On Mon, Nov 04, 2013 at 05:57:39AM -0800, Thomas Hellstrom wrote:
> The code handles three different cases:
> 1) physical page addresses. The ttm page array is used.
> 2) DMA subsystem addresses. A scatter-gather list is used.
> 3) Coherent pages. The ttm dma pool is used, together with the dma_ttm
> array os dma_addr_t
> 
> Signed-off-by: Thomas Hellstrom <thellst...@vmware.com>
> Reviewed-by: Jakob Bornecrantz <ja...@vmware.com>

I looked at it from the TTM DMA perspective and it looks OK for me.

> ---
>  drivers/gpu/drm/vmwgfx/vmwgfx_buffer.c |  379 
> ++++++++++++++++++++++++++++++--
>  drivers/gpu/drm/vmwgfx/vmwgfx_drv.c    |   87 +++++++-
>  drivers/gpu/drm/vmwgfx/vmwgfx_drv.h    |   98 ++++++++-
>  drivers/gpu/drm/vmwgfx/vmwgfx_gmr.c    |  150 ++++++-------
>  4 files changed, 620 insertions(+), 94 deletions(-)
> 
> diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_buffer.c 
> b/drivers/gpu/drm/vmwgfx/vmwgfx_buffer.c
> index 96dc84d..7776e6f 100644
> --- a/drivers/gpu/drm/vmwgfx/vmwgfx_buffer.c
> +++ b/drivers/gpu/drm/vmwgfx/vmwgfx_buffer.c
> @@ -141,37 +141,374 @@ struct ttm_placement vmw_srf_placement = {
>  };
>  
>  struct vmw_ttm_tt {
> -     struct ttm_tt ttm;
> +     struct ttm_dma_tt dma_ttm;
>       struct vmw_private *dev_priv;
>       int gmr_id;
> +     struct sg_table sgt;
> +     struct vmw_sg_table vsgt;
> +     uint64_t sg_alloc_size;
> +     bool mapped;
>  };
>  
> +/**
> + * Helper functions to advance a struct vmw_piter iterator.
> + *
> + * @viter: Pointer to the iterator.
> + *
> + * These functions return false if past the end of the list,
> + * true otherwise. Functions are selected depending on the current
> + * DMA mapping mode.
> + */
> +static bool __vmw_piter_non_sg_next(struct vmw_piter *viter)
> +{
> +     return ++(viter->i) < viter->num_pages;
> +}
> +
> +static bool __vmw_piter_sg_next(struct vmw_piter *viter)
> +{
> +     return __sg_page_iter_next(&viter->iter);
> +}
> +
> +
> +/**
> + * Helper functions to return a pointer to the current page.
> + *
> + * @viter: Pointer to the iterator
> + *
> + * These functions return a pointer to the page currently
> + * pointed to by @viter. Functions are selected depending on the
> + * current mapping mode.
> + */
> +static struct page *__vmw_piter_non_sg_page(struct vmw_piter *viter)
> +{
> +     return viter->pages[viter->i];
> +}
> +
> +static struct page *__vmw_piter_sg_page(struct vmw_piter *viter)
> +{
> +     return sg_page_iter_page(&viter->iter);
> +}
> +
> +
> +/**
> + * Helper functions to return the DMA address of the current page.
> + *
> + * @viter: Pointer to the iterator
> + *
> + * These functions return the DMA address of the page currently
> + * pointed to by @viter. Functions are selected depending on the
> + * current mapping mode.
> + */
> +static dma_addr_t __vmw_piter_phys_addr(struct vmw_piter *viter)
> +{
> +     return page_to_phys(viter->pages[viter->i]);
> +}
> +
> +static dma_addr_t __vmw_piter_dma_addr(struct vmw_piter *viter)
> +{
> +     return viter->addrs[viter->i];
> +}
> +
> +static dma_addr_t __vmw_piter_sg_addr(struct vmw_piter *viter)
> +{
> +     return sg_page_iter_dma_address(&viter->iter);
> +}
> +
> +
> +/**
> + * vmw_piter_start - Initialize a struct vmw_piter.
> + *
> + * @viter: Pointer to the iterator to initialize
> + * @vsgt: Pointer to a struct vmw_sg_table to initialize from
> + *
> + * Note that we're following the convention of __sg_page_iter_start, so that
> + * the iterator doesn't point to a valid page after initialization; it has
> + * to be advanced one step first.
> + */
> +void vmw_piter_start(struct vmw_piter *viter, const struct vmw_sg_table 
> *vsgt,
> +                  unsigned long p_offset)
> +{
> +     viter->i = p_offset - 1;
> +     viter->num_pages = vsgt->num_pages;
> +     switch (vsgt->mode) {
> +     case vmw_dma_phys:
> +             viter->next = &__vmw_piter_non_sg_next;
> +             viter->dma_address = &__vmw_piter_phys_addr;
> +             viter->page = &__vmw_piter_non_sg_page;
> +             viter->pages = vsgt->pages;
> +             break;
> +     case vmw_dma_alloc_coherent:
> +             viter->next = &__vmw_piter_non_sg_next;
> +             viter->dma_address = &__vmw_piter_dma_addr;
> +             viter->page = &__vmw_piter_non_sg_page;
> +             viter->addrs = vsgt->addrs;
> +             break;
> +     case vmw_dma_map_populate:
> +     case vmw_dma_map_bind:
> +             viter->next = &__vmw_piter_sg_next;
> +             viter->dma_address = &__vmw_piter_sg_addr;
> +             viter->page = &__vmw_piter_sg_page;
> +             __sg_page_iter_start(&viter->iter, vsgt->sgt->sgl,
> +                                  vsgt->sgt->orig_nents, p_offset);
> +             break;
> +     default:
> +             BUG();
> +     }
> +}
> +
> +/**
> + * vmw_ttm_unmap_from_dma - unmap  device addresses previsouly mapped for
> + * TTM pages
> + *
> + * @vmw_tt: Pointer to a struct vmw_ttm_backend
> + *
> + * Used to free dma mappings previously mapped by vmw_ttm_map_for_dma.
