On Fri, Sep 26, 2014 at 10:27 PM, Alex Williamson <alex.williamson@xxxxxxxxxx> wrote: > 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); > You are absolutely correct, I managed to confuse myself when switching from vfio_domains_have_iommu_exec to vfio_domains_have_iommu_noexec. I will implement the shared function. >> 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); >> >> >> > >> > >> > >> >> >> > > > -- Antonios Motakis Virtual Open Systems -- 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