From ae7871be189cb41184f1e05742b4a99e2c59774d Mon Sep 17 00:00:00 2001 From: Geert Uytterhoeven Date: Fri, 16 Dec 2016 14:28:41 +0100 Subject: swiotlb: Convert swiotlb_force from int to enum Convert the flag swiotlb_force from an int to an enum, to prepare for the advent of more possible values. Suggested-by: Konrad Rzeszutek Wilk Signed-off-by: Geert Uytterhoeven Signed-off-by: Konrad Rzeszutek Wilk --- include/linux/swiotlb.h | 7 ++++++- include/trace/events/swiotlb.h | 16 +++++++++------- 2 files changed, 15 insertions(+), 8 deletions(-) (limited to 'include') diff --git a/include/linux/swiotlb.h b/include/linux/swiotlb.h index 183f37c8a5e1..71d104e4c849 100644 --- a/include/linux/swiotlb.h +++ b/include/linux/swiotlb.h @@ -9,7 +9,12 @@ struct device; struct page; struct scatterlist; -extern int swiotlb_force; +enum swiotlb_force { + SWIOTLB_NORMAL, /* Default - depending on HW DMA mask etc. */ + SWIOTLB_FORCE, /* swiotlb=force */ +}; + +extern enum swiotlb_force swiotlb_force; /* * Maximum allowable number of contiguous slabs to map, diff --git a/include/trace/events/swiotlb.h b/include/trace/events/swiotlb.h index 7ea4c5e7c448..5e2e30a7efce 100644 --- a/include/trace/events/swiotlb.h +++ b/include/trace/events/swiotlb.h @@ -11,16 +11,16 @@ TRACE_EVENT(swiotlb_bounced, TP_PROTO(struct device *dev, dma_addr_t dev_addr, size_t size, - int swiotlb_force), + enum swiotlb_force swiotlb_force), TP_ARGS(dev, dev_addr, size, swiotlb_force), TP_STRUCT__entry( - __string( dev_name, dev_name(dev) ) - __field( u64, dma_mask ) - __field( dma_addr_t, dev_addr ) - __field( size_t, size ) - __field( int, swiotlb_force ) + __string( dev_name, dev_name(dev) ) + __field( u64, dma_mask ) + __field( dma_addr_t, dev_addr ) + __field( size_t, size ) + __field( enum swiotlb_force, swiotlb_force ) ), TP_fast_assign( @@ -37,7 +37,9 @@ TRACE_EVENT(swiotlb_bounced, __entry->dma_mask, (unsigned long long)__entry->dev_addr, __entry->size, - __entry->swiotlb_force ? "swiotlb_force" : "" ) + __print_symbolic(__entry->swiotlb_force, + { SWIOTLB_NORMAL, "NORMAL" }, + { SWIOTLB_FORCE, "FORCE" })) ); #endif /* _TRACE_SWIOTLB_H */ -- cgit v1.2.3-70-g09d2 From fff5d99225107f5f13fe4a9805adc2a1c4b5fb00 Mon Sep 17 00:00:00 2001 From: Geert Uytterhoeven Date: Fri, 16 Dec 2016 14:28:42 +0100 Subject: swiotlb: Add swiotlb=noforce debug option On architectures like arm64, swiotlb is tied intimately to the core architecture DMA support. In addition, ZONE_DMA cannot be disabled. To aid debugging and catch devices not supporting DMA to memory outside the 32-bit address space, add a kernel command line option "swiotlb=noforce", which disables the use of bounce buffers. If specified, trying to map memory that cannot be used with DMA will fail, and a rate-limited warning will be printed. Note that io_tlb_nslabs is set to 1, which is the minimal supported value. Signed-off-by: Geert Uytterhoeven Signed-off-by: Konrad Rzeszutek Wilk --- Documentation/admin-guide/kernel-parameters.txt | 3 ++- include/linux/swiotlb.h | 1 + include/trace/events/swiotlb.h | 3 ++- lib/swiotlb.c | 18 ++++++++++++++++-- 4 files changed, 21 insertions(+), 4 deletions(-) (limited to 'include') diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt index be2d6d0a03a4..7d5f4f4cecfa 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -3807,10 +3807,11 @@ it if 0 is given (See Documentation/cgroup-v1/memory.txt) swiotlb= [ARM,IA-64,PPC,MIPS,X86] - Format: { | force } + Format: { | force | noforce } -- Number of I/O TLB slabs force -- force using of bounce buffers even if they wouldn't be automatically used by the