From 23c18c71da801fb7ce11acc3041e4f10a1bb5cb0 Mon Sep 17 00:00:00 2001 From: Daniel Vetter Date: Sun, 25 Mar 2012 19:47:42 +0200 Subject: [PATCH] drm/i915: fixup in-line clflushing on bit17 swizzled bos The issue is that with inline clflushing the clflushing isn't properly swizzled. Fix this by - always clflushing entire 128 byte chunks and - unconditionally flush before writes when swizzling a given page. We could be clever and check whether we pwrite a partial 128 byte chunk instead of a partial cacheline, but I've figured that's not worth it. Now the usual approach is to fold this into the original patch series, but I've opted against this because - this fixes a corner case only very old userspace relies on and - I'd like to not invalidate all the testing the pwrite rewrite has gotten. This fixes the regression notice by tests/gem_tiled_partial_prite_pread from i-g-t. Unfortunately it doesn't fix the issues with partial pwrites to tiled buffers on bit17 swizzling machines. But that is also broken without the pwrite patches, so likely a different issue (or a problem with the testcase). v2: Simplify the patch by dropping the overly clever partial write logic for swizzled pages. Reviewed-by: Chris Wilson Signed-Off-by: Daniel Vetter --- drivers/gpu/drm/i915/i915_gem.c | 39 +++++++++++++++++++++++++++------ 1 file changed, 32 insertions(+), 7 deletions(-) diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c index 6dc832902f5..c964dfbdb57 100644 --- a/drivers/gpu/drm/i915/i915_gem.c +++ b/drivers/gpu/drm/i915/i915_gem.c @@ -313,6 +313,28 @@ shmem_pread_fast(struct page *page, int shmem_page_offset, int page_length, return ret; } +static void +shmem_clflush_swizzled_range(char *addr, unsigned long length, + bool swizzled) +{ + if (swizzled) { + unsigned long start = (unsigned long) addr; + unsigned long end = (unsigned long) addr + length; + + /* For swizzling simply ensure that we always flush both + * channels. Lame, but simple and it works. Swizzled + * pwrite/pread is far from a hotpath - current userspace + * doesn't use it at all. */ + start = round_down(start, 128); + end = round_up(end, 128); + + drm_clflush_virt_range((void *)start, end - start); + } else { + drm_clflush_virt_range(addr, length); + } + +} + /* Only difference to the fast-path function is that this can handle bit17 * and uses non-atomic copy and kmap functions. */ static int @@ -325,8 +347,9 @@ shmem_pread_slow(struct page *page, int shmem_page_offset, int page_length, vaddr = kmap(page); if (needs_clflush) - drm_clflush_virt_range(vaddr + shmem_page_offset, - page_length); + shmem_clflush_swizzled_range(vaddr + shmem_page_offset, + page_length, + page_do_bit17_swizzling); if (page_do_bit17_swizzling) ret = __copy_to_user_swizzled(user_data, @@ -637,9 +660,10 @@ shmem_pwrite_slow(struct page *page, int shmem_page_offset, int page_length, int ret; vaddr = kmap(page); - if (needs_clflush_before) - drm_clflush_virt_range(vaddr + shmem_page_offset, - page_length); + if (needs_clflush_before || page_do_bit17_swizzling) + shmem_clflush_swizzled_range(vaddr + shmem_page_offset, + page_length, + page_do_bit17_swizzling); if (page_do_bit17_swizzling) ret = __copy_from_user_swizzled(vaddr, shmem_page_offset, user_data, @@ -649,8 +673,9 @@ shmem_pwrite_slow(struct page *page, int shmem_page_offset, int page_length, user_data, page_length); if (needs_clflush_after) - drm_clflush_virt_range(vaddr + shmem_page_offset, - page_length); + shmem_clflush_swizzled_range(vaddr + shmem_page_offset, + page_length, + page_do_bit17_swizzling); kunmap(page); return ret; -- 2.41.0