[PATCH 09/15] swiotlb: make the swiotlb_init interface more useful

Michael Kelley (LINUX) mikelley at microsoft.com
Mon Apr 4 10:00:34 PDT 2022


From: Christoph Hellwig <hch at lst.de> Sent: Sunday, April 3, 2022 10:06 PM
> 
> Pass a bool to pass if swiotlb needs to be enabled based on the

Wording problems.  I'm not sure what you meant to say.

> addressing needs and replace the verbose argument with a set of
> flags, including one to force enable bounce buffering.
> 
> Note that this patch removes the possibility to force xen-swiotlb
> use using swiotlb=force on the command line on x86 (arm and arm64
> never supported that), but this interface will be restored shortly.
> 
> Signed-off-by: Christoph Hellwig <hch at lst.de>
> ---
>  arch/arm/mm/init.c                     |  6 +----
>  arch/arm64/mm/init.c                   |  6 +----
>  arch/ia64/mm/init.c                    |  4 +--
>  arch/mips/cavium-octeon/dma-octeon.c   |  2 +-
>  arch/mips/loongson64/dma.c             |  2 +-
>  arch/mips/sibyte/common/dma.c          |  2 +-
>  arch/powerpc/mm/mem.c                  |  3 ++-
>  arch/powerpc/platforms/pseries/setup.c |  3 ---
>  arch/riscv/mm/init.c                   |  8 +-----
>  arch/s390/mm/init.c                    |  3 +--
>  arch/x86/kernel/pci-dma.c              | 15 ++++++-----
>  drivers/xen/swiotlb-xen.c              |  4 +--
>  include/linux/swiotlb.h                | 15 ++++++-----
>  include/trace/events/swiotlb.h         | 29 ++++++++-------------
>  kernel/dma/swiotlb.c                   | 35 ++++++++++++++------------
>  15 files changed, 55 insertions(+), 82 deletions(-)
> 
> diff --git a/arch/arm/mm/init.c b/arch/arm/mm/init.c
> index fe249ea919083..ce64bdb55a16b 100644
> --- a/arch/arm/mm/init.c
> +++ b/arch/arm/mm/init.c
> @@ -271,11 +271,7 @@ static void __init free_highpages(void)
>  void __init mem_init(void)
>  {
>  #ifdef CONFIG_ARM_LPAE
> -	if (swiotlb_force == SWIOTLB_FORCE ||
> -	    max_pfn > arm_dma_pfn_limit)
> -		swiotlb_init(1);
> -	else
> -		swiotlb_force = SWIOTLB_NO_FORCE;
> +	swiotlb_init(max_pfn > arm_dma_pfn_limit, SWIOTLB_VERBOSE);
>  #endif
> 
>  	set_max_mapnr(pfn_to_page(max_pfn) - mem_map);
> diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c
> index 8ac25f19084e8..7b6ea4d6733d6 100644
> --- a/arch/arm64/mm/init.c
> +++ b/arch/arm64/mm/init.c
> @@ -398,11 +398,7 @@ void __init bootmem_init(void)
>   */
>  void __init mem_init(void)
>  {
> -	if (swiotlb_force == SWIOTLB_FORCE ||
> -	    max_pfn > PFN_DOWN(arm64_dma_phys_limit))
> -		swiotlb_init(1);
> -	else if (!xen_swiotlb_detect())
> -		swiotlb_force = SWIOTLB_NO_FORCE;
> +	swiotlb_init(max_pfn > PFN_DOWN(arm64_dma_phys_limit),
> SWIOTLB_VERBOSE);
> 
>  	/* this will put all unused low memory onto the freelists */
>  	memblock_free_all();
> diff --git a/arch/ia64/mm/init.c b/arch/ia64/mm/init.c
> index 5d165607bf354..3c3e15b22608f 100644
