[RFC 09/10] drm/tegra: Add IOMMU support

Sean Paul
2014-09-30T18:48:35Z

On Thu, Jun 26, 2014 at 4:49 PM, Thierry Reding
<thierry.reding@gmail.com> wrote:
> From: Thierry Reding <treding@nvidia.com>
>
> When an IOMMU device is available on the platform bus, allocate an IOMMU
> domain and attach the display controllers to it. The display controllers
> can then scan out non-contiguous buffers by mapping them through the
> IOMMU.
>

Hi Thierry,
A few comments from St?phane and myself that came up while we were
reviewing this for our tree.

> Signed-off-by: Thierry Reding <treding@nvidia.com>
> ---
> drivers/gpu/drm/tegra/dc.c | 21 ++++
> drivers/gpu/drm/tegra/drm.c | 17 ++++
> drivers/gpu/drm/tegra/drm.h | 3 +
> drivers/gpu/drm/tegra/fb.c | 16 ++-
> drivers/gpu/drm/tegra/gem.c | 236 +++++++++++++++++++++++++++++++++++++++-----
> drivers/gpu/drm/tegra/gem.h | 4 +
> 6 files changed, 273 insertions(+), 24 deletions(-)
>
> diff --git a/drivers/gpu/drm/tegra/dc.c b/drivers/gpu/drm/tegra/dc.c
> index afcca04f5367..0f7452d04811 100644
> --- a/drivers/gpu/drm/tegra/dc.c
> +++ b/drivers/gpu/drm/tegra/dc.c
> @@ -9,6 +9,7 @@
>
> #include <linux/clk.h>
> #include <linux/debugfs.h>
> +#include <linux/iommu.h>
> #include <linux/reset.h>
>
> #include "dc.h"
> @@ -1283,8 +1284,18 @@ static int tegra_dc_init(struct host1x_client *client)
> {
> struct drm_device *drm = dev_get_drvdata(client->parent);
> struct tegra_dc *dc = host1x_client_to_dc(client);
> + struct tegra_drm *tegra = drm->dev_private;
> int err;
>
> + if (tegra->domain) {
> + err = iommu_attach_device(tegra->domain, dc->dev);
> + if (err < 0) {
> + dev_err(dc->dev, "failed to attach to IOMMU: %d\n",
> + err);
> + return err;
> + }

[from St?phane]

shouldn't we call detach in the error paths below?

> + }
> +
> drm_crtc_init(drm, &dc->base, &tegra_crtc_funcs);
> drm_mode_crtc_set_gamma_size(&dc->base, 256);
> drm_crtc_helper_add(&dc->base, &tegra_crtc_helper_funcs);
> @@ -1318,7 +1329,9 @@ static int tegra_dc_init(struct host1x_client *client)
>
> static int tegra_dc_exit(struct host1x_client *client)
> {
> + struct drm_device *drm = dev_get_drvdata(client->parent);
> struct tegra_dc *dc = host1x_client_to_dc(client);
> + struct tegra_drm *tegra = drm->dev_private;
> int err;
>
> devm_free_irq(dc->dev, dc->irq, dc);
> @@ -1335,6 +1348,8 @@ static int tegra_dc_exit(struct host1x_client *client)
> return err;
> }
>
> + iommu_detach_device(tegra->domain, dc->dev);
> +
> return 0;
> }
>
> @@ -1462,6 +1477,12 @@ static int tegra_dc_probe(struct platform_device *pdev)
> return -ENXIO;
> }
>
> + err = iommu_attach(&pdev->dev);
> + if (err < 0) {
> + dev_err(&pdev->dev, "failed to attach to IOMMU: %d\n", err);
> + return err;
> + }
> +
> INIT_LIST_HEAD(&dc->client.list);
> dc->client.ops = &dc_client_ops;
> dc->client.dev = &pdev->dev;
> diff --git a/drivers/gpu/drm/tegra/drm.c b/drivers/gpu/drm/tegra/drm.c
> index 59736bb810cd..1d2bbafad982 100644
> --- a/drivers/gpu/drm/tegra/drm.c
> +++ b/drivers/gpu/drm/tegra/drm.c
> @@ -8,6 +8,7 @@
> */
>
> #include <linux/host1x.h>
> +#include <linux/iommu.h>
>
> #include "drm.h"
> #include "gem.h"
> @@ -33,6 +34,16 @@ static int tegra_drm_load(struct drm_device *drm, unsigned long flags)
> if (!tegra)
> return -ENOMEM;
>
> + if (iommu_present(&platform_bus_type)) {
> + tegra->domain = iommu_domain_alloc(&platform_bus_type);
> + if (IS_ERR(tegra->domain)) {
> + kfree(tegra);
> + return PTR_ERR(tegra->domain);
> + }
> +
> + drm_mm_init(&tegra->mm, 0, SZ_2G);

