Re: [net-next PATCH 03/27] swiotlb: Add support for DMA_ATTR_SKIP_CPU_SYNC

From: Konrad Rzeszutek Wilk
Date: Fri Oct 28 2016 - 13:35:02 EST

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In reply to: Alexander Duyck: "[net-next PATCH 03/27] swiotlb: Add support for DMA_ATTR_SKIP_CPU_SYNC"
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On Tue, Oct 25, 2016 at 11:37:03AM -0400, Alexander Duyck wrote:
> As a first step to making DMA_ATTR_SKIP_CPU_SYNC apply to architectures
> beyond just ARM I need to make it so that the swiotlb will respect the
> flag. In order to do that I also need to update the swiotlb-xen since it
> heavily makes use of the functionality.
>
> Cc: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>

I am pretty sure I acked it the RFC. Was there a particular
reason (this is very different from the RFC?) you dropped my ACk?

Thanks.

> Signed-off-by: Alexander Duyck <alexander.h.duyck@xxxxxxxxx>
> ---
> drivers/xen/swiotlb-xen.c | 11 +++++++---
> include/linux/swiotlb.h | 6 ++++--
> lib/swiotlb.c | 48 +++++++++++++++++++++++++++------------------
> 3 files changed, 40 insertions(+), 25 deletions(-)
>
> diff --git a/drivers/xen/swiotlb-xen.c b/drivers/xen/swiotlb-xen.c
> index b8014bf..3d048af 100644
> --- a/drivers/xen/swiotlb-xen.c
> +++ b/drivers/xen/swiotlb-xen.c
> @@ -405,7 +405,8 @@ dma_addr_t xen_swiotlb_map_page(struct device *dev, struct page *page,
> */
> trace_swiotlb_bounced(dev, dev_addr, size, swiotlb_force);
>
> - map = swiotlb_tbl_map_single(dev, start_dma_addr, phys, size, dir);
> + map = swiotlb_tbl_map_single(dev, start_dma_addr, phys, size, dir,
> + attrs);
> if (map == SWIOTLB_MAP_ERROR)
> return DMA_ERROR_CODE;
>
> @@ -419,7 +420,8 @@ dma_addr_t xen_swiotlb_map_page(struct device *dev, struct page *page,
> if (dma_capable(dev, dev_addr, size))
> return dev_addr;
>
> - swiotlb_tbl_unmap_single(dev, map, size, dir);
> + swiotlb_tbl_unmap_single(dev, map, size, dir,
> + attrs | DMA_ATTR_SKIP_CPU_SYNC);
>
> return DMA_ERROR_CODE;
> }
> @@ -445,7 +447,7 @@ static void xen_unmap_single(struct device *hwdev, dma_addr_t dev_addr,
>
> /* NOTE: We use dev_addr here, not paddr! */
> if (is_xen_swiotlb_buffer(dev_addr)) {
> - swiotlb_tbl_unmap_single(hwdev, paddr, size, dir);
> + swiotlb_tbl_unmap_single(hwdev, paddr, size, dir, attrs);
> return;
> }
>
> @@ -558,11 +560,12 @@ void xen_swiotlb_unmap_page(struct device *hwdev, dma_addr_t dev_addr,
> start_dma_addr,
> sg_phys(sg),
> sg->length,
> - dir);
> + dir, attrs);
> if (map == SWIOTLB_MAP_ERROR) {
> dev_warn(hwdev, "swiotlb buffer is full\n");
> /* Don't panic here, we expect map_sg users
> to do proper error handling. */
> + attrs |= DMA_ATTR_SKIP_CPU_SYNC;
> xen_swiotlb_unmap_sg_attrs(hwdev, sgl, i, dir,
> attrs);
> sg_dma_len(sgl) = 0;
> diff --git a/include/linux/swiotlb.h b/include/linux/swiotlb.h
> index e237b6f..4517be9 100644
> --- a/include/linux/swiotlb.h
> +++ b/include/linux/swiotlb.h
> @@ -44,11 +44,13 @@ enum dma_sync_target {
> extern phys_addr_t swiotlb_tbl_map_single(struct device *hwdev,
> dma_addr_t tbl_dma_addr,
> phys_addr_t phys, size_t size,
> - enum dma_data_direction dir);
> + enum dma_data_direction dir,
> + unsigned long attrs);
>
> extern void swiotlb_tbl_unmap_single(struct device *hwdev,
> phys_addr_t tlb_addr,
