[Intel-gfx] [PATCH] Revert "drm/vgem: fix cache synchronization on arm/arm64"
Daniel Vetter
daniel at ffwll.ch
Fri Aug 2 15:06:51 UTC 2019
On Fri, Aug 02, 2019 at 10:18:10AM -0400, Sean Paul wrote:
> On Thu, Aug 01, 2019 at 01:44:58PM +0100, Chris Wilson wrote:
> > commit 7e9e5ead55be ("drm/vgem: fix cache synchronization on arm/arm64")
> > broke all of the !llc i915-vgem coherency tests in CI, and left the HW
> > very, very unhappy (which is even more scary).
> >
> > Fixes: 7e9e5ead55be ("drm/vgem: fix cache synchronization on arm/arm64")
> > Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
>
> Acked-by: Sean Paul <sean at poorly.run>
Applied to drm-fixes directly.
Thanks, Daniel
>
> > Cc: Daniel Vetter <daniel.vetter at ffwll.ch>
> > Cc: Rob Clark <robdclark at chromium.org>
> > Cc: Sean Paul <seanpaul at chromium.org>
> > ---
> > drivers/gpu/drm/vgem/vgem_drv.c | 130 ++++++++++++--------------------
> > 1 file changed, 47 insertions(+), 83 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/vgem/vgem_drv.c b/drivers/gpu/drm/vgem/vgem_drv.c
> > index b98689fb0d5d..5bd60ded3d81 100644
> > --- a/drivers/gpu/drm/vgem/vgem_drv.c
> > +++ b/drivers/gpu/drm/vgem/vgem_drv.c
> > @@ -54,16 +54,10 @@ static struct vgem_device {
> > struct platform_device *platform;
> > } *vgem_device;
> >
> > -static void sync_and_unpin(struct drm_vgem_gem_object *bo);
> > -static struct page **pin_and_sync(struct drm_vgem_gem_object *bo);
> > -
> > static void vgem_gem_free_object(struct drm_gem_object *obj)
> > {
> > struct drm_vgem_gem_object *vgem_obj = to_vgem_bo(obj);
> >
> > - if (!obj->import_attach)
> > - sync_and_unpin(vgem_obj);
> > -
> > kvfree(vgem_obj->pages);
> > mutex_destroy(&vgem_obj->pages_lock);
> >
> > @@ -91,15 +85,40 @@ static vm_fault_t vgem_gem_fault(struct vm_fault *vmf)
> > return VM_FAULT_SIGBUS;
> >
> > mutex_lock(&obj->pages_lock);
> > - if (!obj->pages)
> > - pin_and_sync(obj);
> > if (obj->pages) {
> > get_page(obj->pages[page_offset]);
> > vmf->page = obj->pages[page_offset];
> > ret = 0;
> > }
> > mutex_unlock(&obj->pages_lock);
> > + if (ret) {
> > + struct page *page;
> > +
> > + page = shmem_read_mapping_page(
> > + file_inode(obj->base.filp)->i_mapping,
> > + page_offset);
> > + if (!IS_ERR(page)) {
> > + vmf->page = page;
> > + ret = 0;
> > + } else switch (PTR_ERR(page)) {
> > + case -ENOSPC:
> > + case -ENOMEM:
> > + ret = VM_FAULT_OOM;
> > + break;
> > + case -EBUSY:
> > + ret = VM_FAULT_RETRY;
> > + break;
> > + case -EFAULT:
> > + case -EINVAL:
> > + ret = VM_FAULT_SIGBUS;
> > + break;
> > + default:
> > + WARN_ON(PTR_ERR(page));
> > + ret = VM_FAULT_SIGBUS;
> > + break;
> > + }
> >
> > + }
> > return ret;
> > }
> >
> > @@ -265,93 +284,32 @@ static const struct file_operations vgem_driver_fops = {
> > .release = drm_release,
> > };
> >
> > -/* Called under pages_lock, except in free path (where it can't race): */
> > -static void sync_and_unpin(struct drm_vgem_gem_object *bo)
> > -{
> > - struct drm_device *dev = bo->base.dev;
> > -
> > - if (bo->table) {
> > - dma_sync_sg_for_cpu(dev->dev, bo->table->sgl,
> > - bo->table->nents, DMA_BIDIRECTIONAL);
> > - sg_free_table(bo->table);
> > - kfree(bo->table);
> > - bo->table = NULL;
> > - }
> > -
> > - if (bo->pages) {
> > - drm_gem_put_pages(&bo->base, bo->pages, true, true);
