On Wed, 2014-02-12 at 14:28 -0800, Ben Widawsky wrote:
> Like cleanup in an earlier patch, the code becomes much more readable,
> and easier to extend if we extract out helper functions for the various
> stages of init.
>
> Note that with this patch it becomes really simple, and tempting to begin
> using the 'goto out' idiom with explicit free/fini semantics. I've
> kept the error path as similar as possible to the cleanup() function to
> make sure cleanup is as robust as possible
>
> v2: Remove comment "NB:From here on, ppgtt->base.cleanup() should
> function properly"
> Update commit message to reflect above
>
> Signed-off-by: Ben Widawsky <ben@xxxxxxxxxxxx>
> ---
> drivers/gpu/drm/i915/i915_gem_gtt.c | 182 +++++++++++++++++++++++++-----------
> 1 file changed, 126 insertions(+), 56 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/i915_gem_gtt.c b/drivers/gpu/drm/i915/i915_gem_gtt.c
> index c6c221c..8a5cad9 100644
> --- a/drivers/gpu/drm/i915/i915_gem_gtt.c
> +++ b/drivers/gpu/drm/i915/i915_gem_gtt.c
> @@ -366,91 +366,161 @@ static void gen8_ppgtt_cleanup(struct i915_address_space *vm)
> gen8_ppgtt_free(ppgtt);
> }
>
> -/**
> - * GEN8 legacy ppgtt programming is accomplished through a max 4 PDP registers
> - * with a net effect resembling a 2-level page table in normal x86 terms. Each
> - * PDP represents 1GB of memory 4 * 512 * 512 * 4096 = 4GB legacy 32b address
> - * space.
> - *
> - * FIXME: split allocation into smaller pieces. For now we only ever do this
> - * once, but with full PPGTT, the multiple contiguous allocations will be bad.
> - * TODO: Do something with the size parameter
> - */
> -static int gen8_ppgtt_init(struct i915_hw_ppgtt *ppgtt, uint64_t size)
> +static int gen8_ppgtt_allocate_page_tables(struct i915_hw_ppgtt *ppgtt,
> + const int max_pdp)
> {
> struct page *pt_pages;
> - const int max_pdp = DIV_ROUND_UP(size, 1 << 30);
> const int num_pt_pages = GEN8_PDES_PER_PAGE * max_pdp;
> - int i, j, ret;
> -
> - if (size % (1<<30))
> - DRM_INFO("Pages will be wasted unless GTT size (%llu) is divisible by 1GB\n", size);
> -
> - /* 1. Do all our allocations for page directories and page tables */
> - ppgtt->pd_pages = alloc_pages(GFP_KERNEL, get_order(max_pdp << PAGE_SHIFT));
> - if (!ppgtt->pd_pages)
> - return -ENOMEM;
>
> pt_pages = alloc_pages(GFP_KERNEL, get_order(num_pt_pages << PAGE_SHIFT));
> - if (!pt_pages) {
> - __free_pages(ppgtt->pd_pages, get_order(max_pdp << PAGE_SHIFT));
> + if (!pt_pages)
> return -ENOMEM;
> - }
>
> ppgtt->gen8_pt_pages = pt_pages;
> - ppgtt->num_pd_pages = 1 << get_order(max_pdp << PAGE_SHIFT);
> ppgtt->num_pt_pages = 1 << get_order(num_pt_pages << PAGE_SHIFT);
> - ppgtt->num_pd_entries = max_pdp * GEN8_PDES_PER_PAGE;
> - BUG_ON(ppgtt->num_pd_pages > GEN8_LEGACY_PDPS);
>
> - ppgtt->gen8_pt_dma_addr = kcalloc(max_pdp,
> + return 0;
> +}
> +
> +static int gen8_ppgtt_allocate_dma(struct i915_hw_ppgtt *ppgtt)
> +{
> + int i;
> +
> + ppgtt->gen8_pt_dma_addr = kcalloc(ppgtt->num_pd_entries,
> sizeof(*ppgtt->gen8_pt_dma_addr),
> GFP_KERNEL);
> - if (!ppgtt->gen8_pt_dma_addr) {
> - ret = -ENOMEM;
> - goto bail;
> - }
> + if (!ppgtt->gen8_pt_dma_addr)
> + return -ENOMEM;
>
> - for (i = 0; i < max_pdp; i++) {
> + for (i = 0; i < ppgtt->num_pd_entries; i++) {
> ppgtt->gen8_pt_dma_addr[i] = kcalloc(GEN8_PDES_PER_PAGE,
> sizeof(dma_addr_t),
> GFP_KERNEL);
> if (!ppgtt->gen8_pt_dma_addr[i]) {
> - ret = -ENOMEM;
> - goto bail;
> + kfree(ppgtt->gen8_pt_dma_addr);
> + while(i--)
> + kfree(ppgtt->gen8_pt_dma_addr[i]);
> +
> + return -ENOMEM;
> }
> }
>
> + return 0;
> +}
> +
> +static int gen8_ppgtt_allocate_page_directories(struct i915_hw_ppgtt *ppgtt,
> + const int max_pdp)
> +{
> + ppgtt->pd_pages = alloc_pages(GFP_KERNEL, get_order(max_pdp << PAGE_SHIFT));
> + if (!ppgtt->pd_pages)
> + return -ENOMEM;
> +
> + ppgtt->num_pd_pages = 1 << get_order(max_pdp << PAGE_SHIFT);
> +
> + return 0;
> +}
> +
> +static int gen8_ppgtt_alloc(struct i915_hw_ppgtt *ppgtt,
> + const int max_pdp)
> +{
> + int ret;
> +
> + ret = gen8_ppgtt_allocate_page_directories(ppgtt, max_pdp);
> + if (ret)
> + return ret;
> +
> + ret = gen8_ppgtt_allocate_page_tables(ppgtt, max_pdp);
> + if (ret) {
> + __free_pages(ppgtt->pd_pages, get_order(max_pdp << PAGE_SHIFT));
> + return ret;
> + }
> +
> + ppgtt->num_pd_entries = max_pdp * GEN8_PDES_PER_PAGE;
> + BUG_ON(ppgtt->num_pd_pages > GEN8_LEGACY_PDPS);
This check belongs to gen8_ppgtt_allocate_page_directories().