> + */
> +static void vmw_ttm_unmap_from_dma(struct vmw_ttm_tt *vmw_tt)
> +{
> +     struct device *dev = vmw_tt->dev_priv->dev->dev;
> +
> +     dma_unmap_sg(dev, vmw_tt->sgt.sgl, vmw_tt->sgt.nents,
> +             DMA_BIDIRECTIONAL);
> +     vmw_tt->sgt.nents = vmw_tt->sgt.orig_nents;
> +}
> +
> +/**
> + * vmw_ttm_map_for_dma - map TTM pages to get device addresses
> + *
> + * @vmw_tt: Pointer to a struct vmw_ttm_backend
> + *
> + * This function is used to get device addresses from the kernel DMA layer.
> + * However, it's violating the DMA API in that when this operation has been
> + * performed, it's illegal for the CPU to write to the pages without first
> + * unmapping the DMA mappings, or calling dma_sync_sg_for_cpu(). It is
> + * therefore only legal to call this function if we know that the function
> + * dma_sync_sg_for_cpu() is a NOP, and dma_sync_sg_for_device() is at most
> + * a CPU write buffer flush.
> + */
> +static int vmw_ttm_map_for_dma(struct vmw_ttm_tt *vmw_tt)
> +{
> +     struct device *dev = vmw_tt->dev_priv->dev->dev;
> +     int ret;
> +
> +     ret = dma_map_sg(dev, vmw_tt->sgt.sgl, vmw_tt->sgt.orig_nents,
> +                      DMA_BIDIRECTIONAL);
> +     if (unlikely(ret == 0))
> +             return -ENOMEM;
> +
> +     vmw_tt->sgt.nents = ret;
> +
> +     return 0;
> +}
> +
> +/**
> + * vmw_ttm_map_dma - Make sure TTM pages are visible to the device
> + *
> + * @vmw_tt: Pointer to a struct vmw_ttm_tt
> + *
> + * Select the correct function for and make sure the TTM pages are
> + * visible to the device. Allocate storage for the device mappings.
> + * If a mapping has already been performed, indicated by the storage
> + * pointer being non NULL, the function returns success.
> + */
> +static int vmw_ttm_map_dma(struct vmw_ttm_tt *vmw_tt)
> +{
> +     struct vmw_private *dev_priv = vmw_tt->dev_priv;
> +     struct ttm_mem_global *glob = vmw_mem_glob(dev_priv);
> +     struct vmw_sg_table *vsgt = &vmw_tt->vsgt;
> +     struct vmw_piter iter;
> +     dma_addr_t old;
> +     int ret = 0;
> +     static size_t sgl_size;
> +     static size_t sgt_size;
> +
> +     if (vmw_tt->mapped)
> +             return 0;
> +
> +     vsgt->mode = dev_priv->map_mode;
> +     vsgt->pages = vmw_tt->dma_ttm.ttm.pages;
> +     vsgt->num_pages = vmw_tt->dma_ttm.ttm.num_pages;
> +     vsgt->addrs = vmw_tt->dma_ttm.dma_address;
> +     vsgt->sgt = &vmw_tt->sgt;
> +
> +     switch (dev_priv->map_mode) {
> +     case vmw_dma_map_bind:
> +     case vmw_dma_map_populate:
> +             if (unlikely(!sgl_size)) {
> +                     sgl_size = ttm_round_pot(sizeof(struct scatterlist));
> +                     sgt_size = ttm_round_pot(sizeof(struct sg_table));
> +             }
> +             vmw_tt->sg_alloc_size = sgt_size + sgl_size * vsgt->num_pages;
> +             ret = ttm_mem_global_alloc(glob, vmw_tt->sg_alloc_size, false,
> +                                        true);
> +             if (unlikely(ret != 0))
> +                     return ret;
> +
> +             ret = sg_alloc_table_from_pages(&vmw_tt->sgt, vsgt->pages,
> +                                             vsgt->num_pages, 0,
> +                                             (unsigned long)
> +                                             vsgt->num_pages << PAGE_SHIFT,
> +                                             GFP_KERNEL);
> +             if (unlikely(ret != 0))
> +                     goto out_sg_alloc_fail;
> +
> +             if (vsgt->num_pages > vmw_tt->sgt.nents) {
> +                     uint64_t over_alloc =
> +                             sgl_size * (vsgt->num_pages -
> +                                         vmw_tt->sgt.nents);
> +
> +                     ttm_mem_global_free(glob, over_alloc);
> +                     vmw_tt->sg_alloc_size -= over_alloc;
> +             }
> +
> +             ret = vmw_ttm_map_for_dma(vmw_tt);
> +             if (unlikely(ret != 0))
> +                     goto out_map_fail;
> +
> +             break;
> +     default:
> +             break;
> +     }
> +
> +     old = ~((dma_addr_t) 0);
> +     vmw_tt->vsgt.num_regions = 0;
> +     for (vmw_piter_start(&iter, vsgt, 0); vmw_piter_next(&iter);) {
> +             dma_addr_t cur = vmw_piter_dma_addr(&iter);
> +
> +             if (cur != old + PAGE_SIZE)
> +                     vmw_tt->vsgt.num_regions++;
> +             old = cur;
> +     }
> +
> +     vmw_tt->mapped = true;
> +     return 0;
> +
> +out_map_fail:
> +     sg_free_table(vmw_tt->vsgt.sgt);
> +     vmw_tt->vsgt.sgt = NULL;
> +out_sg_alloc_fail:
> +     ttm_mem_global_free(glob, vmw_tt->sg_alloc_size);
> +     return ret;
> +}
> +
> +/**
> + * vmw_ttm_unmap_dma - Tear down any TTM page device mappings
> + *
> + * @vmw_tt: Pointer to a struct vmw_ttm_tt
> + *
> + * Tear down any previously set up device DMA mappings and free
> + * any storage space allocated for them. If there are no mappings set up,
> + * this function is a NOP.
