Re: [PATCH v9 1/5] swiotlb: Split size parameter to map/unmap APIs

Konrad Rzeszutek Wilk
2019-09-10T15:15:06Z

On Fri, Sep 06, 2019 at 02:14:48PM +0800, Lu Baolu wrote:
> This splits the size parameter to swiotlb_tbl_map_single() and
> swiotlb_tbl_unmap_single() into an alloc_size and a mapping_size
> parameter, where the latter one is rounded up to the iommu page
> size.

It does a bit more too. You have the WARN_ON. Can you make it be
more verbose (as in details of which device requested it) and also use printk_once or so please?
>
> Suggested-by: Christoph Hellwig <hch@lst.de>
> Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
> Reviewed-by: Christoph Hellwig <hch@lst.de>
> ---
> drivers/xen/swiotlb-xen.c | 8 ++++----
> include/linux/swiotlb.h | 8 ++++++--
> kernel/dma/direct.c | 2 +-
> kernel/dma/swiotlb.c | 30 +++++++++++++++++++-----------
> 4 files changed, 30 insertions(+), 18 deletions(-)
>
> diff --git a/drivers/xen/swiotlb-xen.c b/drivers/xen/swiotlb-xen.c
> index ae1df496bf38..adcabd9473eb 100644
> --- a/drivers/xen/swiotlb-xen.c
> +++ b/drivers/xen/swiotlb-xen.c
> @@ -386,8 +386,8 @@ static 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,
> - attrs);
> + map = swiotlb_tbl_map_single(dev, start_dma_addr, phys,
> + size, size, dir, attrs);
> if (map == (phys_addr_t)DMA_MAPPING_ERROR)
> return DMA_MAPPING_ERROR;
>
> @@ -397,7 +397,7 @@ static dma_addr_t xen_swiotlb_map_page(struct device *dev, struct page *page,
> * Ensure that the address returned is DMA'ble
> */
> if (unlikely(!dma_capable(dev, dev_addr, size))) {
> - swiotlb_tbl_unmap_single(dev, map, size, dir,
> + swiotlb_tbl_unmap_single(dev, map, size, size, dir,
> attrs | DMA_ATTR_SKIP_CPU_SYNC);
> return DMA_MAPPING_ERROR;
> }
> @@ -433,7 +433,7 @@ 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, attrs);
> + swiotlb_tbl_unmap_single(hwdev, paddr, size, size, dir, attrs);
> }
>
> static void xen_swiotlb_unmap_page(struct device *hwdev, dma_addr_t dev_addr,
> diff --git a/include/linux/swiotlb.h b/include/linux/swiotlb.h
> index 361f62bb4a8e..cde3dc18e21a 100644
> --- a/include/linux/swiotlb.h
> +++ b/include/linux/swiotlb.h
> @@ -46,13 +46,17 @@ 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,
> + phys_addr_t phys,
> + size_t mapping_size,
> + size_t alloc_size,
> 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 mapping_size,
> + size_t alloc_size,
> + enum dma_data_direction dir,
> unsigned long attrs);
>
> extern void swiotlb_tbl_sync_single(struct device *hwdev,
> diff --git a/kernel/dma/direct.c b/kernel/dma/direct.c
> index 706113c6bebc..8402b29c280f 100644
> --- a/kernel/dma/direct.c
> +++ b/kernel/dma/direct.c
> @@ -305,7 +305,7 @@ void dma_direct_unmap_page(struct device *dev, dma_addr_t addr,
> dma_direct_sync_single_for_cpu(dev, addr, size, dir);
>
> if (unlikely(is_swiotlb_buffer(phys)))
> - swiotlb_tbl_unmap_single(dev, phys, size, dir, attrs);
> + swiotlb_tbl_unmap_single(dev, phys, size, size, dir, attrs);
> }
> EXPORT_SYMBOL(dma_direct_unmap_page);
>
> diff --git a/kernel/dma/swiotlb.c b/kernel/dma/swiotlb.c
> index 9de232229063..89066efa3840 100644
> --- a/kernel/dma/swiotlb.c
> +++ b/kernel/dma/swiotlb.c
> @@ -444,7 +444,9 @@ 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,