> --- a/arch/ia64/mm/init.c
> +++ b/arch/ia64/mm/init.c
> @@ -437,9 +437,7 @@ mem_init (void)
>  		if (iommu_detected)
>  			break;
>  #endif
> -#ifdef CONFIG_SWIOTLB
> -		swiotlb_init(1);
> -#endif
> +		swiotlb_init(true, SWIOTLB_VERBOSE);
>  	} while (0);
> 
>  #ifdef CONFIG_FLATMEM
> diff --git a/arch/mips/cavium-octeon/dma-octeon.c b/arch/mips/cavium-octeon/dma-
> octeon.c
> index fb7547e217263..9fbba6a8fa4c5 100644
> --- a/arch/mips/cavium-octeon/dma-octeon.c
> +++ b/arch/mips/cavium-octeon/dma-octeon.c
> @@ -235,5 +235,5 @@ void __init plat_swiotlb_setup(void)
>  #endif
> 
>  	swiotlb_adjust_size(swiotlbsize);
> -	swiotlb_init(1);
> +	swiotlb_init(true, SWIOTLB_VERBOSE);
>  }
> diff --git a/arch/mips/loongson64/dma.c b/arch/mips/loongson64/dma.c
> index 364f2f27c8723..8220a1bc0db64 100644
> --- a/arch/mips/loongson64/dma.c
> +++ b/arch/mips/loongson64/dma.c
> @@ -24,5 +24,5 @@ phys_addr_t dma_to_phys(struct device *dev, dma_addr_t
> daddr)
> 
>  void __init plat_swiotlb_setup(void)
>  {
> -	swiotlb_init(1);
> +	swiotlb_init(true, SWIOTLB_VERBOSE);
>  }
> diff --git a/arch/mips/sibyte/common/dma.c b/arch/mips/sibyte/common/dma.c
> index eb47a94f3583e..c5c2c782aff68 100644
> --- a/arch/mips/sibyte/common/dma.c
> +++ b/arch/mips/sibyte/common/dma.c
> @@ -10,5 +10,5 @@
> 
>  void __init plat_swiotlb_setup(void)
>  {
> -	swiotlb_init(1);
> +	swiotlb_init(true, SWIOTLB_VERBOSE);
>  }
> diff --git a/arch/powerpc/mm/mem.c b/arch/powerpc/mm/mem.c
> index 8e301cd8925b2..e1519e2edc656 100644
> --- a/arch/powerpc/mm/mem.c
> +++ b/arch/powerpc/mm/mem.c
> @@ -17,6 +17,7 @@
>  #include <linux/suspend.h>
>  #include <linux/dma-direct.h>
> 
> +#include <asm/swiotlb.h>
>  #include <asm/machdep.h>
>  #include <asm/rtas.h>
>  #include <asm/kasan.h>
> @@ -251,7 +252,7 @@ void __init mem_init(void)
>  	if (is_secure_guest())
>  		svm_swiotlb_init();
>  	else
> -		swiotlb_init(0);
> +		swiotlb_init(ppc_swiotlb_enable, 0);
>  #endif
> 
>  	high_memory = (void *) __va(max_low_pfn * PAGE_SIZE);
> diff --git a/arch/powerpc/platforms/pseries/setup.c
> b/arch/powerpc/platforms/pseries/setup.c
> index 069d7b3bb142e..c6e06d91b6602 100644
> --- a/arch/powerpc/platforms/pseries/setup.c
> +++ b/arch/powerpc/platforms/pseries/setup.c
> @@ -838,9 +838,6 @@ static void __init pSeries_setup_arch(void)
>  	}
> 
>  	ppc_md.pcibios_root_bridge_prepare = pseries_root_bridge_prepare;
> -
> -	if (swiotlb_force == SWIOTLB_FORCE)
> -		ppc_swiotlb_enable = 1;
>  }
> 
>  static void pseries_panic(char *str)
> diff --git a/arch/riscv/mm/init.c b/arch/riscv/mm/init.c
> index 9535bea8688c0..181ffd322eafa 100644
> --- a/arch/riscv/mm/init.c
> +++ b/arch/riscv/mm/init.c
> @@ -120,13 +120,7 @@ void __init mem_init(void)
>  	BUG_ON(!mem_map);
>  #endif /* CONFIG_FLATMEM */
> 
> -#ifdef CONFIG_SWIOTLB
> -	if (swiotlb_force == SWIOTLB_FORCE ||
> -	    max_pfn > PFN_DOWN(dma32_phys_limit))