> - size_t size, enum dma_data_direction dir);
> + size_t size, enum dma_data_direction dir,
> + unsigned long attrs);
>
> extern void swiotlb_tbl_sync_single(struct device *hwdev,
> phys_addr_t tlb_addr,
> diff --git a/lib/swiotlb.c b/lib/swiotlb.c
> index 47aad37..b538d39 100644
> --- a/lib/swiotlb.c
> +++ b/lib/swiotlb.c
> @@ -425,7 +425,8 @@ static void swiotlb_bounce(phys_addr_t orig_addr, phys_addr_t tlb_addr,
> phys_addr_t swiotlb_tbl_map_single(struct device *hwdev,
> dma_addr_t tbl_dma_addr,
> phys_addr_t orig_addr, size_t size,
> - enum dma_data_direction dir)
> + enum dma_data_direction dir,
> + unsigned long attrs)
> {
> unsigned long flags;
> phys_addr_t tlb_addr;
> @@ -526,7 +527,8 @@ phys_addr_t swiotlb_tbl_map_single(struct device *hwdev,
> */
> for (i = 0; i < nslots; i++)
> io_tlb_orig_addr[index+i] = orig_addr + (i << IO_TLB_SHIFT);
> - if (dir == DMA_TO_DEVICE || dir == DMA_BIDIRECTIONAL)
> + if (!(attrs & DMA_ATTR_SKIP_CPU_SYNC) &&
> + (dir == DMA_TO_DEVICE || dir == DMA_BIDIRECTIONAL))
> swiotlb_bounce(orig_addr, tlb_addr, size, DMA_TO_DEVICE);
>
> return tlb_addr;
> @@ -539,18 +541,20 @@ phys_addr_t swiotlb_tbl_map_single(struct device *hwdev,
>
> static phys_addr_t
> map_single(struct device *hwdev, phys_addr_t phys, size_t size,
> - enum dma_data_direction dir)
> + enum dma_data_direction dir, unsigned long attrs)
> {
> dma_addr_t start_dma_addr = phys_to_dma(hwdev, io_tlb_start);
>
> - return swiotlb_tbl_map_single(hwdev, start_dma_addr, phys, size, dir);
> + return swiotlb_tbl_map_single(hwdev, start_dma_addr, phys, size,
> + dir, attrs);
> }
>
> /*
> * dma_addr is the kernel virtual address of the bounce buffer to unmap.
> */
> void swiotlb_tbl_unmap_single(struct device *hwdev, phys_addr_t tlb_addr,
> - size_t size, enum dma_data_direction dir)
> + size_t size, enum dma_data_direction dir,
> + unsigned long attrs)
> {
> unsigned long flags;
> int i, count, nslots = ALIGN(size, 1 << IO_TLB_SHIFT) >> IO_TLB_SHIFT;
> @@ -561,6 +565,7 @@ void swiotlb_tbl_unmap_single(struct device *hwdev, phys_addr_t tlb_addr,
> * First, sync the memory before unmapping the entry
> */
> if (orig_addr != INVALID_PHYS_ADDR &&
> + !(attrs & DMA_ATTR_SKIP_CPU_SYNC) &&
> ((dir == DMA_FROM_DEVICE) || (dir == DMA_BIDIRECTIONAL)))
> swiotlb_bounce(orig_addr, tlb_addr, size, DMA_FROM_DEVICE);
>
> @@ -654,7 +659,8 @@ void swiotlb_tbl_sync_single(struct device *hwdev, phys_addr_t tlb_addr,
> * GFP_DMA memory; fall back on map_single(), which
> * will grab memory from the lowest available address range.
> */
> - phys_addr_t paddr = map_single(hwdev, 0, size, DMA_FROM_DEVICE);
> + phys_addr_t paddr = map_single(hwdev, 0, size,
> + DMA_FROM_DEVICE, 0);
> if (paddr == SWIOTLB_MAP_ERROR)
> goto err_warn;
>
> @@ -669,7 +675,8 @@ void swiotlb_tbl_sync_single(struct device *hwdev, phys_addr_t tlb_addr,
>
> /* DMA_TO_DEVICE to avoid memcpy in unmap_single */
> swiotlb_tbl_unmap_single(hwdev, paddr,
> - size, DMA_TO_DEVICE);
> + size, DMA_TO_DEVICE,
> + DMA_ATTR_SKIP_CPU_SYNC);
> goto err_warn;
> }
> }
> @@ -699,7 +706,7 @@ void swiotlb_tbl_sync_single(struct device *hwdev, phys_addr_t tlb_addr,
> free_pages((unsigned long)vaddr, get_order(size));
> else
> /* DMA_TO_DEVICE to avoid memcpy in swiotlb_tbl_unmap_single */