> + phys_addr_t orig_addr,
> + size_t mapping_size,
> + size_t alloc_size,
> enum dma_data_direction dir,
> unsigned long attrs)
> {
> @@ -464,6 +466,9 @@ phys_addr_t swiotlb_tbl_map_single(struct device *hwdev,
> pr_warn_once("%s is active and system is using DMA bounce buffers\n",
> sme_active() ? "SME" : "SEV");
>
> + if (WARN_ON(mapping_size > alloc_size))
> + return (phys_addr_t)DMA_MAPPING_ERROR;
> +
> mask = dma_get_seg_boundary(hwdev);
>
> tbl_dma_addr &= mask;
> @@ -481,8 +486,8 @@ phys_addr_t swiotlb_tbl_map_single(struct device *hwdev,
> * For mappings greater than or equal to a page, we limit the stride
> * (and hence alignment) to a page size.
> */
> - nslots = ALIGN(size, 1 << IO_TLB_SHIFT) >> IO_TLB_SHIFT;
> - if (size >= PAGE_SIZE)
> + nslots = ALIGN(alloc_size, 1 << IO_TLB_SHIFT) >> IO_TLB_SHIFT;
> + if (alloc_size >= PAGE_SIZE)
> stride = (1 << (PAGE_SHIFT - IO_TLB_SHIFT));
> else
> stride = 1;
> @@ -547,7 +552,7 @@ phys_addr_t swiotlb_tbl_map_single(struct device *hwdev,
> spin_unlock_irqrestore(&io_tlb_lock, flags);
> if (!(attrs & DMA_ATTR_NO_WARN) && printk_ratelimit())
> dev_warn(hwdev, "swiotlb buffer is full (sz: %zd bytes), total %lu (slots), used %lu (slots)\n",
> - size, io_tlb_nslabs, tmp_io_tlb_used);
> + alloc_size, io_tlb_nslabs, tmp_io_tlb_used);
> return (phys_addr_t)DMA_MAPPING_ERROR;
> found:
> io_tlb_used += nslots;
> @@ -562,7 +567,7 @@ phys_addr_t swiotlb_tbl_map_single(struct device *hwdev,
> io_tlb_orig_addr[index+i] = orig_addr + (i << IO_TLB_SHIFT);
> if (!(attrs & DMA_ATTR_SKIP_CPU_SYNC) &&
> (dir == DMA_TO_DEVICE || dir == DMA_BIDIRECTIONAL))
> - swiotlb_bounce(orig_addr, tlb_addr, size, DMA_TO_DEVICE);
> + swiotlb_bounce(orig_addr, tlb_addr, mapping_size, DMA_TO_DEVICE);
>
> return tlb_addr;
> }
> @@ -571,21 +576,24 @@ phys_addr_t swiotlb_tbl_map_single(struct device *hwdev,
> * tlb_addr is the physical 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,
> - unsigned long attrs)
> + size_t mapping_size, size_t alloc_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;
> + int i, count, nslots = ALIGN(alloc_size, 1 << IO_TLB_SHIFT) >> IO_TLB_SHIFT;
> int index = (tlb_addr - io_tlb_start) >> IO_TLB_SHIFT;
> phys_addr_t orig_addr = io_tlb_orig_addr[index];
>
> + if (WARN_ON(mapping_size > alloc_size))
> + return;
> +
> /*
> * 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);
> + swiotlb_bounce(orig_addr, tlb_addr, mapping_size, DMA_FROM_DEVICE);
>
> /*
> * Return the buffer to the free list by setting the corresponding
> @@ -665,14 +673,14 @@ bool swiotlb_map(struct device *dev, phys_addr_t *phys, dma_addr_t *dma_addr,
>
> /* Oh well, have to allocate and map a bounce buffer. */
> *phys = swiotlb_tbl_map_single(dev, __phys_to_dma(dev, io_tlb_start),
> - *phys, size, dir, attrs);
> + *phys, size, size, dir, attrs);
> if (*phys == (phys_addr_t)DMA_MAPPING_ERROR)
> return false;
>
> /* Ensure that the address returned is DMA'ble */
> *dma_addr = __phys_to_dma(dev, *phys);
> if (unlikely(!dma_capable(dev, *dma_addr, size))) {
> - swiotlb_tbl_unmap_single(dev, *phys, size, dir,
> + swiotlb_tbl_unmap_single(dev, *phys, size, size, dir,
> attrs | DMA_ATTR_SKIP_CPU_SYNC);
> return false;
> }
> --
> 2.17.1
>