Merge branch 'stable/for-linus-4.10' of git://git.kernel.org/pub/scm/linux/kernel/git/konrad/swiotlb

Pull swiotlb fixes from Konrad Rzeszutek Wilk:
 "This has one fix to make i915 work when using Xen SWIOTLB, and a
  feature from Geert to aid in debugging of devices that can't do DMA
  outside the 32-bit address space.

  The feature from Geert is on top of v4.10 merge window commit
  (specifically you pulling my previous branch), as his changes were
  dependent on the Documentation/ movement patches.

  I figured it would just easier than me trying than to cherry-pick the
  Documentation patches to satisfy git.

  The patches have been soaking since 12/20, albeit I updated the last
  patch due to linux-next catching an compiler error and adding an
  Tested-and-Reported-by tag"

* 'stable/for-linus-4.10' of git://git.kernel.org/pub/scm/linux/kernel/git/konrad/swiotlb:
  swiotlb: Export swiotlb_max_segment to users
  swiotlb: Add swiotlb=noforce debug option
  swiotlb: Convert swiotlb_force from int to enum
  x86, swiotlb: Simplify pci_swiotlb_detect_override()

10 files changed, 82 insertions, 34 deletions

diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index d1eec5ed1134..be7c0d9506b1 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -3821,10 +3821,11 @@
                         it if 0 is given (See Documentation/cgroup-v1/memory.txt)
 
         swiotlb=        [ARM,IA-64,PPC,MIPS,X86]
-                        Format: { <int> | force }
+                        Format: { <int> | force | noforce }
                         <int> -- 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/arch/arm64/mm/dma-mapping.c b/arch/arm64/mm/dma-mapping.c
index 290a84f3351f..e04082700bb1 100644
--- a/arch/arm64/mm/dma-mapping.c
+++ b/arch/arm64/mm/dma-mapping.c
@@ -524,7 +524,8 @@ EXPORT_SYMBOL(dummy_dma_ops);
 
 static int __init arm64_dma_init(void)
 {
-        if (swiotlb_force || max_pfn > (arm64_dma_phys_limit >> PAGE_SHIFT))
+        if (swiotlb_force == SWIOTLB_FORCE ||
+            max_pfn > (arm64_dma_phys_limit >> PAGE_SHIFT))
                 swiotlb = 1;
 
         return atomic_pool_init();
diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c
index 212c4d1e2f26..716d1226ba69 100644
--- a/arch/arm64/mm/init.c
+++ b/arch/arm64/mm/init.c
@@ -401,7 +401,8 @@ static void __init free_unused_memmap(void)
  */
 void __init mem_init(void)
 {
-        if (swiotlb_force || max_pfn > (arm64_dma_phys_limit >> PAGE_SHIFT))
+        if (swiotlb_force == SWIOTLB_FORCE ||
+            max_pfn > (arm64_dma_phys_limit >> PAGE_SHIFT))
                 swiotlb_init(1);
 
         set_max_mapnr(pfn_to_page(max_pfn) - mem_map);
diff --git a/arch/x86/kernel/pci-swiotlb.c b/arch/x86/kernel/pci-swiotlb.c
index b47edb8f5256..410efb2c7b80 100644
--- a/arch/x86/kernel/pci-swiotlb.c
+++ b/arch/x86/kernel/pci-swiotlb.c
@@ -68,12 +68,10 @@ static struct dma_map_ops swiotlb_dma_ops = {
  */
 int __init pci_swiotlb_detect_override(void)
 {
-        int use_swiotlb = swiotlb | swiotlb_force;
-
-        if (swiotlb_force)
+        if (swiotlb_force == SWIOTLB_FORCE)
                 swiotlb = 1;
 
-        return use_swiotlb;
+        return swiotlb;
 }
 IOMMU_INIT_FINISH(pci_swiotlb_detect_override,
                   pci_xen_swiotlb_detect,
diff --git a/arch/x86/xen/pci-swiotlb-xen.c b/arch/x86/xen/pci-swiotlb-xen.c
index a9fafb5c8738..a0b36a9d5df1 100644
--- a/arch/x86/xen/pci-swiotlb-xen.c
+++ b/arch/x86/xen/pci-swiotlb-xen.c
@@ -48,7 +48,7 @@ int __init pci_xen_swiotlb_detect(void)
          * activate this IOMMU. If running as PV privileged, activate it
          * irregardless.
          */
-        if ((xen_initial_domain() || swiotlb || swiotlb_force))
+        if (xen_initial_domain() || swiotlb || swiotlb_force == SWIOTLB_FORCE)
                 xen_swiotlb = 1;
 