> +
> + ret = gen8_ppgtt_allocate_dma(ppgtt);
> + if (ret)
> + gen8_ppgtt_free(ppgtt);
Just for reference, this the same ppgtt->gen8_pt_dma_addr NULL deref
issue on the error path as in 2/9.
> +
> + return ret;
> +}
> +
> +static int gen8_ppgtt_setup_page_directories(struct i915_hw_ppgtt *ppgtt,
> + const int pd)
> +{
> + dma_addr_t pd_addr;
> + int ret;
> +
> + pd_addr = pci_map_page(ppgtt->base.dev->pdev,
> + &ppgtt->pd_pages[pd], 0,
> + PAGE_SIZE, PCI_DMA_BIDIRECTIONAL);
> +
> + ret = pci_dma_mapping_error(ppgtt->base.dev->pdev, pd_addr);
> + if (ret)
> + return ret;
> +
> + ppgtt->pd_dma_addr[pd] = pd_addr;
> +
> + return 0;
> +}
> +
> +static int gen8_ppgtt_setup_page_tables(struct i915_hw_ppgtt *ppgtt,
> + const int pd,
> + const int pt)
> +{
> + dma_addr_t pt_addr;
> + struct page *p;
> + int ret;
> +
> + p = &ppgtt->gen8_pt_pages[pd * GEN8_PDES_PER_PAGE + pt];
> + pt_addr = pci_map_page(ppgtt->base.dev->pdev,
> + p, 0, PAGE_SIZE, PCI_DMA_BIDIRECTIONAL);
> + ret = pci_dma_mapping_error(ppgtt->base.dev->pdev, pt_addr);
> + if (ret)
> + return ret;
> +
> + ppgtt->gen8_pt_dma_addr[pd][pt] = pt_addr;
> +
> + return 0;
> +}
> +
> +/**
> + * GEN8 legacy ppgtt programming is accomplished through a max 4 PDP registers
> + * with a net effect resembling a 2-level page table in normal x86 terms. Each
> + * PDP represents 1GB of memory 4 * 512 * 512 * 4096 = 4GB legacy 32b address
> + * space.
> + *
> + * FIXME: split allocation into smaller pieces. For now we only ever do this
> + * once, but with full PPGTT, the multiple contiguous allocations will be bad.
> + * TODO: Do something with the size parameter
> + */
> +static int gen8_ppgtt_init(struct i915_hw_ppgtt *ppgtt, uint64_t size)
> +{
> + const int max_pdp = DIV_ROUND_UP(size, 1 << 30);
> + const int min_pt_pages = GEN8_PDES_PER_PAGE * max_pdp;
> + int i, j, ret;
> +
> + if (size % (1<<30))
> + DRM_INFO("Pages will be wasted unless GTT size (%llu) is divisible by 1GB\n", size);
> +
> + /* 1. Do all our allocations for page directories and page tables. */
> + ret = gen8_ppgtt_alloc(ppgtt, max_pdp);
> + if (ret)
> + return ret;
> +
> /*
> - * 2. Create all the DMA mappings for the page directories and page
> - * tables
> + * 2. Create DMA mappings for the page directories and page tables.
> */
> for (i = 0; i < max_pdp; i++) {
> - dma_addr_t pd_addr, pt_addr;
> -
> - /* Get the page table mappings per page directory */
> for (j = 0; j < GEN8_PDES_PER_PAGE; j++) {
> - struct page *p = &pt_pages[i * GEN8_PDES_PER_PAGE + j];
> -
> - pt_addr = pci_map_page(ppgtt->base.dev->pdev,
> - p, 0, PAGE_SIZE,
> - PCI_DMA_BIDIRECTIONAL);
> - ret = pci_dma_mapping_error(ppgtt->base.dev->pdev, pt_addr);
> + ret = gen8_ppgtt_setup_page_tables(ppgtt, i, j);
> if (ret)
> goto bail;
> -
> - ppgtt->gen8_pt_dma_addr[i][j] = pt_addr;
> }
>
> - /* And the page directory mappings */
> - pd_addr = pci_map_page(ppgtt->base.dev->pdev,
> - &ppgtt->pd_pages[i], 0,
> - PAGE_SIZE, PCI_DMA_BIDIRECTIONAL);
> - ret = pci_dma_mapping_error(ppgtt->base.dev->pdev, pd_addr);
> + ret = gen8_ppgtt_setup_page_directories(ppgtt, i);
> if (ret)
> goto bail;
Again only for reference the same leaked mappings for page tables on the
error path as in 2/9.
> -
> - ppgtt->pd_dma_addr[i] = pd_addr;
> }
>
> /*
> @@ -488,7 +558,7 @@ static int gen8_ppgtt_init(struct i915_hw_ppgtt *ppgtt, uint64_t size)
> ppgtt->num_pd_pages, ppgtt->num_pd_pages - max_pdp);
> DRM_DEBUG_DRIVER("Allocated %d pages for page tables (%lld wasted)\n",
> ppgtt->num_pt_pages,
> - (ppgtt->num_pt_pages - num_pt_pages) +
> + (ppgtt->num_pt_pages - min_pt_pages) +
> size % (1<<30));
> return 0;
>
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