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

Sean Paul
2014-10-01T15:54:11Z

On Tue, Sep 30, 2014 at 2:48 PM, Sean Paul <seanpaul-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org> wrote:
> On Thu, Jun 26, 2014 at 4:49 PM, Thierry Reding
> <thierry.reding-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> wrote:
>> From: Thierry Reding <treding-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org>
>>
>> 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 Stéphane and myself that came up while we were
> reviewing this for our tree.
>
>> Signed-off-by: Thierry Reding <treding-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org>
>> ---
>> 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 Stéphane]
>
> 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 Stéphane]:
>
> 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);

One more thing. If tegra_bo_alloc fails, we'll have bo->vaddr == NULL
and bo->paddr == ~0 here, which causes a crash.

I posted https://lkml.org/lkml/2014/9/30/659 to check for the error
condition in the mm code, but it seems like reviewer consensus is to
check for this before calling free.

As such, we'll need to make sure bo->vaddr != NULL before calling
dma_free_writecombine to avoid this situation.

Would you prefer I send a patch up to fix this separately, or would
you like to roll this into your next version?

Sean

>> + 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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