[PATCH v3 2/6] drm/i915: Add support for asynchronous moving fence waiting
Matthew Auld
matthew.auld at intel.com
Mon Nov 15 13:13:09 UTC 2021
On 15/11/2021 12:42, Thomas Hellström wrote:
>
> On 11/15/21 13:36, Matthew Auld wrote:
>> On 14/11/2021 11:12, Thomas Hellström wrote:
>>> From: Maarten Lankhorst <maarten.lankhorst at linux.intel.com>
>>>
>>> For now, we will only allow async migration when TTM is used,
>>> so the paths we care about are related to TTM.
>>>
>>> The mmap path is handled by having the fence in ttm_bo->moving,
>>> when pinning, the binding only becomes available after the moving
>>> fence is signaled, and pinning a cpu map will only work after
>>> the moving fence signals.
>>>
>>> This should close all holes where userspace can read a buffer
>>> before it's fully migrated.
>>>
>>> v2:
>>> - Fix a couple of SPARSE warnings
>>> v3:
>>> - Fix a NULL pointer dereference
>>>
>>> Co-developed-by: Thomas Hellström <thomas.hellstrom at linux.intel.com>
>>> Signed-off-by: Thomas Hellström <thomas.hellstrom at linux.intel.com>
>>> Signed-off-by: Maarten Lankhorst <maarten.lankhorst at linux.intel.com>
>>> ---
>>> drivers/gpu/drm/i915/display/intel_fbdev.c | 7 ++--
>>> drivers/gpu/drm/i915/display/intel_overlay.c | 2 +-
>>> drivers/gpu/drm/i915/gem/i915_gem_pages.c | 6 +++
>>> .../i915/gem/selftests/i915_gem_coherency.c | 4 +-
>>> .../drm/i915/gem/selftests/i915_gem_mman.c | 22 ++++++-----
>>> drivers/gpu/drm/i915/i915_vma.c | 39 ++++++++++++++++++-
>>> drivers/gpu/drm/i915/i915_vma.h | 3 ++
>>> drivers/gpu/drm/i915/selftests/i915_vma.c | 4 +-
>>> 8 files changed, 69 insertions(+), 18 deletions(-)
>>>
>>> diff --git a/drivers/gpu/drm/i915/display/intel_fbdev.c
>>> b/drivers/gpu/drm/i915/display/intel_fbdev.c
>>> index adc3a81be9f7..5902ad0c2bd8 100644
>>> --- a/drivers/gpu/drm/i915/display/intel_fbdev.c
>>> +++ b/drivers/gpu/drm/i915/display/intel_fbdev.c
>>> @@ -265,11 +265,12 @@ static int intelfb_create(struct drm_fb_helper
>>> *helper,
>>> info->fix.smem_len = vma->node.size;
>>> }
>>> - vaddr = i915_vma_pin_iomap(vma);
>>> + vaddr = i915_vma_pin_iomap_unlocked(vma);
>>> if (IS_ERR(vaddr)) {
>>> - drm_err(&dev_priv->drm,
>>> - "Failed to remap framebuffer into virtual memory\n");
>>> ret = PTR_ERR(vaddr);
>>> + if (ret != -EINTR && ret != -ERESTARTSYS)
>>> + drm_err(&dev_priv->drm,
>>> + "Failed to remap framebuffer into virtual memory\n");
>>> goto out_unpin;
>>> }
>>> info->screen_base = vaddr;
>>> diff --git a/drivers/gpu/drm/i915/display/intel_overlay.c
>>> b/drivers/gpu/drm/i915/display/intel_overlay.c
>>> index 7e3f5c6ca484..21593f3f2664 100644
>>> --- a/drivers/gpu/drm/i915/display/intel_overlay.c
>>> +++ b/drivers/gpu/drm/i915/display/intel_overlay.c
>>> @@ -1357,7 +1357,7 @@ static int get_registers(struct intel_overlay
>>> *overlay, bool use_phys)
>>> overlay->flip_addr = sg_dma_address(obj->mm.pages->sgl);
>>> else
