Re: [Xen-devel] [PATCH v3] modify the IO_TLB_SEGSIZE and IO_TLB_DEFAULT_SIZE configurable as flexible requirement about SW-IOMMU.

["Wang, Xiaoming" <xiaoming.wang@xxxxxxxxx>]

Dear Wilk

> -----Original Message-----
> From: Konrad Rzeszutek Wilk [mailto:konrad.wilk@xxxxxxxxxx]
> Sent: Tuesday, February 17, 2015 6:13 AM
> To: Wang, Xiaoming
> Cc: ralf@xxxxxxxxxxxxxx; boris.ostrovsky@xxxxxxxxxx;
> david.vrabel@xxxxxxxxxx; linux-mips@xxxxxxxxxxxxxx; linux-
> kernel@xxxxxxxxxxxxxxx; xen-devel@xxxxxxxxxxxxxxxxxxxx; akpm@linux-
> foundation.org; linux@xxxxxxxxxxx; lauraa@xxxxxxxxxxxxxx;
> heiko.carstens@xxxxxxxxxx; d.kasatkin@xxxxxxxxxxx;
> takahiro.akashi@xxxxxxxxxx; chris@xxxxxxxxxxxxxxxxxx; pebolle@xxxxxxxxxx; Liu,
> Chuansheng; Zhang, Dongxing
> Subject: Re: [PATCH v3] modify the IO_TLB_SEGSIZE and
> IO_TLB_DEFAULT_SIZE configurable as flexible requirement about SW-
> IOMMU.
> 
> On Mon, Feb 16, 2015 at 10:38:18AM +0800, Wang Xiaoming wrote:
> > The maximum of SW-IOMMU is limited to 2^11*128 = 256K.
> > And the maximum of IO_TLB_DEFAULT_SIZE is limited to (64UL<<20) 64M.
> > While in different platform and different requirement this seems improper.
> > So modifing the IO_TLB_SEGSIZE to io_tlb_segsize and
> > IO_TLB_DEFAULT_SIZE to io_tlb_default_size which can configure by
> BOARD_KERNEL_CMDLINE in BoardConfig.mk.
> 
> Thsi patch does not have anything in BoardConfig.mk. Perhaps remove this.
> 
> Got a couple of things below:
> > This can meet different requirement.
> >
> > Signed-off-by: Chuansheng Liu <chuansheng.liu@xxxxxxxxx>
> > Signed-off-by: Zhang Dongxing <dongxing.zhang@xxxxxxxxx>
> > Signed-off-by: Wang Xiaoming <xiaoming.wang@xxxxxxxxx>
> > ---
> > patch v1 make this change at Kconfig
> > which needs to edit the .config manually.
> > https://lkml.org/lkml/2015/1/25/571
> >
> > patch v2 only change IO_TLB_SEGSIZE configurable
> > https://lkml.org/lkml/2015/2/5/812
> >
> >  arch/mips/cavium-octeon/dma-octeon.c |    2 +-
> >  arch/mips/netlogic/common/nlm-dma.c  |    2 +-
> >  drivers/xen/swiotlb-xen.c            |    6 ++--
> >  include/linux/swiotlb.h              |    8 +----
> >  lib/swiotlb.c                        |   58 
> > +++++++++++++++++++++++++---------
> >  5 files changed, 49 insertions(+), 27 deletions(-)
> >
> > diff --git a/arch/mips/cavium-octeon/dma-octeon.c
> > b/arch/mips/cavium-octeon/dma-octeon.c
> > index 3778655..a521af6 100644
> > --- a/arch/mips/cavium-octeon/dma-octeon.c
> > +++ b/arch/mips/cavium-octeon/dma-octeon.c
> > @@ -312,7 +312,7 @@ void __init plat_swiotlb_setup(void)
> >             swiotlbsize = 64 * (1<<20);
> >  #endif
> >     swiotlb_nslabs = swiotlbsize >> IO_TLB_SHIFT;
> > -   swiotlb_nslabs = ALIGN(swiotlb_nslabs, IO_TLB_SEGSIZE);
> > +   swiotlb_nslabs = ALIGN(swiotlb_nslabs, io_tlb_segsize);
> >     swiotlbsize = swiotlb_nslabs << IO_TLB_SHIFT;
> >
> >     octeon_swiotlb = alloc_bootmem_low_pages(swiotlbsize);
> > diff --git a/arch/mips/netlogic/common/nlm-dma.c
> > b/arch/mips/netlogic/common/nlm-dma.c
> > index f3d4ae8..eeffa8f 100644