[from St?phane]:

none of these are freed in the error path below (iommu_domain_free and
drm_mm_takedown)

also |tegra| isn't freed either?

> + }
> +
> mutex_init(&tegra->clients_lock);
> INIT_LIST_HEAD(&tegra->clients);
> drm->dev_private = tegra;
> @@ -71,6 +82,7 @@ static int tegra_drm_load(struct drm_device *drm, unsigned long flags)
> static int tegra_drm_unload(struct drm_device *drm)
> {
> struct host1x_device *device = to_host1x_device(drm->dev);
> + struct tegra_drm *tegra = drm->dev_private;
> int err;
>
> drm_kms_helper_poll_fini(drm);
> @@ -82,6 +94,11 @@ static int tegra_drm_unload(struct drm_device *drm)
> if (err < 0)
> return err;
>
> + if (tegra->domain) {
> + iommu_domain_free(tegra->domain);
> + drm_mm_takedown(&tegra->mm);
> + }
> +
> return 0;
> }
>
> diff --git a/drivers/gpu/drm/tegra/drm.h b/drivers/gpu/drm/tegra/drm.h
> index 96d754e7b3eb..a07c796b7edc 100644
> --- a/drivers/gpu/drm/tegra/drm.h
> +++ b/drivers/gpu/drm/tegra/drm.h
> @@ -39,6 +39,9 @@ struct tegra_fbdev {
> struct tegra_drm {
> struct drm_device *drm;
>
> + struct iommu_domain *domain;
> + struct drm_mm mm;
> +
> struct mutex clients_lock;
> struct list_head clients;
>
> diff --git a/drivers/gpu/drm/tegra/fb.c b/drivers/gpu/drm/tegra/fb.c
> index 7790d43ad082..21c65dd817c3 100644
> --- a/drivers/gpu/drm/tegra/fb.c
> +++ b/drivers/gpu/drm/tegra/fb.c
> @@ -65,8 +65,12 @@ static void tegra_fb_destroy(struct drm_framebuffer *framebuffer)
> for (i = 0; i < fb->num_planes; i++) {
> struct tegra_bo *bo = fb->planes[i];
>
> - if (bo)
> + if (bo) {
> + if (bo->pages && bo->virt)
> + vunmap(bo->virt);
> +
> drm_gem_object_unreference_unlocked(&bo->gem);
> + }
> }
>
> drm_framebuffer_cleanup(framebuffer);
> @@ -252,6 +256,16 @@ static int tegra_fbdev_probe(struct drm_fb_helper *helper,
> offset = info->var.xoffset * bytes_per_pixel +
> info->var.yoffset * fb->pitches[0];
>
> + if (bo->pages) {
> + bo->vaddr = vmap(bo->pages, bo->num_pages, VM_MAP,
> + pgprot_writecombine(PAGE_KERNEL));
> + if (!bo->vaddr) {
> + dev_err(drm->dev, "failed to vmap() framebuffer\n");
> + err = -ENOMEM;
> + goto destroy;
> + }
> + }
> +
> drm->mode_config.fb_base = (resource_size_t)bo->paddr;
> info->screen_base = (void __iomem *)bo->vaddr + offset;
> info->screen_size = size;
> diff --git a/drivers/gpu/drm/tegra/gem.c b/drivers/gpu/drm/tegra/gem.c
> index c1e4e8b6e5ca..2912e61a2599 100644
> --- a/drivers/gpu/drm/tegra/gem.c
> +++ b/drivers/gpu/drm/tegra/gem.c
> @@ -14,8 +14,10 @@
> */
>
> #include <linux/dma-buf.h>
> +#include <linux/iommu.h>
> #include <drm/tegra_drm.h>
>
> +#include "drm.h"
> #include "gem.h"
>
> static inline struct tegra_bo *host1x_to_tegra_bo(struct host1x_bo *bo)
> @@ -90,14 +92,144 @@ static const struct host1x_bo_ops tegra_bo_ops = {
> .kunmap = tegra_bo_kunmap,
> };
>
> +static int iommu_map_sg(struct iommu_domain *domain, struct sg_table *sgt,
> + dma_addr_t iova, int prot)
> +{
> + unsigned long offset = 0;
> + struct scatterlist *sg;
> + unsigned int i, j;
> + int err;
> +
> + for_each_sg(sgt->sgl, sg, sgt->nents, i) {
> + dma_addr_t phys = sg_phys(sg);
> + size_t length = sg->offset;
> +
> + phys = sg_phys(sg) - sg->offset;
> + length = sg->length + sg->offset;
> +
> + err = iommu_map(domain, iova + offset, phys, length, prot);
> + if (err < 0)
> + goto unmap;
> +
> + offset += length;
> + }
> +
> + return 0;
> +