> + */
> +static void vmw_ttm_unmap_dma(struct vmw_ttm_tt *vmw_tt)
> +{
> +     struct vmw_private *dev_priv = vmw_tt->dev_priv;
> +
> +     if (!vmw_tt->vsgt.sgt)
> +             return;
> +
> +     switch (dev_priv->map_mode) {
> +     case vmw_dma_map_bind:
> +     case vmw_dma_map_populate:
> +             vmw_ttm_unmap_from_dma(vmw_tt);
> +             sg_free_table(vmw_tt->vsgt.sgt);
> +             vmw_tt->vsgt.sgt = NULL;
> +             ttm_mem_global_free(vmw_mem_glob(dev_priv),
> +                                 vmw_tt->sg_alloc_size);
> +             break;
> +     default:
> +             break;
> +     }
> +     vmw_tt->mapped = false;
> +}
> +
>  static int vmw_ttm_bind(struct ttm_tt *ttm, struct ttm_mem_reg *bo_mem)
>  {
> -     struct vmw_ttm_tt *vmw_be = container_of(ttm, struct vmw_ttm_tt, ttm);
> +     struct vmw_ttm_tt *vmw_be =
> +             container_of(ttm, struct vmw_ttm_tt, dma_ttm.ttm);
> +     int ret;
> +
> +     ret = vmw_ttm_map_dma(vmw_be);
> +     if (unlikely(ret != 0))
> +             return ret;
>  
>       vmw_be->gmr_id = bo_mem->start;
>  
> -     return vmw_gmr_bind(vmw_be->dev_priv, ttm->pages,
> +     return vmw_gmr_bind(vmw_be->dev_priv, &vmw_be->vsgt,
>                           ttm->num_pages, vmw_be->gmr_id);
>  }
>  
>  static int vmw_ttm_unbind(struct ttm_tt *ttm)
>  {
> -     struct vmw_ttm_tt *vmw_be = container_of(ttm, struct vmw_ttm_tt, ttm);
> +     struct vmw_ttm_tt *vmw_be =
> +             container_of(ttm, struct vmw_ttm_tt, dma_ttm.ttm);
>  
>       vmw_gmr_unbind(vmw_be->dev_priv, vmw_be->gmr_id);
> +
> +     if (vmw_be->dev_priv->map_mode == vmw_dma_map_bind)
> +             vmw_ttm_unmap_dma(vmw_be);
> +
>       return 0;
>  }
>  
>  static void vmw_ttm_destroy(struct ttm_tt *ttm)
>  {
> -     struct vmw_ttm_tt *vmw_be = container_of(ttm, struct vmw_ttm_tt, ttm);
> -
> -     ttm_tt_fini(ttm);
> +     struct vmw_ttm_tt *vmw_be =
> +             container_of(ttm, struct vmw_ttm_tt, dma_ttm.ttm);
> +
> +     vmw_ttm_unmap_dma(vmw_be);
> +     if (vmw_be->dev_priv->map_mode == vmw_dma_alloc_coherent)
> +             ttm_dma_tt_fini(&vmw_be->dma_ttm);
> +     else
> +             ttm_tt_fini(ttm);
>       kfree(vmw_be);
>  }
>  
> +static int vmw_ttm_populate(struct ttm_tt *ttm)
> +{
> +     struct vmw_ttm_tt *vmw_tt =
> +             container_of(ttm, struct vmw_ttm_tt, dma_ttm.ttm);
> +     struct vmw_private *dev_priv = vmw_tt->dev_priv;
> +     struct ttm_mem_global *glob = vmw_mem_glob(dev_priv);
> +     int ret;
> +
> +     if (ttm->state != tt_unpopulated)
> +             return 0;
> +
> +     if (dev_priv->map_mode == vmw_dma_alloc_coherent) {
> +             size_t size =
> +                     ttm_round_pot(ttm->num_pages * sizeof(dma_addr_t));
> +             ret = ttm_mem_global_alloc(glob, size, false, true);
> +             if (unlikely(ret != 0))
> +                     return ret;
> +
> +             ret = ttm_dma_populate(&vmw_tt->dma_ttm, dev_priv->dev->dev);
> +             if (unlikely(ret != 0))
> +                     ttm_mem_global_free(glob, size);
> +     } else
> +             ret = ttm_pool_populate(ttm);
> +
> +     return ret;
> +}
> +
> +static void vmw_ttm_unpopulate(struct ttm_tt *ttm)
> +{
> +     struct vmw_ttm_tt *vmw_tt = container_of(ttm, struct vmw_ttm_tt,
> +                                              dma_ttm.ttm);
> +     struct vmw_private *dev_priv = vmw_tt->dev_priv;
> +     struct ttm_mem_global *glob = vmw_mem_glob(dev_priv);
> +
> +     vmw_ttm_unmap_dma(vmw_tt);
> +     if (dev_priv->map_mode == vmw_dma_alloc_coherent) {
> +             size_t size =
> +                     ttm_round_pot(ttm->num_pages * sizeof(dma_addr_t));
> +
> +             ttm_dma_unpopulate(&vmw_tt->dma_ttm, dev_priv->dev->dev);
> +             ttm_mem_global_free(glob, size);
> +     } else
> +             ttm_pool_unpopulate(ttm);
