Re: [PATCH v4 12/14] swiotlb: Add restricted DMA alloc/free support.

[Claire Chang]

On Fri, Feb 26, 2021 at 1:17 PM Christoph Hellwig  wrote:
>
> On Fri, Feb 26, 2021 at 12:17:50PM +0800, Claire Chang wrote:
> > Do you think I should fix this and rebase on the latest linux-next
> > now? I wonder if there are more factor and clean up coming and I
> > should wait after that.
>
> Here is my preferred plan:
>
>  1) wait for my series to support the min alignment in swiotlb to
> land in Linus tree
>  2) I'll resend my series with the further swiotlb cleanup and
> refactoring, which includes a slightly rebased version of your
> patch to add the io_tlb_mem structure
>  3) resend your series on top of that as a baseline
>
> This is my current WIP tree for 2:
>
>   
> http://git.infradead.org/users/hch/misc.git/shortlog/refs/heads/swiotlb-struct

Sounds good to me. Thanks!

Re: [PATCH v4 12/14] swiotlb: Add restricted DMA alloc/free support.

[Christoph Hellwig]

On Fri, Feb 26, 2021 at 12:17:50PM +0800, Claire Chang wrote:
> Do you think I should fix this and rebase on the latest linux-next
> now? I wonder if there are more factor and clean up coming and I
> should wait after that.

Here is my preferred plan:

 1) wait for my series to support the min alignment in swiotlb to
land in Linus tree
 2) I'll resend my series with the further swiotlb cleanup and
refactoring, which includes a slightly rebased version of your
patch to add the io_tlb_mem structure
 3) resend your series on top of that as a baseline

This is my current WIP tree for 2:

  http://git.infradead.org/users/hch/misc.git/shortlog/refs/heads/swiotlb-struct

Re: [PATCH v4 12/14] swiotlb: Add restricted DMA alloc/free support.

[Claire Chang]

> diff --git a/kernel/dma/swiotlb.c b/kernel/dma/swiotlb.c
> index fd9c1bd183ac..8b77fd64199e 100644
> --- a/kernel/dma/swiotlb.c
> +++ b/kernel/dma/swiotlb.c
> @@ -836,6 +836,40 @@ late_initcall(swiotlb_create_default_debugfs);
>  #endif
>
>  #ifdef CONFIG_DMA_RESTRICTED_POOL
> +struct page *dev_swiotlb_alloc(struct device *dev, size_t size, gfp_t gfp)
> +{
> +   struct swiotlb *swiotlb;
> +   phys_addr_t tlb_addr;
> +   unsigned int index;
> +
> +   /* dev_swiotlb_alloc can be used only in the context which permits 
> sleeping. */
> +   if (!dev->dev_swiotlb || !gfpflags_allow_blocking(gfp))

Just noticed that !gfpflags_allow_blocking(gfp) shouldn't be here.

Hi Christoph,

Do you think I should fix this and rebase on the latest linux-next
now? I wonder if there are more factor and clean up coming and I
should wait after that.

Thanks,
Claire

[PATCH v4 12/14] swiotlb: Add restricted DMA alloc/free support.

[Claire Chang]

Add the functions, dev_swiotlb_{alloc,free} to support the memory
allocation from restricted DMA pool.

Signed-off-by: Claire Chang 
---
 include/linux/swiotlb.h |  2 ++
 kernel/dma/direct.c | 30 ++
 kernel/dma/swiotlb.c| 34 ++
 3 files changed, 58 insertions(+), 8 deletions(-)

diff --git a/include/linux/swiotlb.h b/include/linux/swiotlb.h
index b9f2a250c8da..2cd39e102915 100644
--- a/include/linux/swiotlb.h
+++ b/include/linux/swiotlb.h
@@ -74,6 +74,8 @@ extern enum swiotlb_force swiotlb_force;
 #ifdef CONFIG_DMA_RESTRICTED_POOL
 bool is_swiotlb_force(struct device *dev);
 bool is_dev_swiotlb_force(struct device *dev);
+struct page *dev_swiotlb_alloc(struct device *dev, size_t size, gfp_t gfp);
+bool dev_swiotlb_free(struct device *dev, struct page *page, size_t size);
 #else
 static inline bool is_swiotlb_force(struct device *dev)
 {
diff --git a/kernel/dma/direct.c b/kernel/dma/direct.c
index a76a1a2f24da..f9a9321f7559 100644
--- a/kernel/dma/direct.c
+++ b/kernel/dma/direct.c
@@ -12,6 +12,7 @@
 #include 
 #include 
 #include 
+#include 
 #include 
 #include "direct.h"
 
