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.
> +{
> + 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.
> + 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);
>
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