On 2023-05-16 01:00, Jason Gunthorpe wrote:
Even though dma-iommu.c and CONFIG_ARM_DMA_USE_IOMMU do approximately the same stuff, the way they relate to the IOMMU core is quiet different.dma-iommu.c expects the core code to setup an UNMANAGED domain (of type IOMMU_DOMAIN_DMA) and then configures itself to use that domain. This becomes the default_domain for the group. ARM_DMA_USE_IOMMU does not use the default_domain, instead it directly allocates an UNMANAGED domain and operates it just like an external driver. In this case group->default_domain is NULL. If the driver provides a global static identity_domain then automatically use it as the default_domain when in ARM_DMA_USE_IOMMU mode. This allows drivers that implemented default_domain == NULL as an IDENTITY translation to trivially get a properly labeled non-NULL default_domain on ARM32 configs. With this arrangment when ARM_DMA_USE_IOMMU wants to disconnect from the device the normal detach_domain flow will restore the IDENTITY domain as the default domain. Overall this makes attach_dev() of the IDENTITY domain called in the same places as detach_dev(). This effectively migrates these drivers to default_domain mode. For drivers that support ARM64 they will gain support for the IDENTITY translation mode for the dma_api and behave in a uniform way. Drivers use this by setting ops->identity_domain to a static singleton iommu_domain that implements the identity attach. If the core detects ARM_DMA_USE_IOMMU mode then it automatically attaches the IDENTITY domain during probe. Drivers can continue to prevent the use of DMA translation by returning IOMMU_DOMAIN_IDENTITY from def_domain_type, this will completely prevent IOMMU_DMA from running but will not impact ARM_DMA_USE_IOMMU. This allows removing the set_platform_dma_ops() from every remaining driver. Remove the set_platform_dma_ops from rockchip and mkt_v1 as all it does is set an existing global static identity domain. mkt_v1 does not support IOMMU_DOMAIN_DMA and it does not compile on ARM64 so this transformation is safe. Signed-off-by: Jason Gunthorpe <j...@nvidia.com> --- drivers/iommu/iommu.c | 40 +++++++++++++++++++++++++++++----- drivers/iommu/mtk_iommu_v1.c | 12 ---------- drivers/iommu/rockchip-iommu.c | 10 --------- 3 files changed, 35 insertions(+), 27 deletions(-) diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c index 8ba90571449cec..bed7cb6e5ee65b 100644 --- a/drivers/iommu/iommu.c +++ b/drivers/iommu/iommu.c @@ -1757,18 +1757,48 @@ static int iommu_get_default_domain_type(struct iommu_group *group, int type;lockdep_assert_held(&group->mutex);+ + /* + * ARM32 drivers supporting CONFIG_ARM_DMA_USE_IOMMU can declare an + * identity_domain and it will automatically become their default + * domain. Later on ARM_DMA_USE_IOMMU will install its UNMANAGED domain. + * Override the selection to IDENTITY if we are sure the driver supports + * it. + */ + if (IS_ENABLED(CONFIG_ARM_DMA_USE_IOMMU) && ops->identity_domain) {
If I cared about arm-smmu on 32-bit, I'd bring that up again, but honestly I'm not sure that I do... I think it might end up working after patch #21, and it's currently still broken for lack of .set_platform_dma anyway, so meh.
+ type = IOMMU_DOMAIN_IDENTITY; + if (best_type && type && best_type != type) + goto err; + best_type = target_type = IOMMU_DOMAIN_IDENTITY; + } + for_each_group_device(group, gdev) { type = best_type; if (ops->def_domain_type) { type = ops->def_domain_type(gdev->dev); - if (best_type && type && best_type != type) + if (best_type && type && best_type != type) { + /* Stick with the last driver override we saw */ + best_type = type; goto err; + } }if (dev_is_pci(gdev->dev) && to_pci_dev(gdev->dev)->untrusted) {- type = IOMMU_DOMAIN_DMA; - if (best_type && type && best_type != type) - goto err; + /* + * We don't have any way for the iommu core code to + * force arm_iommu to activate so we can't enforce + * trusted. Log it and keep going with the IDENTITY + * default domain. + */ + if (IS_ENABLED(CONFIG_ARM_DMA_USE_IOMMU)) { + dev_warn( + gdev->dev, + "PCI device is untrusted but ARM32 does not support secure IOMMU operation, continuing anyway.\n");
To within experimental error, this is dead code. The ARM DMA ops don't even understand groups, so already have the much bigger problem of being broken for any non-trivial PCI setup anyway. That's if you could even find a 32-bit SoC with both PCI(e) and a relevant IOMMU. None of those will have Thunderbolt, and I expect even fewer would be using the "external-facing" DT property (which is likely newer than they are) for any other reason.