> -		swiotlb_init(1);
> -	else
> -		swiotlb_force = SWIOTLB_NO_FORCE;
> -#endif
> +	swiotlb_init(max_pfn > PFN_DOWN(dma32_phys_limit), SWIOTLB_VERBOSE);
>  	memblock_free_all();
> 
>  	print_vm_layout();
> diff --git a/arch/s390/mm/init.c b/arch/s390/mm/init.c
> index 86ffd0d51fd59..6fb6bf64326f9 100644
> --- a/arch/s390/mm/init.c
> +++ b/arch/s390/mm/init.c
> @@ -185,8 +185,7 @@ static void pv_init(void)
>  		return;
> 
>  	/* make sure bounce buffers are shared */
> -	swiotlb_force = SWIOTLB_FORCE;
> -	swiotlb_init(1);
> +	swiotlb_init(true, SWIOTLB_FORCE | SWIOTLB_VERBOSE);
>  	swiotlb_update_mem_attributes();
>  }
> 
> diff --git a/arch/x86/kernel/pci-dma.c b/arch/x86/kernel/pci-dma.c
> index 04140e20ef1a3..a705a199bf8a3 100644
> --- a/arch/x86/kernel/pci-dma.c
> +++ b/arch/x86/kernel/pci-dma.c
> @@ -39,6 +39,7 @@ int iommu_detected __read_mostly = 0;
> 
>  #ifdef CONFIG_SWIOTLB
>  bool x86_swiotlb_enable;
> +static unsigned int x86_swiotlb_flags;
> 
>  static void __init pci_swiotlb_detect(void)
>  {
> @@ -58,16 +59,16 @@ static void __init pci_swiotlb_detect(void)
>  	 * bounce buffers as the hypervisor can't access arbitrary VM memory
>  	 * that is not explicitly shared with it.
>  	 */
> -	if (cc_platform_has(CC_ATTR_GUEST_MEM_ENCRYPT))
> -		swiotlb_force = SWIOTLB_FORCE;
> -
> -	if (swiotlb_force == SWIOTLB_FORCE)
> +	if (cc_platform_has(CC_ATTR_GUEST_MEM_ENCRYPT)) {
>  		x86_swiotlb_enable = true;
> +		x86_swiotlb_flags |= SWIOTLB_FORCE;
> +	}
>  }
>  #else
>  static inline void __init pci_swiotlb_detect(void)
>  {
>  }
> +#define x86_swiotlb_flags 0
>  #endif /* CONFIG_SWIOTLB */
> 
>  #ifdef CONFIG_SWIOTLB_XEN
> @@ -75,8 +76,7 @@ static bool xen_swiotlb;
> 
>  static void __init pci_xen_swiotlb_init(void)
>  {
> -	if (!xen_initial_domain() && !x86_swiotlb_enable &&
> -	    swiotlb_force != SWIOTLB_FORCE)
> +	if (!xen_initial_domain() && !x86_swiotlb_enable)
>  		return;
>  	x86_swiotlb_enable = true;
>  	xen_swiotlb = true;
> @@ -120,8 +120,7 @@ void __init pci_iommu_alloc(void)
>  	gart_iommu_hole_init();
>  	amd_iommu_detect();
>  	detect_intel_iommu();
> -	if (x86_swiotlb_enable)
> -		swiotlb_init(0);
> +	swiotlb_init(x86_swiotlb_enable, x86_swiotlb_flags);
>  }
> 
>  /*
> diff --git a/drivers/xen/swiotlb-xen.c b/drivers/xen/swiotlb-xen.c
> index 485cd06ed39e7..c2da3eb4826e8 100644
> --- a/drivers/xen/swiotlb-xen.c
> +++ b/drivers/xen/swiotlb-xen.c
> @@ -251,7 +251,7 @@ void __init xen_swiotlb_init_early(void)
>  		panic("%s (rc:%d)", xen_swiotlb_error(XEN_SWIOTLB_EFIXUP), rc);
>  	}
> 
> -	if (swiotlb_init_with_tbl(start, nslabs, true))
> +	if (swiotlb_init_with_tbl(start, nslabs, SWIOTLB_VERBOSE))
>  		panic("Cannot allocate SWIOTLB buffer");
>  }
>  #endif /* CONFIG_X86 */
> @@ -376,7 +376,7 @@ static dma_addr_t xen_swiotlb_map_page(struct device *dev,
> struct page *page,
>  	/*
>  	 * Oh well, have to allocate and map a bounce buffer.