         /* If we are running under Xen, we MUST disable the native SWIOTLB.
diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index 1e505d30b71e..3dd7fc662859 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -2306,15 +2306,6 @@ 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;
@@ -2362,7 +2353,7 @@ 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 478fb91e3df2..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--) {
@@ -392,7 +396,7 @@ 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 != 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. */
@@ -552,7 +556,7 @@ xen_swiotlb_map_sg_attrs(struct device *hwdev, struct scatterlist *sgl,
                 phys_addr_t paddr = sg_phys(sg);
                 dma_addr_t dev_addr = xen_phys_to_bus(paddr);
 
-                if (swiotlb_force ||
+                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)) {
diff --git a/include/linux/swiotlb.h b/include/linux/swiotlb.h
index 183f37c8a5e1..4ee479f2f355 100644
--- a/include/linux/swiotlb.h
+++ b/include/linux/swiotlb.h
@@ -9,7 +9,13 @@ 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 */
+        SWIOTLB_NO_FORCE,       /* swiotlb=noforce */
+};
+
+extern enum swiotlb_force swiotlb_force;
 
 /*
  * Maximum allowable number of contiguous slabs to map,
@@ -108,11 +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/include/trace/events/swiotlb.h b/include/trace/events/swiotlb.h
index 7ea4c5e7c448..288c0c54a2b4 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 +37,10 @@ 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" },
+                        { SWIOTLB_NO_FORCE,     "NO_FORCE" }))
 );
 
 #endif /*  _TRACE_SWIOTLB_H */
diff --git a/lib/swiotlb.c b/lib/swiotlb.c
index cb1b54ee8527..975b8fc4f1e1 100644
--- a/lib/swiotlb.c
+++ b/lib/swiotlb.c
@@ -53,7 +53,7 @@
  */
 #define IO_TLB_MIN_SLABS ((1<<20) >> IO_TLB_SHIFT)
 
-int swiotlb_force;
+enum swiotlb_force swiotlb_force;
 
 /*
  * Used to do a quick range check in swiotlb_tbl_unmap_single and
@@ -83,6 +83,12 @@ 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.
  */
@@ -106,8 +112,12 @@ setup_io_tlb_npages(char *str)
         }
         if (*str == ',')
                 ++str;
-        if (!strcmp(str, "force"))
-                swiotlb_force = 1;
+        if (!strcmp(str, "force")) {
+                swiotlb_force = SWIOTLB_FORCE;
+        } else if (!strcmp(str, "noforce")) {
+                swiotlb_force = SWIOTLB_NO_FORCE;
+                io_tlb_nslabs = 1;
+        }
 
         return 0;
 }
@@ -120,6 +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)
@@ -201,6 +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;
 }
 
@@ -279,6 +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;
 }
 
@@ -333,6 +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:
@@ -347,6 +375,7 @@ cleanup2:
         io_tlb_end = 0;
         io_tlb_start = 0;
         io_tlb_nslabs = 0;
+        max_segment = 0;
         return -ENOMEM;
 }
 
@@ -375,6 +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)
@@ -543,8 +573,15 @@ 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 +758,9 @@ 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.
@@ -763,7 +803,7 @@ dma_addr_t swiotlb_map_page(struct device *dev, struct page *page,
          * we can safely return the device addr and not worry about bounce
          * buffering it.
          */
-        if (dma_capable(dev, dev_addr, size) && !swiotlb_force)
+        if (dma_capable(dev, dev_addr, size) && swiotlb_force != SWIOTLB_FORCE)
                 return dev_addr;
 
         trace_swiotlb_bounced(dev, dev_addr, size, swiotlb_force);
@@ -904,7 +944,7 @@ swiotlb_map_sg_attrs(struct device *hwdev, struct scatterlist *sgl, int nelems,
                 phys_addr_t paddr = sg_phys(sg);
                 dma_addr_t dev_addr = phys_to_dma(hwdev, paddr);
 
-                if (swiotlb_force ||
+                if (swiotlb_force == SWIOTLB_FORCE ||
                     !dma_capable(hwdev, dev_addr, sg->length)) {
                         phys_addr_t map = map_single(hwdev, sg_phys(sg),
                                                      sg->length, dir, attrs);