> +unmap:
> + offset = 0;
> +
> + for_each_sg(sgt->sgl, sg, i, j) {
> + size_t length = sg->length + sg->offset;
> + iommu_unmap(domain, iova + offset, length);
> + offset += length;
> + }
> +
> + return err;
> +}
> +
> +static int iommu_unmap_sg(struct iommu_domain *domain, struct sg_table *sgt,
> + dma_addr_t iova)
> +{
> + unsigned long offset = 0;
> + struct scatterlist *sg;
> + unsigned int i;
> +
> + for_each_sg(sgt->sgl, sg, sgt->nents, i) {
> + dma_addr_t phys = sg_phys(sg);
> + size_t length = sg->offset;
> +
> + phys = sg_phys(sg) - sg->offset;
> + length = sg->length + sg->offset;
> +
> + iommu_unmap(domain, iova + offset, length);
> + offset += length;
> + }
> +
> + return 0;
> +}
> +
> +static int tegra_bo_iommu_map(struct tegra_drm *tegra, struct tegra_bo *bo)
> +{
> + int prot = IOMMU_READ | IOMMU_WRITE;
> + int err;
> +
> + if (bo->mm)
> + return -EBUSY;
> +
> + bo->mm = kzalloc(sizeof(*bo->mm), GFP_KERNEL);
> + if (!bo->mm)
> + return -ENOMEM;
> +
> + err = drm_mm_insert_node_generic(&tegra->mm, bo->mm, bo->gem.size,
> + PAGE_SIZE, 0, 0, 0);
> + if (err < 0) {
> + dev_err(tegra->drm->dev, "out of virtual memory: %d\n", err);
> + return err;
> + }
> +
> + bo->paddr = bo->mm->start;
> +
> + err = iommu_map_sg(tegra->domain, bo->sgt, bo->paddr, prot);
> + if (err < 0) {
> + dev_err(tegra->drm->dev, "failed to map buffer: %d\n", err);
> + return err;
> + }
> +
> + return 0;
> +}
> +
> +static int tegra_bo_iommu_unmap(struct tegra_drm *tegra, struct tegra_bo *bo)
> +{
> + if (!bo->mm)
> + return 0;
> +
> + iommu_unmap_sg(tegra->domain, bo->sgt, bo->paddr);
> + drm_mm_remove_node(bo->mm);
> +
> + kfree(bo->mm);
> + return 0;
> +}
> +
> static void tegra_bo_destroy(struct drm_device *drm, struct tegra_bo *bo)
> {
> - dma_free_writecombine(drm->dev, bo->gem.size, bo->vaddr, bo->paddr);
> + if (!bo->pages)
> + dma_free_writecombine(drm->dev, bo->gem.size, bo->vaddr,
> + bo->paddr);
> + else
> + drm_gem_put_pages(&bo->gem, bo->pages, true, true);
> +}
> +
> +static int tegra_bo_get_pages(struct drm_device *drm, struct tegra_bo *bo,
> + size_t size)
> +{
> + bo->pages = drm_gem_get_pages(&bo->gem, GFP_KERNEL);
> + if (!bo->pages)
> + return -ENOMEM;
> +
> + bo->num_pages = size >> PAGE_SHIFT;
> +
> + return 0;
> +}
> +
> +static int tegra_bo_alloc(struct drm_device *drm, struct tegra_bo *bo,
> + size_t size)
> +{
> + bo->vaddr = dma_alloc_writecombine(drm->dev, size, &bo->paddr,
> + GFP_KERNEL | __GFP_NOWARN);
> + if (!bo->vaddr) {
> + dev_err(drm->dev, "failed to allocate buffer of size %zu\n",
> + size);
> + return -ENOMEM;
> + }
> +
> + return 0;
> }
>
> struct tegra_bo *tegra_bo_create(struct drm_device *drm, unsigned int size,
> unsigned long flags)
> {
> + struct tegra_drm *tegra = drm->dev_private;
> struct tegra_bo *bo;
> int err;
>
> @@ -108,22 +240,33 @@ struct tegra_bo *tegra_bo_create(struct drm_device *drm, unsigned int size,
> host1x_bo_init(&bo->base, &tegra_bo_ops);
> size = round_up(size, PAGE_SIZE);
>
> - bo->vaddr = dma_alloc_writecombine(drm->dev, size, &bo->paddr,
> - GFP_KERNEL | __GFP_NOWARN);
> - if (!bo->vaddr) {
> - dev_err(drm->dev, "failed to allocate buffer with size %u\n",
> - size);
> - err = -ENOMEM;
> - goto err_dma;
> - }
> -
> err = drm_gem_object_init(drm, &bo->gem, size);
> if (err)
> - goto err_init;
> + goto free;
>
> err = drm_gem_create_mmap_offset(&bo->gem);