> > - bo->pages = NULL;
> > - }
> > -}
> > -
> > -static struct page **pin_and_sync(struct drm_vgem_gem_object *bo)
> > -{
> > - struct drm_device *dev = bo->base.dev;
> > - int npages = bo->base.size >> PAGE_SHIFT;
> > - struct page **pages;
> > - struct sg_table *sgt;
> > -
> > - WARN_ON(!mutex_is_locked(&bo->pages_lock));
> > -
> > - pages = drm_gem_get_pages(&bo->base);
> > - if (IS_ERR(pages)) {
> > - bo->pages_pin_count--;
> > - mutex_unlock(&bo->pages_lock);
> > - return pages;
> > - }
> > -
> > - sgt = drm_prime_pages_to_sg(pages, npages);
> > - if (IS_ERR(sgt)) {
> > - dev_err(dev->dev,
> > - "failed to allocate sgt: %ld\n",
> > - PTR_ERR(bo->table));
> > - drm_gem_put_pages(&bo->base, pages, false, false);
> > - mutex_unlock(&bo->pages_lock);
> > - return ERR_CAST(bo->table);
> > - }
> > -
> > - /*
> > - * Flush the object from the CPU cache so that importers
> > - * can rely on coherent indirect access via the exported
> > - * dma-address.
> > - */
> > - dma_sync_sg_for_device(dev->dev, sgt->sgl,
> > - sgt->nents, DMA_BIDIRECTIONAL);
> > -
> > - bo->pages = pages;
> > - bo->table = sgt;
> > -
> > - return pages;
> > -}
> > -
> > static struct page **vgem_pin_pages(struct drm_vgem_gem_object *bo)
> > {
> > - struct page **pages;
> > -
> > mutex_lock(&bo->pages_lock);
> > - if (bo->pages_pin_count++ == 0 && !bo->pages) {
> > - pages = pin_and_sync(bo);
> > - } else {
> > - WARN_ON(!bo->pages);
> > - pages = bo->pages;
> > + if (bo->pages_pin_count++ == 0) {
> > + struct page **pages;
> > +
> > + pages = drm_gem_get_pages(&bo->base);
> > + if (IS_ERR(pages)) {
> > + bo->pages_pin_count--;
> > + mutex_unlock(&bo->pages_lock);
> > + return pages;
> > + }
> > +
> > + bo->pages = pages;
> > }
> > mutex_unlock(&bo->pages_lock);
> >
> > - return pages;
> > + return bo->pages;
> > }
> >
> > static void vgem_unpin_pages(struct drm_vgem_gem_object *bo)
> > {
> > - /*
> > - * We shouldn't hit this for imported bo's.. in the import
> > - * case we don't own the scatter-table
> > - */
> > - WARN_ON(bo->base.import_attach);
> > -
> > mutex_lock(&bo->pages_lock);
> > if (--bo->pages_pin_count == 0) {
> > - WARN_ON(!bo->table);
> > - sync_and_unpin(bo);
> > + drm_gem_put_pages(&bo->base, bo->pages, true, true);
> > + bo->pages = NULL;
> > }
> > mutex_unlock(&bo->pages_lock);
> > }
> > @@ -359,12 +317,18 @@ static void vgem_unpin_pages(struct drm_vgem_gem_object *bo)
> > static int vgem_prime_pin(struct drm_gem_object *obj)
> > {
> > struct drm_vgem_gem_object *bo = to_vgem_bo(obj);
> > + long n_pages = obj->size >> PAGE_SHIFT;
> > struct page **pages;
> >
> > pages = vgem_pin_pages(bo);
> > if (IS_ERR(pages))
> > return PTR_ERR(pages);
> >
> > + /* Flush the object from the CPU cache so that importers can rely
> > + * on coherent indirect access via the exported dma-address.
> > + */
> > + drm_clflush_pages(pages, n_pages);
> > +
> > return 0;
> > }
> >
> > --
> > 2.23.0.rc0
> >
> > _______________________________________________
> > Intel-gfx mailing list
> > Intel-gfx at lists.freedesktop.org
> > https://lists.freedesktop.org/mailman/listinfo/intel-gfx
>
> --
> Sean Paul, Software Engineer, Google / Chromium OS
--
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
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