> +}
> +
>  static struct ttm_backend_func vmw_ttm_func = {
>       .bind = vmw_ttm_bind,
>       .unbind = vmw_ttm_unbind,
> @@ -183,20 +520,28 @@ struct ttm_tt *vmw_ttm_tt_create(struct ttm_bo_device 
> *bdev,
>                                struct page *dummy_read_page)
>  {
>       struct vmw_ttm_tt *vmw_be;
> +     int ret;
>  
> -     vmw_be = kmalloc(sizeof(*vmw_be), GFP_KERNEL);
> +     vmw_be = kzalloc(sizeof(*vmw_be), GFP_KERNEL);
>       if (!vmw_be)
>               return NULL;
>  
> -     vmw_be->ttm.func = &vmw_ttm_func;
> +     vmw_be->dma_ttm.ttm.func = &vmw_ttm_func;
>       vmw_be->dev_priv = container_of(bdev, struct vmw_private, bdev);
>  
> -     if (ttm_tt_init(&vmw_be->ttm, bdev, size, page_flags, dummy_read_page)) 
> {
> -             kfree(vmw_be);
> -             return NULL;
> -     }
> -
> -     return &vmw_be->ttm;
> +     if (vmw_be->dev_priv->map_mode == vmw_dma_alloc_coherent)
> +             ret = ttm_dma_tt_init(&vmw_be->dma_ttm, bdev, size, page_flags,
> +                                   dummy_read_page);
> +     else
> +             ret = ttm_tt_init(&vmw_be->dma_ttm.ttm, bdev, size, page_flags,
> +                               dummy_read_page);
> +     if (unlikely(ret != 0))
> +             goto out_no_init;
> +
> +     return &vmw_be->dma_ttm.ttm;
> +out_no_init:
> +     kfree(vmw_be);
> +     return NULL;
>  }
>  
>  int vmw_invalidate_caches(struct ttm_bo_device *bdev, uint32_t flags)
> @@ -332,8 +677,8 @@ static int vmw_sync_obj_wait(void *sync_obj, bool lazy, 
> bool interruptible)
>  
>  struct ttm_bo_driver vmw_bo_driver = {
>       .ttm_tt_create = &vmw_ttm_tt_create,
> -     .ttm_tt_populate = &ttm_pool_populate,
> -     .ttm_tt_unpopulate = &ttm_pool_unpopulate,
> +     .ttm_tt_populate = &vmw_ttm_populate,
> +     .ttm_tt_unpopulate = &vmw_ttm_unpopulate,
>       .invalidate_caches = vmw_invalidate_caches,
>       .init_mem_type = vmw_init_mem_type,
>       .evict_flags = vmw_evict_flags,
> diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_drv.c 
> b/drivers/gpu/drm/vmwgfx/vmwgfx_drv.c
> index 1a90f0a..0b5c781 100644
> --- a/drivers/gpu/drm/vmwgfx/vmwgfx_drv.c
> +++ b/drivers/gpu/drm/vmwgfx/vmwgfx_drv.c
> @@ -32,6 +32,7 @@
>  #include <drm/ttm/ttm_bo_driver.h>
>  #include <drm/ttm/ttm_object.h>
>  #include <drm/ttm/ttm_module.h>
> +#include <linux/dma_remapping.h>
>  
>  #define VMWGFX_DRIVER_NAME "vmwgfx"
>  #define VMWGFX_DRIVER_DESC "Linux drm driver for VMware graphics devices"
> @@ -185,6 +186,9 @@ static struct pci_device_id vmw_pci_id_list[] = {
>  MODULE_DEVICE_TABLE(pci, vmw_pci_id_list);
>  
>  static int enable_fbdev = IS_ENABLED(CONFIG_DRM_VMWGFX_FBCON);
> +static int vmw_force_iommu;
> +static int vmw_restrict_iommu;
> +static int vmw_force_coherent;
>  
>  static int vmw_probe(struct pci_dev *, const struct pci_device_id *);
>  static void vmw_master_init(struct vmw_master *);
> @@ -193,6 +197,13 @@ static int vmwgfx_pm_notifier(struct notifier_block *nb, 
> unsigned long val,
>  
>  MODULE_PARM_DESC(enable_fbdev, "Enable vmwgfx fbdev");
>  module_param_named(enable_fbdev, enable_fbdev, int, 0600);
> +MODULE_PARM_DESC(force_dma_api, "Force using the DMA API for TTM pages");
> +module_param_named(force_dma_api, vmw_force_iommu, int, 0600);
> +MODULE_PARM_DESC(restrict_iommu, "Try to limit IOMMU usage for TTM pages");
> +module_param_named(restrict_iommu, vmw_restrict_iommu, int, 0600);
> +MODULE_PARM_DESC(force_coherent, "Force coherent TTM pages");
> +module_param_named(force_coherent, vmw_force_coherent, int, 0600);
> +
>  
>  static void vmw_print_capabilities(uint32_t capabilities)
>  {
> @@ -427,12 +438,78 @@ static void vmw_get_initial_size(struct vmw_private 
> *dev_priv)
>       dev_priv->initial_height = height;
>  }
>  
> +/**
> + * vmw_dma_select_mode - Determine how DMA mappings should be set up for this
> + * system.
