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Merge branch 'stable/for-linus-5.2' of git:https://git.kernel.org/pub/scm/l…
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…inux/kernel/git/konrad/swiotlb

Pull swiotlb updates from Konrad Rzeszutek Wilk:
 "Cleanups in the swiotlb code and extra debugfs knobs to help with the
  field diagnostics"

* 'stable/for-linus-5.2' of git:https://git.kernel.org/pub/scm/linux/kernel/git/konrad/swiotlb:
  swiotlb-xen: ensure we have a single callsite for xen_dma_map_page
  swiotlb-xen: simplify the DMA sync method implementations
  swiotlb-xen: use ->map_page to implement ->map_sg
  swiotlb-xen: make instances match their method names
  swiotlb: save io_tlb_used to local variable before leaving critical section
  swiotlb: dump used and total slots when swiotlb buffer is full
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@torvalds
torvalds committed May 8, 2019
2 parents e4eaa9e + 063b827 commit 498e863
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Showing 2 changed files with 64 additions and 138 deletions.
196 changes: 59 additions & 137 deletions drivers/xen/swiotlb-xen.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -391,13 +391,8 @@ static dma_addr_t xen_swiotlb_map_page(struct device *dev, struct page *page,
if (dma_capable(dev, dev_addr, size) &&
!range_straddles_page_boundary(phys, size) &&
!xen_arch_need_swiotlb(dev, phys, dev_addr) &&
(swiotlb_force != SWIOTLB_FORCE)) {
/* we are not interested in the dma_addr returned by
* xen_dma_map_page, only in the potential cache flushes executed
* by the function. */
xen_dma_map_page(dev, page, dev_addr, offset, size, dir, attrs);
return dev_addr;
}
swiotlb_force != SWIOTLB_FORCE)
goto done;

/*
* Oh well, have to allocate and map a bounce buffer.
Expand All @@ -410,19 +405,25 @@ static dma_addr_t xen_swiotlb_map_page(struct device *dev, struct page *page,
return DMA_MAPPING_ERROR;

dev_addr = xen_phys_to_bus(map);
xen_dma_map_page(dev, pfn_to_page(map >> PAGE_SHIFT),
dev_addr, map & ~PAGE_MASK, size, dir, attrs);

/*
* Ensure that the address returned is DMA'ble
*/
if (dma_capable(dev, dev_addr, size))
return dev_addr;

attrs |= DMA_ATTR_SKIP_CPU_SYNC;
swiotlb_tbl_unmap_single(dev, map, size, dir, attrs);
if (unlikely(!dma_capable(dev, dev_addr, size))) {
swiotlb_tbl_unmap_single(dev, map, size, dir,
attrs | DMA_ATTR_SKIP_CPU_SYNC);
return DMA_MAPPING_ERROR;
}

return DMA_MAPPING_ERROR;
page = pfn_to_page(map >> PAGE_SHIFT);
offset = map & ~PAGE_MASK;
done:
/*
* we are not interested in the dma_addr returned by xen_dma_map_page,
* only in the potential cache flushes executed by the function.
*/
xen_dma_map_page(dev, page, dev_addr, offset, size, dir, attrs);
return dev_addr;
}

/*
Expand Down Expand Up @@ -455,58 +456,37 @@ static void xen_swiotlb_unmap_page(struct device *hwdev, dma_addr_t dev_addr,
xen_unmap_single(hwdev, dev_addr, size, dir, attrs);
}

/*
* Make physical memory consistent for a single streaming mode DMA translation
* after a transfer.
*
* If you perform a xen_swiotlb_map_page() but wish to interrogate the buffer
* using the cpu, yet do not wish to teardown the dma mapping, you must
* call this function before doing so. At the next point you give the dma
* address back to the card, you must first perform a
* xen_swiotlb_dma_sync_for_device, and then the device again owns the buffer
*/
static void
xen_swiotlb_sync_single(struct device *hwdev, dma_addr_t dev_addr,
size_t size, enum dma_data_direction dir,
enum dma_sync_target target)
xen_swiotlb_sync_single_for_cpu(struct device *dev, dma_addr_t dma_addr,
size_t size, enum dma_data_direction dir)
{
phys_addr_t paddr = xen_bus_to_phys(dev_addr);