> - swiotlb_tbl_unmap_single(hwdev, paddr, size, DMA_TO_DEVICE);
> + swiotlb_tbl_unmap_single(hwdev, paddr, size, DMA_TO_DEVICE, 0);
> }
> EXPORT_SYMBOL(swiotlb_free_coherent);
>
> @@ -755,7 +762,7 @@ dma_addr_t swiotlb_map_page(struct device *dev, struct page *page,
> trace_swiotlb_bounced(dev, dev_addr, size, swiotlb_force);
>
> /* Oh well, have to allocate and map a bounce buffer. */
> - map = map_single(dev, phys, size, dir);
> + map = map_single(dev, phys, size, dir, attrs);
> if (map == SWIOTLB_MAP_ERROR) {
> swiotlb_full(dev, size, dir, 1);
> return phys_to_dma(dev, io_tlb_overflow_buffer);
> @@ -764,12 +771,13 @@ dma_addr_t swiotlb_map_page(struct device *dev, struct page *page,
> dev_addr = phys_to_dma(dev, map);
>
> /* Ensure that the address returned is DMA'ble */
> - if (!dma_capable(dev, dev_addr, size)) {
> - swiotlb_tbl_unmap_single(dev, map, size, dir);
> - return phys_to_dma(dev, io_tlb_overflow_buffer);
> - }
> + if (dma_capable(dev, dev_addr, size))
> + return dev_addr;
> +
> + swiotlb_tbl_unmap_single(dev, map, size, dir,
> + attrs | DMA_ATTR_SKIP_CPU_SYNC);
>
> - return dev_addr;
> + return phys_to_dma(dev, io_tlb_overflow_buffer);
> }
> EXPORT_SYMBOL_GPL(swiotlb_map_page);
>
> @@ -782,14 +790,15 @@ dma_addr_t swiotlb_map_page(struct device *dev, struct page *page,
> * whatever the device wrote there.
> */
> static void unmap_single(struct device *hwdev, dma_addr_t dev_addr,
> - size_t size, enum dma_data_direction dir)
> + size_t size, enum dma_data_direction dir,
> + unsigned long attrs)
> {
> phys_addr_t paddr = dma_to_phys(hwdev, dev_addr);
>
> BUG_ON(dir == DMA_NONE);
>
> if (is_swiotlb_buffer(paddr)) {
> - swiotlb_tbl_unmap_single(hwdev, paddr, size, dir);
> + swiotlb_tbl_unmap_single(hwdev, paddr, size, dir, attrs);
> return;
> }
>
> @@ -809,7 +818,7 @@ void swiotlb_unmap_page(struct device *hwdev, dma_addr_t dev_addr,
> size_t size, enum dma_data_direction dir,
> unsigned long attrs)
> {
> - unmap_single(hwdev, dev_addr, size, dir);
> + unmap_single(hwdev, dev_addr, size, dir, attrs);
> }
> EXPORT_SYMBOL_GPL(swiotlb_unmap_page);
>
> @@ -891,7 +900,7 @@ void swiotlb_unmap_page(struct device *hwdev, dma_addr_t dev_addr,
> if (swiotlb_force ||
> !dma_capable(hwdev, dev_addr, sg->length)) {
> phys_addr_t map = map_single(hwdev, sg_phys(sg),
> - sg->length, dir);
> + sg->length, dir, attrs);
> if (map == SWIOTLB_MAP_ERROR) {
> /* Don't panic here, we expect map_sg users
> to do proper error handling. */
> @@ -925,7 +934,8 @@ void swiotlb_unmap_page(struct device *hwdev, dma_addr_t dev_addr,
> BUG_ON(dir == DMA_NONE);
>
> for_each_sg(sgl, sg, nelems, i)
> - unmap_single(hwdev, sg->dma_address, sg_dma_len(sg), dir);
> + unmap_single(hwdev, sg->dma_address, sg_dma_len(sg), dir,
> + attrs);
>
> }
> EXPORT_SYMBOL(swiotlb_unmap_sg_attrs);
>

Next message: Konrad Rzeszutek Wilk: "Re: [net-next PATCH 02/27] swiotlb-xen: Enforce return of DMA_ERROR_CODE in mapping function"
Previous message: Yazen Ghannam: "[PATCH v2 1/2] x86/AMD: Fix cpu_llc_id for AMD Fam17h systems"
In reply to: Alexander Duyck: "[net-next PATCH 03/27] swiotlb: Add support for DMA_ATTR_SKIP_CPU_SYNC"
Next in thread: Alexander Duyck: "Re: [net-next PATCH 03/27] swiotlb: Add support for DMA_ATTR_SKIP_CPU_SYNC"
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