> > --- a/arch/mips/netlogic/common/nlm-dma.c
> > +++ b/arch/mips/netlogic/common/nlm-dma.c
> > @@ -99,7 +99,7 @@ void __init plat_swiotlb_setup(void)
> >
> >     swiotlbsize = 1 << 20; /* 1 MB for now */
> >     swiotlb_nslabs = swiotlbsize >> IO_TLB_SHIFT;
> > -   swiotlb_nslabs = ALIGN(swiotlb_nslabs, IO_TLB_SEGSIZE);
> > +   swiotlb_nslabs = ALIGN(swiotlb_nslabs, io_tlb_segsize);
> >     swiotlbsize = swiotlb_nslabs << IO_TLB_SHIFT;
> >
> >     nlm_swiotlb = alloc_bootmem_low_pages(swiotlbsize);
> > diff --git a/drivers/xen/swiotlb-xen.c b/drivers/xen/swiotlb-xen.c
> > index 810ad41..3b3e9fe 100644
> > --- a/drivers/xen/swiotlb-xen.c
> > +++ b/drivers/xen/swiotlb-xen.c
> > @@ -164,11 +164,11 @@ xen_swiotlb_fixup(void *buf, size_t size,
> unsigned long nslabs)
> >     dma_addr_t dma_handle;
> >     phys_addr_t p = virt_to_phys(buf);
> >
> > -   dma_bits = get_order(IO_TLB_SEGSIZE << IO_TLB_SHIFT) +
> PAGE_SHIFT;
> > +   dma_bits = get_order(io_tlb_segsize << IO_TLB_SHIFT) + PAGE_SHIFT;
> >
> >     i = 0;
> >     do {
> > -           int slabs = min(nslabs - i, (unsigned long)IO_TLB_SEGSIZE);
> > +           int slabs = min(nslabs - i, (unsigned long)io_tlb_segsize);
> >
> >             do {
> >                     rc = xen_create_contiguous_region( @@ -187,7
> +187,7 @@ static
> > unsigned long xen_set_nslabs(unsigned long nr_tbl)  {
> >     if (!nr_tbl) {
> >             xen_io_tlb_nslabs = (64 * 1024 * 1024 >> IO_TLB_SHIFT);
> > -           xen_io_tlb_nslabs = ALIGN(xen_io_tlb_nslabs,
> IO_TLB_SEGSIZE);
> > +           xen_io_tlb_nslabs = ALIGN(xen_io_tlb_nslabs, io_tlb_segsize);
> >     } else
> >             xen_io_tlb_nslabs = nr_tbl;
> >
> > diff --git a/include/linux/swiotlb.h b/include/linux/swiotlb.h index
> > e7a018e..13506db 100644
> > --- a/include/linux/swiotlb.h
> > +++ b/include/linux/swiotlb.h
> > @@ -8,13 +8,7 @@ struct dma_attrs;
> >  struct scatterlist;
> >
> >  extern int swiotlb_force;
> > -
> > -/*
> > - * Maximum allowable number of contiguous slabs to map,
> > - * must be a power of 2.  What is the appropriate value ?
> > - * The complexity of {map,unmap}_single is linearly dependent on this
> value.
> > - */
> > -#define IO_TLB_SEGSIZE     128
> > +extern int io_tlb_segsize;
> >
> >  /*
> >   * log of the size of each IO TLB slab.  The number of slabs is
> > command line diff --git a/lib/swiotlb.c b/lib/swiotlb.c index
> > 4abda07..1db5fc8 100644
> > --- a/lib/swiotlb.c
> > +++ b/lib/swiotlb.c
> > @@ -56,6 +56,15 @@
> >  int swiotlb_force;
> >
> >  /*
> > + * Maximum allowable number of contiguous slabs to map,
> > + * must be a power of 2.  What is the appropriate value ?
> > + * define io_tlb_segsize as a parameter
> > + * which can be changed dynamically in config file for special usage.
> > + * The complexity of {map,unmap}_single is linearly dependent on this
> value.
> > + */
> > +int io_tlb_segsize = 128;
> > +
> > +/*
> >   * Used to do a quick range check in swiotlb_tbl_unmap_single and
> >   * swiotlb_tbl_sync_single_*, to see if the memory was in fact allocated by
> this
> >   * API.