> + *
> + * @dev_priv: Pointer to a struct vmw_private
> + *
> + * This functions tries to determine the IOMMU setup and what actions
> + * need to be taken by the driver to make system pages visible to the
> + * device.
> + * If this function decides that DMA is not possible, it returns -EINVAL.
> + * The driver may then try to disable features of the device that require
> + * DMA.
> + */
> +static int vmw_dma_select_mode(struct vmw_private *dev_priv)
> +{
> +     const struct dma_map_ops *dma_ops = get_dma_ops(dev_priv->dev->dev);
> +     static const char *names[vmw_dma_map_max] = {
> +             [vmw_dma_phys] = "Using physical TTM page addresses.",
> +             [vmw_dma_alloc_coherent] = "Using coherent TTM pages.",
> +             [vmw_dma_map_populate] = "Keeping DMA mappings.",
> +             [vmw_dma_map_bind] = "Giving up DMA mappings early."};
> +
> +#ifdef CONFIG_INTEL_IOMMU
> +     if (intel_iommu_enabled) {
> +             dev_priv->map_mode = vmw_dma_map_populate;
> +             goto out_fixup;
> +     }
> +#endif
> +
> +     if (!(vmw_force_iommu || vmw_force_coherent)) {
> +             dev_priv->map_mode = vmw_dma_phys;
> +             DRM_INFO("DMA map mode: %s\n", names[dev_priv->map_mode]);
> +             return 0;
> +     }
> +
> +     dev_priv->map_mode = vmw_dma_map_populate;
> +
> +     if (dma_ops->sync_single_for_cpu)
> +             dev_priv->map_mode = vmw_dma_alloc_coherent;
> +#ifdef CONFIG_SWIOTLB
> +     if (swiotlb_nr_tbl() == 0)
> +             dev_priv->map_mode = vmw_dma_map_populate;
> +#endif
> +
> +out_fixup:
> +     if (dev_priv->map_mode == vmw_dma_map_populate &&
> +         vmw_restrict_iommu)
> +             dev_priv->map_mode = vmw_dma_map_bind;
> +
> +     if (vmw_force_coherent)
> +             dev_priv->map_mode = vmw_dma_alloc_coherent;
> +
> +#if !defined(CONFIG_SWIOTLB) && !defined(CONFIG_INTEL_IOMMU)
> +     /*
> +      * No coherent page pool
> +      */
> +     if (dev_priv->map_mode == vmw_dma_alloc_coherent)
> +             return -EINVAL;
> +#endif
> +
> +     DRM_INFO("DMA map mode: %s\n", names[dev_priv->map_mode]);
> +
> +     return 0;
> +}
> +
>  static int vmw_driver_load(struct drm_device *dev, unsigned long chipset)
>  {
>       struct vmw_private *dev_priv;
>       int ret;
>       uint32_t svga_id;
>       enum vmw_res_type i;
> +     bool refuse_dma = false;
>  
>       dev_priv = kzalloc(sizeof(*dev_priv), GFP_KERNEL);
>       if (unlikely(dev_priv == NULL)) {
> @@ -481,6 +558,11 @@ static int vmw_driver_load(struct drm_device *dev, 
> unsigned long chipset)
>       }
>  
>       dev_priv->capabilities = vmw_read(dev_priv, SVGA_REG_CAPABILITIES);
> +     ret = vmw_dma_select_mode(dev_priv);
> +     if (unlikely(ret != 0)) {
> +             DRM_INFO("Restricting capabilities due to IOMMU setup.\n");
> +             refuse_dma = true;
> +     }
>  
>       dev_priv->vram_size = vmw_read(dev_priv, SVGA_REG_VRAM_SIZE);
>       dev_priv->mmio_size = vmw_read(dev_priv, SVGA_REG_MEM_SIZE);
> @@ -558,8 +640,9 @@ static int vmw_driver_load(struct drm_device *dev, 
> unsigned long chipset)
>       }
>  
>       dev_priv->has_gmr = true;
> -     if (ttm_bo_init_mm(&dev_priv->bdev, VMW_PL_GMR,
> -                        dev_priv->max_gmr_ids) != 0) {
> +     if (((dev_priv->capabilities & (SVGA_CAP_GMR | SVGA_CAP_GMR2)) == 0) ||
> +         refuse_dma || ttm_bo_init_mm(&dev_priv->bdev, VMW_PL_GMR,
> +                                      dev_priv->max_gmr_ids) != 0) {
>               DRM_INFO("No GMR memory available. "
>                        "Graphics memory resources are very limited.\n");
>               dev_priv->has_gmr = false;
> diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_drv.h 
> b/drivers/gpu/drm/vmwgfx/vmwgfx_drv.h
> index 150ec64..e401d5d 100644
> --- a/drivers/gpu/drm/vmwgfx/vmwgfx_drv.h
> +++ b/drivers/gpu/drm/vmwgfx/vmwgfx_drv.h
> @@ -177,6 +177,58 @@ struct vmw_res_cache_entry {
>       struct vmw_resource_val_node *node;
>  };
>  
> +/**
> + * enum vmw_dma_map_mode - indicate how to perform TTM page dma mappings.
