On 8 June 2018 at 13:55, Chris Wilson <chris@xxxxxxxxxxxxxxxxxx> wrote:
> As we were only supporting aliasing_ppgtt on gen7 for some time, we
> saved a few checks by preallocating the page directories on creation.
> However, since we need 2MiB of page directories for each ppgtt, to
> support arbitrary numbers of user contexts, we need to be more prudent
> in our allocations, and defer the page allocation until it is used. We
> don't recover unused pages yet as we found that doing so on the fly
> (i.e. altering TLB entries) would confuse the GPU.
>
> Signed-off-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
> Cc: Joonas Lahtinen <joonas.lahtinen@xxxxxxxxxxxxxxx>
> Cc: Mika Kuoppala <mika.kuoppala@xxxxxxxxxxxxxxx>
> Cc: Matthew Auld <matthew.william.auld@xxxxxxxxx>
> Reviewed-by: Matthew Auld <matthew.william.auld@xxxxxxxxx>
> ---
> drivers/gpu/drm/i915/i915_gem_gtt.c | 67 +++++++++++------------------
> 1 file changed, 26 insertions(+), 41 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/i915_gem_gtt.c b/drivers/gpu/drm/i915/i915_gem_gtt.c
> index d5af099939f6..e611884596a6 100644
> --- a/drivers/gpu/drm/i915/i915_gem_gtt.c
> +++ b/drivers/gpu/drm/i915/i915_gem_gtt.c
> @@ -190,11 +190,19 @@ int intel_sanitize_enable_ppgtt(struct drm_i915_private *dev_priv,
> return 1;
> }
>
> -static int gen6_ppgtt_bind_vma(struct i915_vma *vma,
> - enum i915_cache_level cache_level,
> - u32 unused)
> +static int ppgtt_bind_vma(struct i915_vma *vma,
> + enum i915_cache_level cache_level,
> + u32 unused)
> {
> u32 pte_flags;
> + int err;
> +
> + if (!(vma->flags & I915_VMA_LOCAL_BIND)) {
> + err = vma->vm->allocate_va_range(vma->vm,
> + vma->node.start, vma->size);
> + if (err)
> + return err;
> + }
>
> /* Currently applicable only to VLV */
> pte_flags = 0;
> @@ -206,22 +214,6 @@ static int gen6_ppgtt_bind_vma(struct i915_vma *vma,
> return 0;
> }
>
> -static int gen8_ppgtt_bind_vma(struct i915_vma *vma,
> - enum i915_cache_level cache_level,
> - u32 unused)
> -{
> - int ret;
> -
> - if (!(vma->flags & I915_VMA_LOCAL_BIND)) {
> - ret = vma->vm->allocate_va_range(vma->vm,
> - vma->node.start, vma->size);
> - if (ret)
> - return ret;
> - }
> -
> - return gen6_ppgtt_bind_vma(vma, cache_level, unused);
> -}
> -
> static void ppgtt_unbind_vma(struct i915_vma *vma)
> {
> vma->vm->clear_range(vma->vm, vma->node.start, vma->size);
> @@ -1622,7 +1614,7 @@ static struct i915_hw_ppgtt *gen8_ppgtt_create(struct drm_i915_private *i915)
> ppgtt->vm.cleanup = gen8_ppgtt_cleanup;
> ppgtt->debug_dump = gen8_dump_ppgtt;
>
> - ppgtt->vm.vma_ops.bind_vma = gen8_ppgtt_bind_vma;
> + ppgtt->vm.vma_ops.bind_vma = ppgtt_bind_vma;
> ppgtt->vm.vma_ops.unbind_vma = ppgtt_unbind_vma;
> ppgtt->vm.vma_ops.set_pages = ppgtt_set_pages;
> ppgtt->vm.vma_ops.clear_pages = clear_pages;
> @@ -1837,7 +1829,8 @@ static void gen6_ppgtt_clear_range(struct i915_address_space *vm,
>
> num_entries -= end - pte;
>
> - /* Note that the hw doesn't support removing PDE on the fly
> + /*
> + * Note that the hw doesn't support removing PDE on the fly
> * (they are cached inside the context with no means to
> * invalidate the cache), so we can only reset the PTE
> * entries back to scratch.
> @@ -2106,12 +2099,13 @@ static struct i915_hw_ppgtt *gen6_ppgtt_create(struct drm_i915_private *i915)
>
> ppgtt->base.vm.total = I915_PDES * GEN6_PTES * PAGE_SIZE;
>
> + ppgtt->base.vm.allocate_va_range = gen6_alloc_va_range;
Ah, in gen6_alloc_va_range() I think we now need:
unwind_out:
- gen6_ppgtt_clear_range(vm, from, start);
+ gen6_ppgtt_clear_range(vm, from, start - from);
return -ENOMEM;
}
?
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