BUG_ON(dir == DMA_NONE);

if (target == SYNC_FOR_CPU)
xen_dma_sync_single_for_cpu(hwdev, dev_addr, size, dir);
phys_addr_t paddr = xen_bus_to_phys(dma_addr);

/* NOTE: We use dev_addr here, not paddr! */
if (is_xen_swiotlb_buffer(dev_addr))
swiotlb_tbl_sync_single(hwdev, paddr, size, dir, target);
xen_dma_sync_single_for_cpu(dev, dma_addr, size, dir);

if (target == SYNC_FOR_DEVICE)
xen_dma_sync_single_for_device(hwdev, dev_addr, size, dir);
if (is_xen_swiotlb_buffer(dma_addr))
swiotlb_tbl_sync_single(dev, paddr, size, dir, SYNC_FOR_CPU);
}

void
xen_swiotlb_sync_single_for_cpu(struct device *hwdev, dma_addr_t dev_addr,
size_t size, enum dma_data_direction dir)
static void
xen_swiotlb_sync_single_for_device(struct device *dev, dma_addr_t dma_addr,
size_t size, enum dma_data_direction dir)
{
xen_swiotlb_sync_single(hwdev, dev_addr, size, dir, SYNC_FOR_CPU);
}
phys_addr_t paddr = xen_bus_to_phys(dma_addr);

void
xen_swiotlb_sync_single_for_device(struct device *hwdev, dma_addr_t dev_addr,
size_t size, enum dma_data_direction dir)
{
xen_swiotlb_sync_single(hwdev, dev_addr, size, dir, SYNC_FOR_DEVICE);
if (is_xen_swiotlb_buffer(dma_addr))
swiotlb_tbl_sync_single(dev, paddr, size, dir, SYNC_FOR_DEVICE);

xen_dma_sync_single_for_device(dev, dma_addr, size, dir);
}

/*
* Unmap a set of streaming mode DMA translations. Again, cpu read rules
* concerning calls here are the same as for swiotlb_unmap_page() above.
*/
static void
xen_swiotlb_unmap_sg_attrs(struct device *hwdev, struct scatterlist *sgl,
int nelems, enum dma_data_direction dir,
unsigned long attrs)
xen_swiotlb_unmap_sg(struct device *hwdev, struct scatterlist *sgl, int nelems,
enum dma_data_direction dir, unsigned long attrs)
{
struct scatterlist *sg;
int i;
Expand All @@ -518,112 +498,54 @@ xen_swiotlb_unmap_sg_attrs(struct device *hwdev, struct scatterlist *sgl,

}

/*
* Map a set of buffers described by scatterlist in streaming mode for DMA.
* This is the scatter-gather version of the above xen_swiotlb_map_page
* interface. Here the scatter gather list elements are each tagged with the
* appropriate dma address and length. They are obtained via
* sg_dma_{address,length}(SG).
*
* NOTE: An implementation may be able to use a smaller number of
* DMA address/length pairs than there are SG table elements.
* (for example via virtual mapping capabilities)
* The routine returns the number of addr/length pairs actually
* used, at most nents.
*
* Device ownership issues as mentioned above for xen_swiotlb_map_page are the
* same here.
*/
static int
xen_swiotlb_map_sg_attrs(struct device *hwdev, struct scatterlist *sgl,
int nelems, enum dma_data_direction dir,
unsigned long attrs)
xen_swiotlb_map_sg(struct device *dev, struct scatterlist *sgl, int nelems,
enum dma_data_direction dir, unsigned long attrs)
{
struct scatterlist *sg;
int i;

BUG_ON(dir == DMA_NONE);

for_each_sg(sgl, sg, nelems, i) {
phys_addr_t paddr = sg_phys(sg);
dma_addr_t dev_addr = xen_phys_to_bus(paddr);