> + */
> +enum vmw_dma_map_mode {
> +     vmw_dma_phys,           /* Use physical page addresses */
> +     vmw_dma_alloc_coherent, /* Use TTM coherent pages */
> +     vmw_dma_map_populate,   /* Unmap from DMA just after unpopulate */
> +     vmw_dma_map_bind,       /* Unmap from DMA just before unbind */
> +     vmw_dma_map_max
> +};
> +
> +/**
> + * struct vmw_sg_table - Scatter/gather table for binding, with additional
> + * device-specific information.
> + *
> + * @sgt: Pointer to a struct sg_table with binding information
> + * @num_regions: Number of regions with device-address contigous pages
> + */
> +struct vmw_sg_table {
> +     enum vmw_dma_map_mode mode;
> +     struct page **pages;
> +     const dma_addr_t *addrs;
> +     struct sg_table *sgt;
> +     unsigned long num_regions;
> +     unsigned long num_pages;
> +};
> +
> +/**
> + * struct vmw_piter - Page iterator that iterates over a list of pages
> + * and DMA addresses that could be either a scatter-gather list or
> + * arrays
> + *
> + * @pages: Array of page pointers to the pages.
> + * @addrs: DMA addresses to the pages if coherent pages are used.
> + * @iter: Scatter-gather page iterator. Current position in SG list.
> + * @i: Current position in arrays.
> + * @num_pages: Number of pages total.
> + * @next: Function to advance the iterator. Returns false if past the list
> + * of pages, true otherwise.
> + * @dma_address: Function to return the DMA address of the current page.
> + */
> +struct vmw_piter {
> +     struct page **pages;
> +     const dma_addr_t *addrs;
> +     struct sg_page_iter iter;
> +     unsigned long i;
> +     unsigned long num_pages;
> +     bool (*next)(struct vmw_piter *);
> +     dma_addr_t (*dma_address)(struct vmw_piter *);
> +     struct page *(*page)(struct vmw_piter *);
> +};
> +
>  struct vmw_sw_context{
>       struct drm_open_hash res_ht;
>       bool res_ht_initialized;
> @@ -358,6 +410,11 @@ struct vmw_private {
>  
>       struct list_head res_lru[vmw_res_max];
>       uint32_t used_memory_size;
> +
> +     /*
> +      * DMA mapping stuff.
> +      */
> +     enum vmw_dma_map_mode map_mode;
>  };
>  
>  static inline struct vmw_surface *vmw_res_to_srf(struct vmw_resource *res)
> @@ -405,7 +462,7 @@ void vmw_3d_resource_dec(struct vmw_private *dev_priv, 
> bool hide_svga);
>   */
>  
>  extern int vmw_gmr_bind(struct vmw_private *dev_priv,
> -                     struct page *pages[],
> +                     const struct vmw_sg_table *vsgt,
>                       unsigned long num_pages,
>                       int gmr_id);
>  extern void vmw_gmr_unbind(struct vmw_private *dev_priv, int gmr_id);
> @@ -568,6 +625,45 @@ extern struct ttm_placement vmw_evictable_placement;
>  extern struct ttm_placement vmw_srf_placement;
>  extern struct ttm_bo_driver vmw_bo_driver;
>  extern int vmw_dma_quiescent(struct drm_device *dev);
> +extern void vmw_piter_start(struct vmw_piter *viter,
> +                         const struct vmw_sg_table *vsgt,
> +                         unsigned long p_offs);
> +
> +/**
> + * vmw_piter_next - Advance the iterator one page.
> + *
> + * @viter: Pointer to the iterator to advance.
> + *
> + * Returns false if past the list of pages, true otherwise.
> + */
> +static inline bool vmw_piter_next(struct vmw_piter *viter)
> +{
> +     return viter->next(viter);
> +}
> +
> +/**
> + * vmw_piter_dma_addr - Return the DMA address of the current page.
> + *
> + * @viter: Pointer to the iterator
> + *
> + * Returns the DMA address of the page pointed to by @viter.
> + */
> +static inline dma_addr_t vmw_piter_dma_addr(struct vmw_piter *viter)
> +{
> +     return viter->dma_address(viter);
> +}
> +
> +/**
> + * vmw_piter_page - Return a pointer to the current page.
> + *
> + * @viter: Pointer to the iterator
> + *
> + * Returns the DMA address of the page pointed to by @viter.