We need to call drm_gem_free_mmap_offset if one of the calls below
fails, otherwise we'll try to free the mmap_offset on an already
destroyed bo.

Sean

> if (err)
> - goto err_mmap;
> + goto release;
> +
> + if (tegra->domain) {
> + err = tegra_bo_get_pages(drm, bo, size);
> + if (err < 0)
> + goto release;
> +
> + bo->sgt = drm_prime_pages_to_sg(bo->pages, bo->num_pages);
> + if (IS_ERR(bo->sgt)) {
> + err = PTR_ERR(bo->sgt);
> + goto release;
> + }
> +
> + err = tegra_bo_iommu_map(tegra, bo);
> + if (err < 0)
> + goto release;
> + } else {
> + err = tegra_bo_alloc(drm, bo, size);
> + if (err < 0)
> + goto release;
> + }
>
> if (flags & DRM_TEGRA_GEM_CREATE_TILED)
> bo->tiling.mode = TEGRA_BO_TILING_MODE_TILED;
> @@ -133,11 +276,10 @@ struct tegra_bo *tegra_bo_create(struct drm_device *drm, unsigned int size,
>
> return bo;
>
> -err_mmap:
> +release:
> drm_gem_object_release(&bo->gem);
> -err_init:
> tegra_bo_destroy(drm, bo);
> -err_dma:
> +free:
> kfree(bo);
>
> return ERR_PTR(err);
> @@ -172,6 +314,7 @@ err:
> static struct tegra_bo *tegra_bo_import(struct drm_device *drm,
> struct dma_buf *buf)
> {
> + struct tegra_drm *tegra = drm->dev_private;
> struct dma_buf_attachment *attach;
> struct tegra_bo *bo;
> ssize_t size;
> @@ -211,12 +354,19 @@ static struct tegra_bo *tegra_bo_import(struct drm_device *drm,
> goto detach;
> }
>
> - if (bo->sgt->nents > 1) {
> - err = -EINVAL;
> - goto detach;
> + if (tegra->domain) {
> + err = tegra_bo_iommu_map(tegra, bo);
> + if (err < 0)
> + goto detach;
> + } else {
> + if (bo->sgt->nents > 1) {
> + err = -EINVAL;
> + goto detach;
> + }
> +
> + bo->paddr = sg_dma_address(bo->sgt->sgl);
> }
>
> - bo->paddr = sg_dma_address(bo->sgt->sgl);
> bo->gem.import_attach = attach;
>
> return bo;
> @@ -239,8 +389,12 @@ free:
>
> void tegra_bo_free_object(struct drm_gem_object *gem)
> {
> + struct tegra_drm *tegra = gem->dev->dev_private;
> struct tegra_bo *bo = to_tegra_bo(gem);
>
> + if (tegra->domain)
> + tegra_bo_iommu_unmap(tegra, bo);
> +
> if (gem->import_attach) {
> dma_buf_unmap_attachment(gem->import_attach, bo->sgt,