@@ -77,6 +78,10 @@ static bool dma_coherent_ok(struct device *dev, phys_addr_t 
phys, size_t size)
 
 static void __dma_direct_free_pages(struct device *dev, struct page *page, 
size_t size)
 {
+#ifdef CONFIG_DMA_RESTRICTED_POOL
+   if (dev_swiotlb_free(dev, page, size))
+   return;
+#endif
dma_free_contiguous(dev, page, size);
 }
 
@@ -89,6 +94,12 @@ static struct page *__dma_direct_alloc_pages(struct device 
*dev, size_t size,
 
WARN_ON_ONCE(!PAGE_ALIGNED(size));
 
+#ifdef CONFIG_DMA_RESTRICTED_POOL
+   page = dev_swiotlb_alloc(dev, size, gfp);
+   if (page)
+   return page;
+#endif
+
gfp |= dma_direct_optimal_gfp_mask(dev, dev->coherent_dma_mask,
   _limit);
page = dma_alloc_contiguous(dev, size, gfp);
@@ -147,7 +158,7 @@ void *dma_direct_alloc(struct device *dev, size_t size,
gfp |= __GFP_NOWARN;
 
if ((attrs & DMA_ATTR_NO_KERNEL_MAPPING) &&
-   !force_dma_unencrypted(dev)) {
+   !force_dma_unencrypted(dev) && !is_dev_swiotlb_force(dev)) {
page = __dma_direct_alloc_pages(dev, size, gfp & ~__GFP_ZERO);
if (!page)
return NULL;
@@ -160,8 +171,8 @@ void *dma_direct_alloc(struct device *dev, size_t size,
}
 
if (!IS_ENABLED(CONFIG_ARCH_HAS_DMA_SET_UNCACHED) &&
-   !IS_ENABLED(CONFIG_DMA_DIRECT_REMAP) &&
-   !dev_is_dma_coherent(dev))
+   !IS_ENABLED(CONFIG_DMA_DIRECT_REMAP) && !dev_is_dma_coherent(dev) &&
+   !is_dev_swiotlb_force(dev))
return arch_dma_alloc(dev, size, dma_handle, gfp, attrs);
 
/*
@@ -171,7 +182,9 @@ void *dma_direct_alloc(struct device *dev, size_t size,
if (IS_ENABLED(CONFIG_DMA_COHERENT_POOL) &&
!gfpflags_allow_blocking(gfp) &&
(force_dma_unencrypted(dev) ||
-(IS_ENABLED(CONFIG_DMA_DIRECT_REMAP) && 
!dev_is_dma_coherent(dev
+(IS_ENABLED(CONFIG_DMA_DIRECT_REMAP) &&
+ !dev_is_dma_coherent(dev))) &&
+   !is_dev_swiotlb_force(dev))
return dma_direct_alloc_from_pool(dev, size, dma_handle, gfp);
 
/* we always manually zero the memory once we are done */
@@ -252,15 +265,15 @@ void dma_direct_free(struct device *dev, size_t size,
unsigned int page_order = get_order(size);
 
if ((attrs & DMA_ATTR_NO_KERNEL_MAPPING) &&
-   !force_dma_unencrypted(dev)) {
+   !force_dma_unencrypted(dev) && !is_dev_swiotlb_force(dev)) {
/* cpu_addr is a struct page cookie, not a kernel address */
dma_free_contiguous(dev, cpu_addr, size);
return;
}
 
if (!IS_ENABLED(CONFIG_ARCH_HAS_DMA_SET_UNCACHED) &&
-   !IS_ENABLED(CONFIG_DMA_DIRECT_REMAP) &&
-   !dev_is_dma_coherent(dev)) {
+   !IS_ENABLED(CONFIG_DMA_DIRECT_REMAP) && !dev_is_dma_coherent(dev) &&
+   !is_dev_swiotlb_force(dev)) {
arch_dma_free(dev, size, cpu_addr, dma_addr, attrs);
return;
}
@@ -288,7 +301,8 @@ struct page *dma_direct_alloc_pages(struct device *dev, 
size_t size,
void *ret;
 
if (IS_ENABLED(CONFIG_DMA_COHERENT_POOL) &&
-   force_dma_unencrypted(dev) && !gfpflags_allow_blocking(gfp))
+   force_dma_unencrypted(dev) && !gfpflags_allow_blocking(gfp) &&
+   !is_dev_swiotlb_force(dev))
return dma_direct_alloc_from_pool(dev, size, dma_handle, gfp);
 
page = __dma_direct_alloc_pages(dev, size, gfp);
diff --git a/kernel/dma/swiotlb.c b/kernel/dma/swiotlb.c
index fd9c1bd183ac..8b77fd64199e 100644
--- a/kernel/dma/swiotlb.c
+++ b/kernel/dma/swiotlb.c
@@ -836,6 +836,40 @@ late_initcall(swiotlb_create_default_debugfs);