> > @@ -97,12 +106,20 @@ static DEFINE_SPINLOCK(io_tlb_lock);  static int
> > late_alloc;
> >
> >  static int __init
> > +setup_io_tlb_segsize(char *str)
> > +{
> > +   get_option(&str, &io_tlb_segsize);
> > +   return 0;
> > +}
> > +__setup("io_tlb_segsize=", setup_io_tlb_segsize);
> 
> This should be folded in swiotlb=XYZ parsing please.
> 
I am not very clear about this comment.
1,      Do you mean it should use early_param instead of __setup?
As I known early_param  can't help to assign the parameter that we changed at
kernel cmdline  because we have the default value here.
int io_tlb_segsize = 128;
unsigned long io_tlb_default_size = (64UL<<20);
2,      Or do you mean use iotlbsegsize instead of io_tlb_segsize?

> Also you will need to update the Documentaiton/kernel-parameters.txt file.
> 
> > +
> > +static int __init
> >  setup_io_tlb_npages(char *str)
> >  {
> >     if (isdigit(*str)) {
> >             io_tlb_nslabs = simple_strtoul(str, &str, 0);
> > -           /* avoid tail segment of size < IO_TLB_SEGSIZE */
> > -           io_tlb_nslabs = ALIGN(io_tlb_nslabs, IO_TLB_SEGSIZE);
> > +           /* avoid tail segment of size < io_tlb_segsize */
> > +           io_tlb_nslabs = ALIGN(io_tlb_nslabs, io_tlb_segsize);
> >     }
> >     if (*str == ',')
> >             ++str;
> > @@ -120,15 +137,26 @@ unsigned long swiotlb_nr_tbl(void)  }
> > EXPORT_SYMBOL_GPL(swiotlb_nr_tbl);
> >
> > -/* default to 64MB */
> > -#define IO_TLB_DEFAULT_SIZE (64UL<<20)
> > +/* default to 64MB
> > + * define io_tlb_default_size as a parameter
> > + * which can be changed dynamically in config file for special usage.
> > + */
> > +unsigned long io_tlb_default_size = (64UL<<20);
> > +
> > +static int __init
> > +   setup_io_tlb_default_size(char *str) {
> > +   get_option(&str, &io_tlb_default_size);
> > +   return 0;
> > +}
> > +__setup("io_tlb_default_size=", setup_io_tlb_default_size);
> 
> Please fold that in swiotlb=XYZ parameter. Make it do all the work.
> 
> > +
> >  unsigned long swiotlb_size_or_default(void)  {
> >     unsigned long size;
> >
> >     size = io_tlb_nslabs << IO_TLB_SHIFT;
> >
> > -   return size ? size : (IO_TLB_DEFAULT_SIZE);
> > +   return size ? size : (io_tlb_default_size);
> >  }
> >
> >  /* Note that this doesn't work with highmem page */ @@ -183,7 +211,7
> > @@ int __init swiotlb_init_with_tbl(char *tlb, unsigned long nslabs,
> > int verbose)
> >
> >     /*
> >      * Allocate and initialize the free list array.  This array is used
> > -    * to find contiguous free memory regions of size up to
> IO_TLB_SEGSIZE
> > +    * to find contiguous free memory regions of size up to
> > +io_tlb_segsize
> >      * between io_tlb_start and io_tlb_end.