>  	 */
> -	trace_swiotlb_bounced(dev, dev_addr, size, swiotlb_force);
> +	trace_swiotlb_bounced(dev, dev_addr, size);
> 
>  	map = swiotlb_tbl_map_single(dev, phys, size, size, 0, dir, attrs);
>  	if (map == (phys_addr_t)DMA_MAPPING_ERROR)
> diff --git a/include/linux/swiotlb.h b/include/linux/swiotlb.h
> index b48b26bfa0edb..ae0407173e845 100644
> --- a/include/linux/swiotlb.h
> +++ b/include/linux/swiotlb.h
> @@ -13,11 +13,8 @@ struct device;
>  struct page;
>  struct scatterlist;
> 
> -enum swiotlb_force {
> -	SWIOTLB_NORMAL,		/* Default - depending on HW DMA mask etc.
> */
> -	SWIOTLB_FORCE,		/* swiotlb=force */
> -	SWIOTLB_NO_FORCE,	/* swiotlb=noforce */
> -};
> +#define SWIOTLB_VERBOSE	(1 << 0) /* verbose initialization */
> +#define SWIOTLB_FORCE	(1 << 1) /* force bounce buffering */
> 
>  /*
>   * Maximum allowable number of contiguous slabs to map,
> @@ -36,8 +33,7 @@ enum swiotlb_force {
>  /* default to 64MB */
>  #define IO_TLB_DEFAULT_SIZE (64UL<<20)
> 
> -extern void swiotlb_init(int verbose);
> -int swiotlb_init_with_tbl(char *tlb, unsigned long nslabs, int verbose);
> +int swiotlb_init_with_tbl(char *tlb, unsigned long nslabs, unsigned int flags);
>  unsigned long swiotlb_size_or_default(void);
>  extern int swiotlb_late_init_with_tbl(char *tlb, unsigned long nslabs);
>  int swiotlb_init_late(size_t size);
> @@ -126,13 +122,16 @@ static inline bool is_swiotlb_force_bounce(struct device
> *dev)
>  	return mem && mem->force_bounce;
>  }
> 
> +void swiotlb_init(bool addressing_limited, unsigned int flags);
>  void __init swiotlb_exit(void);
>  unsigned int swiotlb_max_segment(void);
>  size_t swiotlb_max_mapping_size(struct device *dev);
>  bool is_swiotlb_active(struct device *dev);
>  void __init swiotlb_adjust_size(unsigned long size);
>  #else
> -#define swiotlb_force SWIOTLB_NO_FORCE
> +static inline void swiotlb_init(bool addressing_limited, unsigned int flags)
> +{
> +}
>  static inline bool is_swiotlb_buffer(struct device *dev, phys_addr_t paddr)
>  {
>  	return false;
> diff --git a/include/trace/events/swiotlb.h b/include/trace/events/swiotlb.h
> index 705be43b71ab0..da05c9ebd224a 100644
> --- a/include/trace/events/swiotlb.h
> +++ b/include/trace/events/swiotlb.h
> @@ -8,20 +8,15 @@
>  #include <linux/tracepoint.h>
> 
>  TRACE_EVENT(swiotlb_bounced,
> -
> -	TP_PROTO(struct device *dev,
> -		 dma_addr_t dev_addr,
> -		 size_t size,
> -		 enum swiotlb_force swiotlb_force),
> -
> -	TP_ARGS(dev, dev_addr, size, swiotlb_force),