>>> overlay->flip_addr = i915_ggtt_offset(vma);
>>> - overlay->regs = i915_vma_pin_iomap(vma);
>>> + overlay->regs = i915_vma_pin_iomap_unlocked(vma);
>>> i915_vma_unpin(vma);
>>> if (IS_ERR(overlay->regs)) {
>>> diff --git a/drivers/gpu/drm/i915/gem/i915_gem_pages.c
>>> b/drivers/gpu/drm/i915/gem/i915_gem_pages.c
>>> index c4f684b7cc51..49c6e55c68ce 100644
>>> --- a/drivers/gpu/drm/i915/gem/i915_gem_pages.c
>>> +++ b/drivers/gpu/drm/i915/gem/i915_gem_pages.c
>>> @@ -418,6 +418,12 @@ void *i915_gem_object_pin_map(struct
>>> drm_i915_gem_object *obj,
>>> }
>>> if (!ptr) {
>>> + err = i915_gem_object_wait_moving_fence(obj, true);
>>> + if (err) {
>>> + ptr = ERR_PTR(err);
>>> + goto err_unpin;
>>> + }
>>> +
>>> if (GEM_WARN_ON(type == I915_MAP_WC &&
>>> !static_cpu_has(X86_FEATURE_PAT)))
>>> ptr = ERR_PTR(-ENODEV);
>>> diff --git a/drivers/gpu/drm/i915/gem/selftests/i915_gem_coherency.c
>>> b/drivers/gpu/drm/i915/gem/selftests/i915_gem_coherency.c
>>> index 13b088cc787e..067c512961ba 100644
>>> --- a/drivers/gpu/drm/i915/gem/selftests/i915_gem_coherency.c
>>> +++ b/drivers/gpu/drm/i915/gem/selftests/i915_gem_coherency.c
>>> @@ -101,7 +101,7 @@ static int gtt_set(struct context *ctx, unsigned
>>> long offset, u32 v)
>>> intel_gt_pm_get(vma->vm->gt);
>>> - map = i915_vma_pin_iomap(vma);
>>> + map = i915_vma_pin_iomap_unlocked(vma);
>>> i915_vma_unpin(vma);
>>> if (IS_ERR(map)) {
>>> err = PTR_ERR(map);
>>> @@ -134,7 +134,7 @@ static int gtt_get(struct context *ctx, unsigned
>>> long offset, u32 *v)
>>> intel_gt_pm_get(vma->vm->gt);
>>> - map = i915_vma_pin_iomap(vma);
>>> + map = i915_vma_pin_iomap_unlocked(vma);
>>> i915_vma_unpin(vma);
>>> if (IS_ERR(map)) {
>>> err = PTR_ERR(map);
>>> diff --git a/drivers/gpu/drm/i915/gem/selftests/i915_gem_mman.c
>>> b/drivers/gpu/drm/i915/gem/selftests/i915_gem_mman.c
>>> index 6d30cdfa80f3..5d54181c2145 100644
>>> --- a/drivers/gpu/drm/i915/gem/selftests/i915_gem_mman.c
>>> +++ b/drivers/gpu/drm/i915/gem/selftests/i915_gem_mman.c
>>> @@ -125,12 +125,13 @@ static int check_partial_mapping(struct
>>> drm_i915_gem_object *obj,
>>> n = page - view.partial.offset;
>>> GEM_BUG_ON(n >= view.partial.size);
>>> - io = i915_vma_pin_iomap(vma);
>>> + io = i915_vma_pin_iomap_unlocked(vma);
>>> i915_vma_unpin(vma);
>>> if (IS_ERR(io)) {
>>> - pr_err("Failed to iomap partial view: offset=%lu; err=%d\n",
>>> - page, (int)PTR_ERR(io));
>>> err = PTR_ERR(io);
>>> + if (err != -EINTR && err != -ERESTARTSYS)
>>> + pr_err("Failed to iomap partial view: offset=%lu;
>>> err=%d\n",
>>> + page, err);
>>> goto out;
>>> }
>>> @@ -219,12 +220,15 @@ static int check_partial_mappings(struct
>>> drm_i915_gem_object *obj,
>>> n = page - view.partial.offset;
>>> GEM_BUG_ON(n >= view.partial.size);
>>> - io = i915_vma_pin_iomap(vma);
>>> + io = i915_vma_pin_iomap_unlocked(vma);
>>> i915_vma_unpin(vma);
>>> if (IS_ERR(io)) {
