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swiotlb: provide swiotlb_init variants that remap the buffer 

To shared more code between swiotlb and xen-swiotlb, offer a
swiotlb_init_remap interface and add a remap callback to
swiotlb_init_late that will allow Xen to remap the buffer without
duplicating much of the logic.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Tested-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
This commit is contained in:
Christoph Hellwig 2022-03-14 08:02:57 +01:00
parent 742519538e
commit 7374153d29
3 changed files with 38 additions and 5 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
arch/x86/pci/sta2x11-fixup.c
View File

@ -57,7 +57,7 @@ static void sta2x11_new_instance(struct pci_dev *pdev)
int size = STA2X11_SWIOTLB_SIZE;
/* First instance: register your own swiotlb area */
dev_info(&pdev->dev, "Using SWIOTLB (size %i)\n", size);
if (swiotlb_init_late(size, GFP_DMA))
if (swiotlb_init_late(size, GFP_DMA, NULL))
dev_emerg(&pdev->dev, "init swiotlb failed\n");
}
list_add(&instance->list, &sta2x11_instance_list);

5
include/linux/swiotlb.h
View File

@ -36,8 +36,11 @@ struct scatterlist;
int swiotlb_init_with_tbl(char *tlb, unsigned long nslabs, unsigned int flags);
unsigned long swiotlb_size_or_default(void);
void __init swiotlb_init_remap(bool addressing_limit, unsigned int flags,
int (*remap)(void *tlb, unsigned long nslabs));
int swiotlb_init_late(size_t size, gfp_t gfp_mask,
int (*remap)(void *tlb, unsigned long nslabs));
extern int swiotlb_late_init_with_tbl(char *tlb, unsigned long nslabs);
int swiotlb_init_late(size_t size, gfp_t gfp_mask);
extern void __init swiotlb_update_mem_attributes(void);
phys_addr_t swiotlb_tbl_map_single(struct device *hwdev, phys_addr_t phys,

36
kernel/dma/swiotlb.c
View File

@ -256,9 +256,11 @@ int __init swiotlb_init_with_tbl(char *tlb, unsigned long nslabs,
* Statically reserve bounce buffer space and initialize bounce buffer data
* structures for the software IO TLB used to implement the DMA API.
*/
void __init swiotlb_init(bool addressing_limit, unsigned int flags)
void __init swiotlb_init_remap(bool addressing_limit, unsigned int flags,
int (*remap)(void *tlb, unsigned long nslabs))
{
size_t bytes = PAGE_ALIGN(default_nslabs << IO_TLB_SHIFT);
unsigned long nslabs = default_nslabs;
size_t bytes;
void *tlb;
if (!addressing_limit && !swiotlb_force_bounce)
@ -271,12 +273,23 @@ void __init swiotlb_init(bool addressing_limit, unsigned int flags)
* allow to pick a location everywhere for hypervisors with guest
* memory encryption.
*/
retry:
bytes = PAGE_ALIGN(default_nslabs << IO_TLB_SHIFT);
if (flags & SWIOTLB_ANY)
tlb = memblock_alloc(bytes, PAGE_SIZE);
else
tlb = memblock_alloc_low(bytes, PAGE_SIZE);
if (!tlb)
goto fail;
if (remap && remap(tlb, nslabs) < 0) {
memblock_free(tlb, PAGE_ALIGN(bytes));
nslabs = ALIGN(nslabs >> 1, IO_TLB_SEGSIZE);
if (nslabs < IO_TLB_MIN_SLABS)
panic("%s: Failed to remap %zu bytes\n",
__func__, bytes);
goto retry;
}
if (swiotlb_init_with_tbl(tlb, default_nslabs, flags))
goto fail_free_mem;
return;
@ -287,12 +300,18 @@ fail:
pr_warn("Cannot allocate buffer");
}
void __init swiotlb_init(bool addressing_limit, unsigned int flags)
{
return swiotlb_init_remap(addressing_limit, flags, NULL);
}
/*
* Systems with larger DMA zones (those that don't support ISA) can
* initialize the swiotlb later using the slab allocator if needed.
* This should be just like above, but with some error catching.
*/
int swiotlb_init_late(size_t size, gfp_t gfp_mask)
int swiotlb_init_late(size_t size, gfp_t gfp_mask,
int (*remap)(void *tlb, unsigned long nslabs))
{
unsigned long nslabs = ALIGN(size >> IO_TLB_SHIFT, IO_TLB_SEGSIZE);
unsigned long bytes;
@ -303,6 +322,7 @@ int swiotlb_init_late(size_t size, gfp_t gfp_mask)
if (swiotlb_force_disable)
return 0;
retry:
order = get_order(nslabs << IO_TLB_SHIFT);
nslabs = SLABS_PER_PAGE << order;
bytes = nslabs << IO_TLB_SHIFT;
@ -323,6 +343,16 @@ int swiotlb_init_late(size_t size, gfp_t gfp_mask)
(PAGE_SIZE << order) >> 20);
nslabs = SLABS_PER_PAGE << order;
}
if (remap)
rc = remap(vstart, nslabs);
if (rc) {
free_pages((unsigned long)vstart, order);
nslabs = ALIGN(nslabs >> 1, IO_TLB_SEGSIZE);
if (nslabs < IO_TLB_MIN_SLABS)
return rc;
goto retry;
}
rc = swiotlb_late_init_with_tbl(vstart, nslabs);
if (rc)
free_pages((unsigned long)vstart, order);