> +	TP_PROTO(struct device *dev, dma_addr_t dev_addr, size_t size),
> +	TP_ARGS(dev, dev_addr, size),
> 
>  	TP_STRUCT__entry(
> -		__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	)
> +		__string(dev_name, dev_name(dev))
> +		__field(u64, dma_mask)
> +		__field(dma_addr_t, dev_addr)
> +		__field(size_t, size)
> +		__field(bool, force)
>  	),
> 
>  	TP_fast_assign(
> @@ -29,19 +24,15 @@ TRACE_EVENT(swiotlb_bounced,
>  		__entry->dma_mask = (dev->dma_mask ? *dev->dma_mask : 0);
>  		__entry->dev_addr = dev_addr;
>  		__entry->size = size;
> -		__entry->swiotlb_force = swiotlb_force;
> +		__entry->force = is_swiotlb_force_bounce(dev);
>  	),
> 
> -	TP_printk("dev_name: %s dma_mask=%llx dev_addr=%llx "
> -		"size=%zu %s",
> +	TP_printk("dev_name: %s dma_mask=%llx dev_addr=%llx size=%zu %s",
>  		__get_str(dev_name),
>  		__entry->dma_mask,
>  		(unsigned long long)__entry->dev_addr,
>  		__entry->size,
> -		__print_symbolic(__entry->swiotlb_force,
> -			{ SWIOTLB_NORMAL,	"NORMAL" },
> -			{ SWIOTLB_FORCE,	"FORCE" },
> -			{ SWIOTLB_NO_FORCE,	"NO_FORCE" }))
> +		__entry->force ? "FORCE" : "NORMAL")
>  );
> 
>  #endif /*  _TRACE_SWIOTLB_H */
> diff --git a/kernel/dma/swiotlb.c b/kernel/dma/swiotlb.c
> index 9a4fe6e48a074..86e877a96b828 100644
> --- a/kernel/dma/swiotlb.c
> +++ b/kernel/dma/swiotlb.c
> @@ -62,7 +62,8 @@
> 
>  #define INVALID_PHYS_ADDR (~(phys_addr_t)0)
> 
> -enum swiotlb_force swiotlb_force;
> +static bool swiotlb_force_bounce;
> +static bool swiotlb_force_disable;
> 
>  struct io_tlb_mem io_tlb_default_mem;
> 
> @@ -81,9 +82,9 @@ setup_io_tlb_npages(char *str)
>  	if (*str == ',')
>  		++str;
>  	if (!strcmp(str, "force"))
> -		swiotlb_force = SWIOTLB_FORCE;
> +		swiotlb_force_bounce = true;
>  	else if (!strcmp(str, "noforce"))
> -		swiotlb_force = SWIOTLB_NO_FORCE;
> +		swiotlb_force_disable = true;
> 
>  	return 0;
>  }
> @@ -202,7 +203,7 @@ static void swiotlb_init_io_tlb_mem(struct io_tlb_mem *mem,
> phys_addr_t start,
>  	mem->index = 0;
>  	mem->late_alloc = late_alloc;
> 
> -	if (swiotlb_force == SWIOTLB_FORCE)
> +	if (swiotlb_force_bounce)
>  		mem->force_bounce = true;
> 
>  	spin_lock_init(&mem->lock);
> @@ -224,12 +225,13 @@ static void swiotlb_init_io_tlb_mem(struct io_tlb_mem
> *mem, phys_addr_t start,
>  	return;
>  }
> 
> -int __init swiotlb_init_with_tbl(char *tlb, unsigned long nslabs, int verbose)
> +int __init swiotlb_init_with_tbl(char *tlb, unsigned long nslabs,
> +		unsigned int flags)
>  {
>  	struct io_tlb_mem *mem = &io_tlb_default_mem;