>>> - pr_err("Failed to iomap partial view: offset=%lu;
>>> err=%d\n",
>>> - page, (int)PTR_ERR(io));
>>> - return PTR_ERR(io);
>>> + int err = PTR_ERR(io);
>>> +
>>> + if (err != -EINTR && err != -ERESTARTSYS)
>>> + pr_err("Failed to iomap partial view: offset=%lu;
>>> err=%d\n",
>>> + page, err);
>>> + return err;
>>> }
>>> iowrite32(page, io + n * PAGE_SIZE / sizeof(*io));
>>> @@ -773,7 +777,7 @@ static int gtt_set(struct drm_i915_gem_object *obj)
>>> return PTR_ERR(vma);
>>> intel_gt_pm_get(vma->vm->gt);
>>> - map = i915_vma_pin_iomap(vma);
>>> + map = i915_vma_pin_iomap_unlocked(vma);
>>> i915_vma_unpin(vma);
>>> if (IS_ERR(map)) {
>>> err = PTR_ERR(map);
>>> @@ -799,7 +803,7 @@ static int gtt_check(struct drm_i915_gem_object
>>> *obj)
>>> return PTR_ERR(vma);
>>> intel_gt_pm_get(vma->vm->gt);
>>> - map = i915_vma_pin_iomap(vma);
>>> + map = i915_vma_pin_iomap_unlocked(vma);
>>> i915_vma_unpin(vma);
>>> if (IS_ERR(map)) {
>>> err = PTR_ERR(map);
>>> diff --git a/drivers/gpu/drm/i915/i915_vma.c
>>> b/drivers/gpu/drm/i915/i915_vma.c
>>> index 8781c4f61952..069f22b3cd48 100644
>>> --- a/drivers/gpu/drm/i915/i915_vma.c
>>> +++ b/drivers/gpu/drm/i915/i915_vma.c
>>> @@ -431,6 +431,13 @@ int i915_vma_bind(struct i915_vma *vma,
>>> work->pinned = i915_gem_object_get(vma->obj);
>>> }
>>> } else {
>>> + if (vma->obj) {
>>> + int ret;
>>> +
>>> + ret = i915_gem_object_wait_moving_fence(vma->obj, true);
>>> + if (ret)
>>> + return ret;
>>> + }
>>> vma->ops->bind_vma(vma->vm, NULL, vma, cache_level,
>>> bind_flags);
>>> }
>>> @@ -455,6 +462,10 @@ void __iomem *i915_vma_pin_iomap(struct
>>> i915_vma *vma)
>>> ptr = READ_ONCE(vma->iomap);
>>> if (ptr == NULL) {
>>> + err = i915_gem_object_wait_moving_fence(vma->obj, true);
>>> + if (err)
>>> + goto err;
>>> +
>>> /*
>>> * TODO: consider just using i915_gem_object_pin_map() for
>>> lmem
>>> * instead, which already supports mapping non-contiguous
>>> chunks
>>> @@ -496,6 +507,25 @@ void __iomem *i915_vma_pin_iomap(struct i915_vma
>>> *vma)
>>> return IO_ERR_PTR(err);
>>> }
>>> +void __iomem *i915_vma_pin_iomap_unlocked(struct i915_vma *vma)
>>> +{
>>> + struct i915_gem_ww_ctx ww;
>>> + void __iomem *map;
>>> + int err;
>>> +
>>> + for_i915_gem_ww(&ww, err, true) {
>>> + err = i915_gem_object_lock(vma->obj, &ww);
>>> + if (err)
>>> + continue;
>>> +
>>> + map = i915_vma_pin_iomap(vma);
>>> + }
>>> + if (err)
>>> + map = IO_ERR_PTR(err);
>>> +
>>> + return map;
>>> +}
>>
>> What is the reason for this change? Is this strictly related to this
>> series/commit?
>
> Yes, it's because pulling out the moving fence requires the dma_resv lock.
Ok, I was thinking that vma_pin_iomap is only ever called on an already
bound GGTT vma, for which we do a syncronous wait_for_bind, but maybe
that's not always true?
Reviewed-by: Matthew Auld <matthew.auld at intel.com>
>
> /Thomas
>
>
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