> + */
> +static inline struct page *vmw_piter_page(struct vmw_piter *viter)
> +{
> +     return viter->page(viter);
> +}
>  
>  /**
>   * Command submission - vmwgfx_execbuf.c
> diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_gmr.c 
> b/drivers/gpu/drm/vmwgfx/vmwgfx_gmr.c
> index 1a0bf07..6d09523 100644
> --- a/drivers/gpu/drm/vmwgfx/vmwgfx_gmr.c
> +++ b/drivers/gpu/drm/vmwgfx/vmwgfx_gmr.c
> @@ -32,9 +32,11 @@
>  #define VMW_PPN_SIZE (sizeof(unsigned long))
>  /* A future safe maximum remap size. */
>  #define VMW_PPN_PER_REMAP ((31 * 1024) / VMW_PPN_SIZE)
> +#define DMA_ADDR_INVALID ((dma_addr_t) 0)
> +#define DMA_PAGE_INVALID 0UL
>  
>  static int vmw_gmr2_bind(struct vmw_private *dev_priv,
> -                      struct page *pages[],
> +                      struct vmw_piter *iter,
>                        unsigned long num_pages,
>                        int gmr_id)
>  {
> @@ -81,11 +83,13 @@ static int vmw_gmr2_bind(struct vmw_private *dev_priv,
>  
>               for (i = 0; i < nr; ++i) {
>                       if (VMW_PPN_SIZE <= 4)
> -                             *cmd = page_to_pfn(*pages++);
> +                             *cmd = vmw_piter_dma_addr(iter) >> PAGE_SHIFT;
>                       else
> -                             *((uint64_t *)cmd) = page_to_pfn(*pages++);
> +                             *((uint64_t *)cmd) = vmw_piter_dma_addr(iter) >>
> +                                     PAGE_SHIFT;
>  
>                       cmd += VMW_PPN_SIZE / sizeof(*cmd);
> +                     vmw_piter_next(iter);
>               }
>  
>               num_pages -= nr;
> @@ -120,22 +124,54 @@ static void vmw_gmr2_unbind(struct vmw_private 
> *dev_priv,
>       vmw_fifo_commit(dev_priv, define_size);
>  }
>  
> +
> +static void vmw_gmr_free_descriptors(struct device *dev, dma_addr_t desc_dma,
> +                                  struct list_head *desc_pages)
> +{
> +     struct page *page, *next;
> +     struct svga_guest_mem_descriptor *page_virtual;
> +     unsigned int desc_per_page = PAGE_SIZE /
> +             sizeof(struct svga_guest_mem_descriptor) - 1;
> +
> +     if (list_empty(desc_pages))
> +             return;
> +
> +     list_for_each_entry_safe(page, next, desc_pages, lru) {
> +             list_del_init(&page->lru);
> +
> +             if (likely(desc_dma != DMA_ADDR_INVALID)) {
> +                     dma_unmap_page(dev, desc_dma, PAGE_SIZE,
> +                                    DMA_TO_DEVICE);
> +             }
> +
> +             page_virtual = kmap_atomic(page);
> +             desc_dma = page_virtual[desc_per_page].ppn << PAGE_SHIFT;
> +             kunmap_atomic(page_virtual);
> +
> +             __free_page(page);
> +     }
> +}
> +
>  /**
>   * FIXME: Adjust to the ttm lowmem / highmem storage to minimize
>   * the number of used descriptors.
> + *
>   */
>  
> -static int vmw_gmr_build_descriptors(struct list_head *desc_pages,
> -                                  struct page *pages[],
> -                                  unsigned long num_pages)
> +static int vmw_gmr_build_descriptors(struct device *dev,
> +                                  struct list_head *desc_pages,
> +                                  struct vmw_piter *iter,
> +                                  unsigned long num_pages,
> +                                  dma_addr_t *first_dma)
>  {
> -     struct page *page, *next;
> +     struct page *page;
>       struct svga_guest_mem_descriptor *page_virtual = NULL;
>       struct svga_guest_mem_descriptor *desc_virtual = NULL;
>       unsigned int desc_per_page;
>       unsigned long prev_pfn;
>       unsigned long pfn;
>       int ret;
> +     dma_addr_t desc_dma;
>  
>       desc_per_page = PAGE_SIZE /
>           sizeof(struct svga_guest_mem_descriptor) - 1;
> @@ -148,23 +184,12 @@ static int vmw_gmr_build_descriptors(struct list_head 
> *desc_pages,
>               }
>  
>               list_add_tail(&page->lru, desc_pages);
> -
> -             /*
> -              * Point previous page terminating descriptor to this
> -              * page before unmapping it.