>  	size_t alloc_size;
> 
> -	if (swiotlb_force == SWIOTLB_NO_FORCE)
> +	if (swiotlb_force_disable)
>  		return 0;
> 
>  	/* protect against double initialization */
> @@ -243,8 +245,9 @@ int __init swiotlb_init_with_tbl(char *tlb, unsigned long nslabs,
> int verbose)
>  		      __func__, alloc_size, PAGE_SIZE);
> 
>  	swiotlb_init_io_tlb_mem(mem, __pa(tlb), nslabs, false);
> +	mem->force_bounce = flags & SWIOTLB_FORCE;
> 
> -	if (verbose)
> +	if (flags & SWIOTLB_VERBOSE)
>  		swiotlb_print_info();
>  	return 0;
>  }
> @@ -253,20 +256,21 @@ int __init swiotlb_init_with_tbl(char *tlb, unsigned long
> nslabs, int verbose)
>   * 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(int verbose)
> +void __init swiotlb_init(bool addressing_limit, unsigned int flags)
>  {
>  	size_t bytes = PAGE_ALIGN(default_nslabs << IO_TLB_SHIFT);
>  	void *tlb;
> 
> -	if (swiotlb_force == SWIOTLB_NO_FORCE)
> +	if (!addressing_limit && !swiotlb_force_bounce)
> +		return;
> +	if (swiotlb_force_disable)
>  		return;
> 
>  	/* Get IO TLB memory from the low pages */
>  	tlb = memblock_alloc_low(bytes, PAGE_SIZE);
>  	if (!tlb)
>  		goto fail;
> -	if (swiotlb_init_with_tbl(tlb, default_nslabs, verbose))
> +	if (swiotlb_init_with_tbl(tlb, default_nslabs, flags))
>  		goto fail_free_mem;
>  	return;
> 
> @@ -289,7 +293,7 @@ int swiotlb_init_late(size_t size)
>  	unsigned int order;
>  	int rc = 0;
> 
> -	if (swiotlb_force == SWIOTLB_NO_FORCE)
> +	if (swiotlb_force_disable)
>  		return 0;
> 
>  	/*
> @@ -328,7 +332,7 @@ swiotlb_late_init_with_tbl(char *tlb, unsigned long nslabs)
>  	struct io_tlb_mem *mem = &io_tlb_default_mem;
>  	unsigned long bytes = nslabs << IO_TLB_SHIFT;
> 
> -	if (swiotlb_force == SWIOTLB_NO_FORCE)
> +	if (swiotlb_force_disable)
>  		return 0;
> 
>  	/* protect against double initialization */
> @@ -353,7 +357,7 @@ void __init swiotlb_exit(void)
>  	unsigned long tbl_vaddr;
>  	size_t tbl_size, slots_size;
> 
> -	if (swiotlb_force == SWIOTLB_FORCE)
> +	if (swiotlb_force_bounce)
>  		return;
> 
>  	if (!mem->nslabs)
> @@ -704,8 +708,7 @@ dma_addr_t swiotlb_map(struct device *dev, phys_addr_t
> paddr, size_t size,
>  	phys_addr_t swiotlb_addr;
>  	dma_addr_t dma_addr;
> 
> -	trace_swiotlb_bounced(dev, phys_to_dma(dev, paddr), size,
> -			      swiotlb_force);
> +	trace_swiotlb_bounced(dev, phys_to_dma(dev, paddr), size);
> 
>  	swiotlb_addr = swiotlb_tbl_map_single(dev, paddr, size, size, 0, dir,
>  			attrs);
> --
> 2.30.2




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