if (swiotlb_force == SWIOTLB_FORCE ||
xen_arch_need_swiotlb(hwdev, paddr, dev_addr) ||
!dma_capable(hwdev, dev_addr, sg->length) ||
range_straddles_page_boundary(paddr, sg->length)) {
phys_addr_t map = swiotlb_tbl_map_single(hwdev,
start_dma_addr,
sg_phys(sg),
sg->length,
dir, attrs);
if (map == DMA_MAPPING_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;
return 0;
}
dev_addr = xen_phys_to_bus(map);
xen_dma_map_page(hwdev, pfn_to_page(map >> PAGE_SHIFT),
dev_addr,
map & ~PAGE_MASK,
sg->length,
dir,
attrs);
sg->dma_address = dev_addr;
} else {
/* we are not interested in the dma_addr returned by
* xen_dma_map_page, only in the potential cache flushes executed
* by the function. */
xen_dma_map_page(hwdev, pfn_to_page(paddr >> PAGE_SHIFT),
dev_addr,
paddr & ~PAGE_MASK,
sg->length,
dir,
attrs);
sg->dma_address = dev_addr;
}
sg->dma_address = xen_swiotlb_map_page(dev, sg_page(sg),
sg->offset, sg->length, dir, attrs);
if (sg->dma_address == DMA_MAPPING_ERROR)
goto out_unmap;
sg_dma_len(sg) = sg->length;
}

return nelems;
out_unmap:
xen_swiotlb_unmap_sg(dev, sgl, i, dir, attrs | DMA_ATTR_SKIP_CPU_SYNC);
sg_dma_len(sgl) = 0;
return 0;
}

/*
* Make physical memory consistent for a set of streaming mode DMA translations
* after a transfer.
*
* The same as swiotlb_sync_single_* but for a scatter-gather list, same rules
* and usage.
*/
static void
xen_swiotlb_sync_sg(struct device *hwdev, struct scatterlist *sgl,
int nelems, enum dma_data_direction dir,
enum dma_sync_target target)
xen_swiotlb_sync_sg_for_cpu(struct device *dev, struct scatterlist *sgl,
int nelems, enum dma_data_direction dir)
{
struct scatterlist *sg;
int i;

for_each_sg(sgl, sg, nelems, i)
xen_swiotlb_sync_single(hwdev, sg->dma_address,
sg_dma_len(sg), dir, target);
}

static void
xen_swiotlb_sync_sg_for_cpu(struct device *hwdev, struct scatterlist *sg,
int nelems, enum dma_data_direction dir)
{
xen_swiotlb_sync_sg(hwdev, sg, nelems, dir, SYNC_FOR_CPU);
for_each_sg(sgl, sg, nelems, i) {
xen_swiotlb_sync_single_for_cpu(dev, sg->dma_address,
sg->length, dir);
}
}

static void
xen_swiotlb_sync_sg_for_device(struct device *hwdev, struct scatterlist *sg,
xen_swiotlb_sync_sg_for_device(struct device *dev, struct scatterlist *sgl,
int nelems, enum dma_data_direction dir)
{
xen_swiotlb_sync_sg(hwdev, sg, nelems, dir, SYNC_FOR_DEVICE);
struct scatterlist *sg;
int i;

for_each_sg(sgl, sg, nelems, i) {
xen_swiotlb_sync_single_for_device(dev, sg->dma_address,
sg->length, dir);
}
}

/*
Expand Down Expand Up @@ -690,8 +612,8 @@ const struct dma_map_ops xen_swiotlb_dma_ops = {
.sync_single_for_device = xen_swiotlb_sync_single_for_device,
.sync_sg_for_cpu = xen_swiotlb_sync_sg_for_cpu,
.sync_sg_for_device = xen_swiotlb_sync_sg_for_device,
.map_sg = xen_swiotlb_map_sg_attrs,
.unmap_sg = xen_swiotlb_unmap_sg_attrs,
.map_sg = xen_swiotlb_map_sg,
.unmap_sg = xen_swiotlb_unmap_sg,
.map_page = xen_swiotlb_map_page,
.unmap_page = xen_swiotlb_unmap_page,
.dma_supported = xen_swiotlb_dma_supported,
Expand Down
6 changes: 5 additions & 1 deletion kernel/dma/swiotlb.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -452,6 +452,7 @@ phys_addr_t swiotlb_tbl_map_single(struct device *hwdev,
unsigned long mask;
unsigned long offset_slots;
unsigned long max_slots;
unsigned long tmp_io_tlb_used;

if (no_iotlb_memory)
panic("Can not allocate SWIOTLB buffer earlier and can't now provide you with the DMA bounce buffer");
Expand Down Expand Up @@ -538,9 +539,12 @@ phys_addr_t swiotlb_tbl_map_single(struct device *hwdev,
} while (index != wrap);

not_found:
tmp_io_tlb_used = io_tlb_used;

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)\n", size);
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);
return DMA_MAPPING_ERROR;
found:
io_tlb_used += nslots;
Expand Down

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