> -              */
> -
> -             if (likely(page_virtual != NULL)) {
> -                     desc_virtual->ppn = page_to_pfn(page);
> -                     kunmap_atomic(page_virtual);
> -             }
> -
>               page_virtual = kmap_atomic(page);
>               desc_virtual = page_virtual - 1;
>               prev_pfn = ~(0UL);
>  
>               while (likely(num_pages != 0)) {
> -                     pfn = page_to_pfn(*pages);
> +                     pfn = vmw_piter_dma_addr(iter) >> PAGE_SHIFT;
>  
>                       if (pfn != prev_pfn + 1) {
>  
> @@ -181,104 +206,81 @@ static int vmw_gmr_build_descriptors(struct list_head 
> *desc_pages,
>                       }
>                       prev_pfn = pfn;
>                       --num_pages;
> -                     ++pages;
> +                     vmw_piter_next(iter);
>               }
>  
> -             (++desc_virtual)->ppn = cpu_to_le32(0);
> +             (++desc_virtual)->ppn = DMA_PAGE_INVALID;
>               desc_virtual->num_pages = cpu_to_le32(0);
> +             kunmap_atomic(page_virtual);
>       }
>  
> -     if (likely(page_virtual != NULL))
> +     desc_dma = 0;
> +     list_for_each_entry_reverse(page, desc_pages, lru) {
> +             page_virtual = kmap_atomic(page);
> +             page_virtual[desc_per_page].ppn = desc_dma >> PAGE_SHIFT;
>               kunmap_atomic(page_virtual);
> +             desc_dma = dma_map_page(dev, page, 0, PAGE_SIZE,
> +                                     DMA_TO_DEVICE);
> +
> +             if (unlikely(dma_mapping_error(dev, desc_dma)))
> +                     goto out_err;
> +     }
> +     *first_dma = desc_dma;
>  
>       return 0;
>  out_err:
> -     list_for_each_entry_safe(page, next, desc_pages, lru) {
> -             list_del_init(&page->lru);
> -             __free_page(page);
> -     }
> +     vmw_gmr_free_descriptors(dev, DMA_ADDR_INVALID, desc_pages);
>       return ret;
>  }
>  
> -static inline void vmw_gmr_free_descriptors(struct list_head *desc_pages)
> -{
> -     struct page *page, *next;
> -
> -     list_for_each_entry_safe(page, next, desc_pages, lru) {
> -             list_del_init(&page->lru);
> -             __free_page(page);
> -     }
> -}
> -
>  static void vmw_gmr_fire_descriptors(struct vmw_private *dev_priv,
> -                                  int gmr_id, struct list_head *desc_pages)
> +                                  int gmr_id, dma_addr_t desc_dma)
>  {
> -     struct page *page;
> -
> -     if (unlikely(list_empty(desc_pages)))
> -             return;
> -
> -     page = list_entry(desc_pages->next, struct page, lru);
> -
>       mutex_lock(&dev_priv->hw_mutex);
>  
>       vmw_write(dev_priv, SVGA_REG_GMR_ID, gmr_id);
>       wmb();
> -     vmw_write(dev_priv, SVGA_REG_GMR_DESCRIPTOR, page_to_pfn(page));
> +     vmw_write(dev_priv, SVGA_REG_GMR_DESCRIPTOR, desc_dma >> PAGE_SHIFT);
>       mb();
>  
>       mutex_unlock(&dev_priv->hw_mutex);
>  
>  }
>  
> -/**
> - * FIXME: Adjust to the ttm lowmem / highmem storage to minimize
> - * the number of used descriptors.
> - */
> -
> -static unsigned long vmw_gmr_count_descriptors(struct page *pages[],
> -                                     unsigned long num_pages)
> -{
> -     unsigned long prev_pfn = ~(0UL);
> -     unsigned long pfn;
> -     unsigned long descriptors = 0;
> -
> -     while (num_pages--) {
> -             pfn = page_to_pfn(*pages++);
> -             if (prev_pfn + 1 != pfn)
> -                     ++descriptors;
> -             prev_pfn = pfn;
> -     }
> -
> -     return descriptors;
> -}
> -
>  int vmw_gmr_bind(struct vmw_private *dev_priv,
> -              struct page *pages[],
> +              const struct vmw_sg_table *vsgt,
>                unsigned long num_pages,
>                int gmr_id)
>  {
>       struct list_head desc_pages;
> +     dma_addr_t desc_dma = 0;
> +     struct device *dev = dev_priv->dev->dev;
> +     struct vmw_piter data_iter;
>       int ret;
>  
> +     vmw_piter_start(&data_iter, vsgt, 0);
> +
> +     if (unlikely(!vmw_piter_next(&data_iter)))
> +             return 0;
> +
>       if (likely(dev_priv->capabilities & SVGA_CAP_GMR2))
> -             return vmw_gmr2_bind(dev_priv, pages, num_pages, gmr_id);
> +             return vmw_gmr2_bind(dev_priv, &data_iter, num_pages, gmr_id);
>  
>       if (unlikely(!(dev_priv->capabilities & SVGA_CAP_GMR)))
>               return -EINVAL;
>  
> -     if (vmw_gmr_count_descriptors(pages, num_pages) >
> -         dev_priv->max_gmr_descriptors)
> +     if (vsgt->num_regions > dev_priv->max_gmr_descriptors)
>               return -EINVAL;
>  
>       INIT_LIST_HEAD(&desc_pages);
>  
> -     ret = vmw_gmr_build_descriptors(&desc_pages, pages, num_pages);
> +     ret = vmw_gmr_build_descriptors(dev, &desc_pages, &data_iter,
> +                                     num_pages, &desc_dma);
>       if (unlikely(ret != 0))
>               return ret;
>  
> -     vmw_gmr_fire_descriptors(dev_priv, gmr_id, &desc_pages);
> -     vmw_gmr_free_descriptors(&desc_pages);
> +     vmw_gmr_fire_descriptors(dev_priv, gmr_id, desc_dma);
> +     vmw_gmr_free_descriptors(dev, desc_dma, &desc_pages);
>  
>       return 0;
>  }
> -- 
> 1.7.10.4

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