Thanks, Robin.
+ } else { + type = IOMMU_DOMAIN_DMA; + if (best_type && type && best_type != type) + goto err; + } } best_type = type; last_dev = gdev->dev; @@ -1790,7 +1820,7 @@ static int iommu_get_default_domain_type(struct iommu_group *group, "Device needs domain type %s, but device %s in the same iommu group requires type %s - using default\n", iommu_domain_type_str(type), dev_name(last_dev), iommu_domain_type_str(best_type)); - return 0; + return best_type; }static void iommu_group_do_probe_finalize(struct device *dev)diff --git a/drivers/iommu/mtk_iommu_v1.c b/drivers/iommu/mtk_iommu_v1.c index cc3e7d53d33ad9..7c0c1d50df5f75 100644 --- a/drivers/iommu/mtk_iommu_v1.c +++ b/drivers/iommu/mtk_iommu_v1.c @@ -337,11 +337,6 @@ static struct iommu_domain mtk_iommu_v1_identity_domain = { .ops = &mtk_iommu_v1_identity_ops, };-static void mtk_iommu_v1_set_platform_dma(struct device *dev)-{ - mtk_iommu_v1_identity_attach(&mtk_iommu_v1_identity_domain, dev); -} - static int mtk_iommu_v1_map(struct iommu_domain *domain, unsigned long iova, phys_addr_t paddr, size_t pgsize, size_t pgcount, int prot, gfp_t gfp, size_t *mapped) @@ -457,11 +452,6 @@ static int mtk_iommu_v1_create_mapping(struct device *dev, struct of_phandle_arg return 0; }-static int mtk_iommu_v1_def_domain_type(struct device *dev)-{ - return IOMMU_DOMAIN_IDENTITY; -} - static struct iommu_device *mtk_iommu_v1_probe_device(struct device *dev) { struct iommu_fwspec *fwspec = dev_iommu_fwspec_get(dev); @@ -599,10 +589,8 @@ static const struct iommu_ops mtk_iommu_v1_ops = { .probe_device = mtk_iommu_v1_probe_device, .probe_finalize = mtk_iommu_v1_probe_finalize, .release_device = mtk_iommu_v1_release_device, - .def_domain_type = mtk_iommu_v1_def_domain_type, .device_group = generic_device_group, .pgsize_bitmap = MT2701_IOMMU_PAGE_SIZE, - .set_platform_dma_ops = mtk_iommu_v1_set_platform_dma, .owner = THIS_MODULE, .default_domain_ops = &(const struct iommu_domain_ops) { .attach_dev = mtk_iommu_v1_attach_device, diff --git a/drivers/iommu/rockchip-iommu.c b/drivers/iommu/rockchip-iommu.c index ebce56d6e9c634..9e1296a856ac4c 100644 --- a/drivers/iommu/rockchip-iommu.c +++ b/drivers/iommu/rockchip-iommu.c @@ -1026,13 +1026,6 @@ static struct iommu_domain rk_identity_domain = { .ops = &rk_identity_ops, };-#ifdef CONFIG_ARM-static void rk_iommu_set_platform_dma(struct device *dev) -{ - WARN_ON(rk_iommu_identity_attach(&rk_identity_domain, dev)); -} -#endif - static int rk_iommu_attach_device(struct iommu_domain *domain, struct device *dev) { @@ -1211,9 +1204,6 @@ static const struct iommu_ops rk_iommu_ops = { .probe_device = rk_iommu_probe_device, .release_device = rk_iommu_release_device, .device_group = rk_iommu_device_group, -#ifdef CONFIG_ARM - .set_platform_dma_ops = rk_iommu_set_platform_dma, -#endif .pgsize_bitmap = RK_IOMMU_PGSIZE_BITMAP, .of_xlate = rk_iommu_of_xlate, .default_domain_ops = &(const struct iommu_domain_ops) {