> DMA_TO_DEVICE);
> @@ -301,7 +455,38 @@ int tegra_bo_dumb_map_offset(struct drm_file *file, struct drm_device *drm,
> return 0;
> }
>
> +static int tegra_bo_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
> +{
> + struct drm_gem_object *gem = vma->vm_private_data;
> + struct tegra_bo *bo = to_tegra_bo(gem);
> + struct page *page;
> + pgoff_t offset;
> + int err;
> +
> + if (!bo->pages)
> + return VM_FAULT_SIGBUS;
> +
> + offset = ((unsigned long)vmf->virtual_address - vma->vm_start) >> PAGE_SHIFT;
> + page = bo->pages[offset];
> +
> + err = vm_insert_page(vma, (unsigned long)vmf->virtual_address, page);
> + switch (err) {
> + case -EAGAIN:
> + case 0:
> + case -ERESTARTSYS:
> + case -EINTR:
> + case -EBUSY:
> + return VM_FAULT_NOPAGE;
> +
> + case -ENOMEM:
> + return VM_FAULT_OOM;
> + }
> +
> + return VM_FAULT_SIGBUS;
> +}
> +
> const struct vm_operations_struct tegra_bo_vm_ops = {
> + .fault = tegra_bo_fault,
> .open = drm_gem_vm_open,
> .close = drm_gem_vm_close,
> };
> @@ -316,13 +501,18 @@ int tegra_drm_mmap(struct file *file, struct vm_area_struct *vma)
> if (ret)
> return ret;
>
> + vma->vm_flags |= VM_MIXEDMAP;
> + vma->vm_flags &= ~VM_PFNMAP;
> +
> gem = vma->vm_private_data;
> bo = to_tegra_bo(gem);
>
> - ret = remap_pfn_range(vma, vma->vm_start, bo->paddr >> PAGE_SHIFT,
> - vma->vm_end - vma->vm_start, vma->vm_page_prot);
> - if (ret)
> - drm_gem_vm_close(vma);
> + if (!bo->pages) {
> + ret = remap_pfn_range(vma, vma->vm_start, bo->paddr >> PAGE_SHIFT,
> + vma->vm_end - vma->vm_start, vma->vm_page_prot);
> + if (ret)
> + drm_gem_vm_close(vma);
> + }
>
> return ret;
> }
> diff --git a/drivers/gpu/drm/tegra/gem.h b/drivers/gpu/drm/tegra/gem.h
> index 43a25c853357..c2e3f43e4b3f 100644
> --- a/drivers/gpu/drm/tegra/gem.h
> +++ b/drivers/gpu/drm/tegra/gem.h
> @@ -37,6 +37,10 @@ struct tegra_bo {
> dma_addr_t paddr;
> void *vaddr;
>
> + struct drm_mm_node *mm;
> + unsigned long num_pages;
> + struct page **pages;
> +
> struct tegra_bo_tiling tiling;
> };
>
> --
> 2.0.0
>
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