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Re: [PATCH v4 1/8] swiotlb: make io_tlb_default_mem local to swiotlb.c



Hi Petr,

On 13/7/23 17:23, Petr Tesarik wrote:
From: Petr Tesarik <petr.tesarik.ext@xxxxxxxxxx>

SWIOTLB implementation details should not be exposed to the rest of the
kernel. This will allow to make changes to the implementation without
modifying non-swiotlb code.

To avoid breaking existing users, provide helper functions for the few
required fields.

As a bonus, using a helper function to initialize struct device allows to
get rid of an #ifdef in driver core.

Signed-off-by: Petr Tesarik <petr.tesarik.ext@xxxxxxxxxx>
---
  arch/arm/xen/mm.c          |  2 +-
  arch/mips/pci/pci-octeon.c |  2 +-
  arch/x86/kernel/pci-dma.c  |  2 +-
  drivers/base/core.c        |  4 +---
  drivers/xen/swiotlb-xen.c  |  2 +-
  include/linux/swiotlb.h    | 25 +++++++++++++++++++++++-
  kernel/dma/swiotlb.c       | 39 +++++++++++++++++++++++++++++++++++++-
  7 files changed, 67 insertions(+), 9 deletions(-)


diff --git a/include/linux/swiotlb.h b/include/linux/swiotlb.h
index 4e52cd5e0bdc..07216af59e93 100644
--- a/include/linux/swiotlb.h
+++ b/include/linux/swiotlb.h
@@ -110,7 +110,6 @@ struct io_tlb_mem {
        atomic_long_t used_hiwater;
  #endif
  };
-extern struct io_tlb_mem io_tlb_default_mem;
static inline bool is_swiotlb_buffer(struct device *dev, phys_addr_t paddr)
  {
@@ -128,13 +127,22 @@ static inline bool is_swiotlb_force_bounce(struct device 
*dev)
void swiotlb_init(bool addressing_limited, unsigned int flags);
  void __init swiotlb_exit(void);
+void swiotlb_dev_init(struct device *dev);
  size_t swiotlb_max_mapping_size(struct device *dev);
+bool is_swiotlb_allocated(void);
  bool is_swiotlb_active(struct device *dev);
  void __init swiotlb_adjust_size(unsigned long size);
+phys_addr_t default_swiotlb_start(void);
+phys_addr_t default_swiotlb_limit(void);

Usually we use start/end, base/limit, low[est]/high[est] tuples.

Possibly clearer to rename, regardless:
Reviewed-by: Philippe Mathieu-Daudé <philmd@xxxxxxxxxx>

diff --git a/kernel/dma/swiotlb.c b/kernel/dma/swiotlb.c
index 2b83e3ad9dca..873b077d7e37 100644
--- a/kernel/dma/swiotlb.c
+++ b/kernel/dma/swiotlb.c


@@ -958,6 +975,26 @@ bool is_swiotlb_active(struct device *dev)
  }
  EXPORT_SYMBOL_GPL(is_swiotlb_active);
+/**
+ * default_swiotlb_start() - get the start of the default SWIOTLB
+ *
+ * Get the lowest physical address used by the default software IO TLB pool.
+ */
+phys_addr_t default_swiotlb_start(void)
+{
+       return io_tlb_default_mem.start;
+}
+
+/**
+ * default_swiotlb_limit() - get the highest address in the default SWIOTLB
+ *
+ * Get the highest physical address used by the default software IO TLB pool.

(note you describe lowest/highest).

+ */
+phys_addr_t default_swiotlb_limit(void)
+{
+       return io_tlb_default_mem.end - 1;
+}
+
  #ifdef CONFIG_DEBUG_FS
static int io_tlb_used_get(void *data, u64 *val)




 


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