kernel + noforce -- Never use bounce buffers (for debugging) switches= [HW,M68k] diff --git a/include/linux/swiotlb.h b/include/linux/swiotlb.h index 71d104e4c849..d9c84a9cde3d 100644 --- a/include/linux/swiotlb.h +++ b/include/linux/swiotlb.h @@ -12,6 +12,7 @@ struct scatterlist; enum swiotlb_force { SWIOTLB_NORMAL, /* Default - depending on HW DMA mask etc. */ SWIOTLB_FORCE, /* swiotlb=force */ + SWIOTLB_NO_FORCE, /* swiotlb=noforce */ }; extern enum swiotlb_force swiotlb_force; diff --git a/include/trace/events/swiotlb.h b/include/trace/events/swiotlb.h index 5e2e30a7efce..288c0c54a2b4 100644 --- a/include/trace/events/swiotlb.h +++ b/include/trace/events/swiotlb.h @@ -39,7 +39,8 @@ TRACE_EVENT(swiotlb_bounced, __entry->size, __print_symbolic(__entry->swiotlb_force, { SWIOTLB_NORMAL, "NORMAL" }, - { SWIOTLB_FORCE, "FORCE" })) + { SWIOTLB_FORCE, "FORCE" }, + { SWIOTLB_NO_FORCE, "NO_FORCE" })) ); #endif /* _TRACE_SWIOTLB_H */ diff --git a/lib/swiotlb.c b/lib/swiotlb.c index a32dce6d5101..9def738af4f4 100644 --- a/lib/swiotlb.c +++ b/lib/swiotlb.c @@ -106,8 +106,12 @@ setup_io_tlb_npages(char *str) } if (*str == ',') ++str; - if (!strcmp(str, "force")) + if (!strcmp(str, "force")) { swiotlb_force = SWIOTLB_FORCE; + } else if (!strcmp(str, "noforce")) { + swiotlb_force = SWIOTLB_NO_FORCE; + io_tlb_nslabs = 1; + } return 0; } @@ -543,8 +547,15 @@ static phys_addr_t map_single(struct device *hwdev, phys_addr_t phys, size_t size, enum dma_data_direction dir, unsigned long attrs) { - dma_addr_t start_dma_addr = phys_to_dma(hwdev, io_tlb_start); + dma_addr_t start_dma_addr; + + if (swiotlb_force == SWIOTLB_NO_FORCE) { + dev_warn_ratelimited(hwdev, "Cannot do DMA to address %pa\n", + &phys); + return SWIOTLB_MAP_ERROR; + } + start_dma_addr = phys_to_dma(hwdev, io_tlb_start); return swiotlb_tbl_map_single(hwdev, start_dma_addr, phys, size, dir, attrs); } @@ -721,6 +732,9 @@ static void swiotlb_full(struct device *dev, size_t size, enum dma_data_direction dir, int do_panic) { + if (swiotlb_force == SWIOTLB_NO_FORCE) + return; + /* * Ran out of IOMMU space for this operation. This is very bad. * Unfortunately the drivers cannot handle this operation properly. -- cgit v1.2.3-70-g09d2 From 7453c549f5f6485c0d79cad7844870dcc7d1b34d Mon Sep 17 00:00:00 2001 From: Konrad Rzeszutek Wilk Date: Tue, 20 Dec 2016 10:02:02 -0500 Subject: 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: Konrad Rzeszutek Wilk Reported-and-Tested-by: Juergen Gross --- drivers/gpu/drm/i915/i915_gem.c | 11 +---------- drivers/xen/swiotlb-xen.c | 4 ++++ include/linux/swiotlb.h | 3 +++ lib/swiotlb.c | 26 ++++++++++++++++++++++++++ 4 files changed, 34 insertions(+), 10 deletions(-) (limited to 'include') diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c index d0dcaf35b429..115fa399608c 100644 --- a/drivers/gpu/drm/i915/i915_gem.c +++ b/drivers/gpu/drm/i915/i915_gem.c @@ -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); diff --git a/drivers/xen/swiotlb-xen.c b/drivers/xen/swiotlb-xen.c index aba12009422e..f905d6eeb048 100644 --- a/drivers/xen/swiotlb-xen.c +++ b/drivers/xen/swiotlb-xen.c @@ -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--) { diff --git a/include/linux/swiotlb.h b/include/linux/swiotlb.h index d9c84a9cde3d..4ee479f2f355 100644 --- a/include/linux/swiotlb.h +++ b/include/linux/swiotlb.h @@ -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 */ diff --git a/lib/swiotlb.c b/lib/swiotlb.c index 9def738af4f4..975b8fc4f1e1 100644 --- a/lib/swiotlb.c +++ b/lib/swiotlb.c @@ -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) -- cgit v1.2.3-70-g09d2