2022-07-27 12:45:40

by Mauro Carvalho Chehab

[permalink] [raw]
Subject: [PATCH v3 6/6] drm/i915/gt: describe the new tlb parameter at i915_vma_resource

TLB cache invalidation can happen on two different situations:

1. synchronously, at __vma_put_pages();
2. asynchronously.

On the first case, TLB cache invalidation happens inside
__vma_put_pages(). So, no need to do it later on.

However, on the second case, the pages will keep in memory
until __i915_vma_evict() is called.

So, we need to store the TLB data at struct i915_vma_resource,
in order to do a TLB cache invalidation before allowing
userspace to re-use the same memory.

So, i915_vma_resource_unbind() has gained a new parameter
in order to store the TLB data at the second case.

Document it.

Signed-off-by: Mauro Carvalho Chehab <[email protected]>
---

To avoid mailbombing on a large number of people, only mailing lists were C/C on the cover.
See [PATCH v3 0/6] at: https://lore.kernel.org/all/[email protected]/

drivers/gpu/drm/i915/i915_vma_resource.c | 4 ++++
1 file changed, 4 insertions(+)

diff --git a/drivers/gpu/drm/i915/i915_vma_resource.c b/drivers/gpu/drm/i915/i915_vma_resource.c
index 5a67995ea5fe..4fe09ea0a825 100644
--- a/drivers/gpu/drm/i915/i915_vma_resource.c
+++ b/drivers/gpu/drm/i915/i915_vma_resource.c
@@ -216,6 +216,10 @@ i915_vma_resource_fence_notify(struct i915_sw_fence *fence,
/**
* i915_vma_resource_unbind - Unbind a vma resource
* @vma_res: The vma resource to unbind.
+ * @tlb: pointer to vma->obj->mm.tlb associated with the resource
+ * to be stored at vma_res->tlb. When not-NULL, it will be used
+ * to do TLB cache invalidation before freeing a VMA resource.
+ * used only for async unbind.
*
* At this point this function does little more than publish a fence that
* signals immediately unless signaling is held back.
--
2.36.1


2022-07-27 15:12:32

by Andi Shyti

[permalink] [raw]
Subject: Re: [Intel-gfx] [PATCH v3 6/6] drm/i915/gt: describe the new tlb parameter at i915_vma_resource

Hi Mauro,

> TLB cache invalidation can happen on two different situations:
>
> 1. synchronously, at __vma_put_pages();
> 2. asynchronously.
>
> On the first case, TLB cache invalidation happens inside
> __vma_put_pages(). So, no need to do it later on.
>
> However, on the second case, the pages will keep in memory
> until __i915_vma_evict() is called.
>
> So, we need to store the TLB data at struct i915_vma_resource,
> in order to do a TLB cache invalidation before allowing
> userspace to re-use the same memory.
>
> So, i915_vma_resource_unbind() has gained a new parameter
> in order to store the TLB data at the second case.
>
> Document it.
>
> Signed-off-by: Mauro Carvalho Chehab <[email protected]>
> ---
>
> To avoid mailbombing on a large number of people, only mailing lists were C/C on the cover.
> See [PATCH v3 0/6] at: https://lore.kernel.org/all/[email protected]/
>
> drivers/gpu/drm/i915/i915_vma_resource.c | 4 ++++
> 1 file changed, 4 insertions(+)
>
> diff --git a/drivers/gpu/drm/i915/i915_vma_resource.c b/drivers/gpu/drm/i915/i915_vma_resource.c
> index 5a67995ea5fe..4fe09ea0a825 100644
> --- a/drivers/gpu/drm/i915/i915_vma_resource.c
> +++ b/drivers/gpu/drm/i915/i915_vma_resource.c
> @@ -216,6 +216,10 @@ i915_vma_resource_fence_notify(struct i915_sw_fence *fence,
> /**
> * i915_vma_resource_unbind - Unbind a vma resource
> * @vma_res: The vma resource to unbind.
> + * @tlb: pointer to vma->obj->mm.tlb associated with the resource
> + * to be stored at vma_res->tlb. When not-NULL, it will be used
> + * to do TLB cache invalidation before freeing a VMA resource.
> + * used only for async unbind.

/used/Used/

With that:

Reviewed-by: Andi Shyti <[email protected]>

Thanks,
Andi