Re: [PATCH 1/1] powerpc/kernel/iommu: Use largepool as a last resort when !largealloc
On Thu, 18 Mar 2021 14:44:17 -0300, Leonardo Bras wrote: > As of today, doing iommu_range_alloc() only for !largealloc (npages <= 15) > will only be able to use 3/4 of the available pages, given pages on > largepool not being available for !largealloc. > > This could mean some drivers not being able to fully use all the available > pages for the DMA window. > > [...] Applied to powerpc/next. [1/1] powerpc/kernel/iommu: Use largepool as a last resort when !largealloc https://git.kernel.org/powerpc/c/fc5590fd56c9608f317729b59a56dad2a75d633f cheers
Re: [PATCH 1/1] powerpc/kernel/iommu: Use largepool as a last resort when !largealloc
Hello,
FYI: This patch was reviewed when it was part of another patchset:
http://patchwork.ozlabs.org/project/linuxppc-dev/patch/20200817234033.442511-4-leobra...@gmail.com/
On Thu, 2021-03-18 at 14:44 -0300, Leonardo Bras wrote:
> As of today, doing iommu_range_alloc() only for !largealloc (npages <= 15)
> will only be able to use 3/4 of the available pages, given pages on
> largepool not being available for !largealloc.
>
> This could mean some drivers not being able to fully use all the available
> pages for the DMA window.
>
> Add pages on largepool as a last resort for !largealloc, making all pages
> of the DMA window available.
>
> Signed-off-by: Leonardo Bras
> Reviewed-by: Alexey Kardashevskiy
> ---
> arch/powerpc/kernel/iommu.c | 9 +
> 1 file changed, 9 insertions(+)
>
> diff --git a/arch/powerpc/kernel/iommu.c b/arch/powerpc/kernel/iommu.c
> index 3329ef045805..ae6ad8dca605 100644
> --- a/arch/powerpc/kernel/iommu.c
> +++ b/arch/powerpc/kernel/iommu.c
> @@ -255,6 +255,15 @@ static unsigned long iommu_range_alloc(struct device
> *dev,
> pass++;
> goto again;
>
>
> + } else if (pass == tbl->nr_pools + 1) {
> + /* Last resort: try largepool */
> + spin_unlock(>lock);
> + pool = >large_pool;
> + spin_lock(>lock);
> + pool->hint = pool->start;
> + pass++;
> + goto again;
> +
> } else {
> /* Give up */
> spin_unlock_irqrestore(&(pool->lock), flags);
[PATCH 1/1] powerpc/kernel/iommu: Use largepool as a last resort when !largealloc
As of today, doing iommu_range_alloc() only for !largealloc (npages <= 15)
will only be able to use 3/4 of the available pages, given pages on
largepool not being available for !largealloc.
This could mean some drivers not being able to fully use all the available
pages for the DMA window.
Add pages on largepool as a last resort for !largealloc, making all pages
of the DMA window available.
Signed-off-by: Leonardo Bras
Reviewed-by: Alexey Kardashevskiy
---
arch/powerpc/kernel/iommu.c | 9 +
1 file changed, 9 insertions(+)
diff --git a/arch/powerpc/kernel/iommu.c b/arch/powerpc/kernel/iommu.c
index 3329ef045805..ae6ad8dca605 100644
--- a/arch/powerpc/kernel/iommu.c
+++ b/arch/powerpc/kernel/iommu.c
@@ -255,6 +255,15 @@ static unsigned long iommu_range_alloc(struct device *dev,
pass++;
goto again;
+ } else if (pass == tbl->nr_pools + 1) {
+ /* Last resort: try largepool */
+ spin_unlock(>lock);
+ pool = >large_pool;
+ spin_lock(>lock);
+ pool->hint = pool->start;
+ pass++;
+ goto again;
+
} else {
/* Give up */
spin_unlock_irqrestore(&(pool->lock), flags);
--
2.29.2
