Commit 7453c549 authored by Konrad Rzeszutek Wilk's avatar Konrad Rzeszutek Wilk Committed by Konrad Rzeszutek Wilk
Browse files

swiotlb: Export swiotlb_max_segment to users 



So they can figure out what is the optimal number of pages
that can be contingously stitched together without fear of
bounce buffer.

We also expose an mechanism for sub-users of SWIOTLB API, such
as Xen-SWIOTLB to set the max segment value. And lastly
if swiotlb=force is set (which mandates we bounce buffer everything)
we set max_segment so at least we can bounce buffer one 4K page
instead of a giant 512KB one for which we may not have space.

Signed-off-by: default avatarKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Reported-and-Tested-by: default avatarJuergen Gross <jgross@suse.com>
parent fff5d992

drivers/gpu/drm/i915/i915_gem.c

+1 −10
Original line number Diff line number Diff line
@@ -2290,15 +2290,6 @@ unlock: 
	mutex_unlock(&obj->mm.lock);

}



static unsigned int swiotlb_max_size(void)

{

#if IS_ENABLED(CONFIG_SWIOTLB)

	return rounddown(swiotlb_nr_tbl() << IO_TLB_SHIFT, PAGE_SIZE);

#else

	return 0;

#endif

}



static void i915_sg_trim(struct sg_table *orig_st)

{

	struct sg_table new_st;
@@ -2345,7 +2336,7 @@ i915_gem_object_get_pages_gtt(struct drm_i915_gem_object *obj) 
	GEM_BUG_ON(obj->base.read_domains & I915_GEM_GPU_DOMAINS);

	GEM_BUG_ON(obj->base.write_domain & I915_GEM_GPU_DOMAINS);



	max_segment = swiotlb_max_size();

	max_segment = swiotlb_max_segment();

	if (!max_segment)

		max_segment = rounddown(UINT_MAX, PAGE_SIZE);

drivers/xen/swiotlb-xen.c

+4 −0
Original line number Diff line number Diff line
@@ -275,6 +275,10 @@ retry: 
		rc = 0;

	} else

		rc = swiotlb_late_init_with_tbl(xen_io_tlb_start, xen_io_tlb_nslabs);



	if (!rc)

		swiotlb_set_max_segment(PAGE_SIZE);



	return rc;

error:

	if (repeat--) {

include/linux/swiotlb.h

+3 −0
Original line number Diff line number Diff line
@@ -114,11 +114,14 @@ swiotlb_dma_supported(struct device *hwdev, u64 mask); 


#ifdef CONFIG_SWIOTLB

extern void __init swiotlb_free(void);

unsigned int swiotlb_max_segment(void);

#else

static inline void swiotlb_free(void) { }

static inline unsigned int swiotlb_max_segment(void) { return 0; }

#endif



extern void swiotlb_print_info(void);

extern int is_swiotlb_buffer(phys_addr_t paddr);

extern void swiotlb_set_max_segment(unsigned int);



#endif /* __LINUX_SWIOTLB_H */

lib/swiotlb.c

+26 −0
Original line number Diff line number Diff line
@@ -82,6 +82,12 @@ static phys_addr_t io_tlb_overflow_buffer; 
static unsigned int *io_tlb_list;

static unsigned int io_tlb_index;



/*

 * Max segment that we can provide which (if pages are contingous) will

 * not be bounced (unless SWIOTLB_FORCE is set).

 */

unsigned int max_segment;



/*

 * We need to save away the original address corresponding to a mapped entry

 * for the sync operations.
@@ -124,6 +130,20 @@ unsigned long swiotlb_nr_tbl(void) 
}

EXPORT_SYMBOL_GPL(swiotlb_nr_tbl);



unsigned int swiotlb_max_segment(void)

{

	return max_segment;

}

EXPORT_SYMBOL_GPL(swiotlb_max_segment);



void swiotlb_set_max_segment(unsigned int val)

{

	if (swiotlb_force == SWIOTLB_FORCE)

		max_segment = 1;

	else

		max_segment = rounddown(val, PAGE_SIZE);

}



/* default to 64MB */

#define IO_TLB_DEFAULT_SIZE (64UL<<20)

unsigned long swiotlb_size_or_default(void)
@@ -205,6 +225,7 @@ int __init swiotlb_init_with_tbl(char *tlb, unsigned long nslabs, int verbose) 
	if (verbose)

		swiotlb_print_info();



	swiotlb_set_max_segment(io_tlb_nslabs << IO_TLB_SHIFT);

	return 0;

}
@@ -283,6 +304,7 @@ swiotlb_late_init_with_default_size(size_t default_size) 
	rc = swiotlb_late_init_with_tbl(vstart, io_tlb_nslabs);

	if (rc)

		free_pages((unsigned long)vstart, order);



	return rc;

}
@@ -337,6 +359,8 @@ swiotlb_late_init_with_tbl(char *tlb, unsigned long nslabs) 


	late_alloc = 1;



	swiotlb_set_max_segment(io_tlb_nslabs << IO_TLB_SHIFT);



	return 0;



cleanup4:
@@ -351,6 +375,7 @@ cleanup2: 
	io_tlb_end = 0;

	io_tlb_start = 0;

	io_tlb_nslabs = 0;

	max_segment = 0;

	return -ENOMEM;

}
@@ -379,6 +404,7 @@ void __init swiotlb_free(void) 
				   PAGE_ALIGN(io_tlb_nslabs << IO_TLB_SHIFT));

	}

	io_tlb_nslabs = 0;

	max_segment = 0;

}



int is_swiotlb_buffer(phys_addr_t paddr)

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