); > >> + case VFIO_IOMMU_PROT_NOEXEC: > >> + if (!iommu) > >> + return 0; > >> + return vfio_all_domains_have_iommu_noexec(iommu); > >> default: > >> return 0; > >> } > >> @@ -913,7 +948,8 @@ static long vfio_iommu_type1_ioctl(void *iommu_data, > >> } else if (cmd == VFIO_IOMMU_MAP_DMA) { > >> struct vfio_iommu_type1_dma_map map; > >> uint32_t mask = VFIO_DMA_MAP_FLAG_READ | > >> - VFIO_DMA_MAP_FLAG_WRITE; > >> + VFIO_DMA_MAP_FLAG_WRITE | > >> + VFIO_DMA_MAP_FLAG_NOEXEC; > >> > >> minsz = offsetofend(struct vfio_iommu_type1_dma_map, size); > >> > > > > > > > > > -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html