> >      */
> >     io_tlb_list = memblock_virt_alloc(
> > @@ -193,7 +221,7 @@ int __init swiotlb_init_with_tbl(char *tlb, unsigned
> long nslabs, int verbose)
> >                             PAGE_ALIGN(io_tlb_nslabs *
> sizeof(phys_addr_t)),
> >                             PAGE_SIZE);
> >     for (i = 0; i < io_tlb_nslabs; i++) {
> > -           io_tlb_list[i] = IO_TLB_SEGSIZE - OFFSET(i, IO_TLB_SEGSIZE);
> > +           io_tlb_list[i] = io_tlb_segsize - OFFSET(i, io_tlb_segsize);
> >             io_tlb_orig_addr[i] = INVALID_PHYS_ADDR;
> >     }
> >     io_tlb_index = 0;
> > @@ -211,13 +239,13 @@ int __init swiotlb_init_with_tbl(char *tlb,
> > unsigned long nslabs, int verbose)  void  __init  swiotlb_init(int
> > verbose)  {
> > -   size_t default_size = IO_TLB_DEFAULT_SIZE;
> > +   size_t default_size = io_tlb_default_size;
> >     unsigned char *vstart;
> >     unsigned long bytes;
> >
> >     if (!io_tlb_nslabs) {
> >             io_tlb_nslabs = (default_size >> IO_TLB_SHIFT);
> > -           io_tlb_nslabs = ALIGN(io_tlb_nslabs, IO_TLB_SEGSIZE);
> > +           io_tlb_nslabs = ALIGN(io_tlb_nslabs, io_tlb_segsize);
> >     }
> >
> >     bytes = io_tlb_nslabs << IO_TLB_SHIFT; @@ -249,7 +277,7 @@
> > swiotlb_late_init_with_default_size(size_t default_size)
> >
> >     if (!io_tlb_nslabs) {
> >             io_tlb_nslabs = (default_size >> IO_TLB_SHIFT);
> > -           io_tlb_nslabs = ALIGN(io_tlb_nslabs, IO_TLB_SEGSIZE);
> > +           io_tlb_nslabs = ALIGN(io_tlb_nslabs, io_tlb_segsize);
> >     }
> >
> >     /*
> > @@ -308,7 +336,7 @@ swiotlb_late_init_with_tbl(char *tlb, unsigned
> > long nslabs)
> >
> >     /*
> >      * Allocate and initialize the free list array.  This array is used
> > -    * to find contiguous free memory regions of size up to
> IO_TLB_SEGSIZE
> > +    * to find contiguous free memory regions of size up to
> > +io_tlb_segsize
> >      * between io_tlb_start and io_tlb_end.
> >      */
> >     io_tlb_list = (unsigned int *)__get_free_pages(GFP_KERNEL, @@ -
> 324,7
> > +352,7 @@ swiotlb_late_init_with_tbl(char *tlb, unsigned long nslabs)
> >             goto cleanup4;
> >
> >     for (i = 0; i < io_tlb_nslabs; i++) {
> > -           io_tlb_list[i] = IO_TLB_SEGSIZE - OFFSET(i, IO_TLB_SEGSIZE);
> > +           io_tlb_list[i] = io_tlb_segsize - OFFSET(i, io_tlb_segsize);
> >             io_tlb_orig_addr[i] = INVALID_PHYS_ADDR;
> >     }
> >     io_tlb_index = 0;
> > @@ -493,7 +521,7 @@ phys_addr_t swiotlb_tbl_map_single(struct device
> > *hwdev,
> >
> >                     for (i = index; i < (int) (index + nslots); i++)
> >                             io_tlb_list[i] = 0;
> > -                   for (i = index - 1; (OFFSET(i, IO_TLB_SEGSIZE) !=
> IO_TLB_SEGSIZE - 1) && io_tlb_list[i]; i--)
> > +                   for (i = index - 1; (OFFSET(i, io_tlb_segsize) !=
> io_tlb_segsize -
> > +1) && io_tlb_list[i]; i--)
> >                             io_tlb_list[i] = ++count;
> >                     tlb_addr = io_tlb_start + (index << IO_TLB_SHIFT);
> >
> > @@ -571,7 +599,7 @@ void swiotlb_tbl_unmap_single(struct device
> *hwdev, phys_addr_t tlb_addr,
> >      */
> >     spin_lock_irqsave(&io_tlb_lock, flags);
> >     {
> > -           count = ((index + nslots) < ALIGN(index + 1, IO_TLB_SEGSIZE) ?
> > +           count = ((index + nslots) < ALIGN(index + 1, io_tlb_segsize) ?
> >                      io_tlb_list[index + nslots] : 0);
> >             /*
> >              * Step 1: return the slots to the free list, merging the @@ -
> 585,7
> > +613,7 @@ void swiotlb_tbl_unmap_single(struct device *hwdev,
> phys_addr_t tlb_addr,
> >              * Step 2: merge the returned slots with the preceding slots,
> >              * if available (non zero)
> >              */
> > -           for (i = index - 1; (OFFSET(i, IO_TLB_SEGSIZE) !=
> IO_TLB_SEGSIZE -1) && io_tlb_list[i]; i--)
> > +           for (i = index - 1; (OFFSET(i, io_tlb_segsize) != io_tlb_segsize
> > +-1) && io_tlb_list[i]; i--)
> >                     io_tlb_list[i] = ++count;
> >     }
> >     spin_unlock_irqrestore(&io_tlb_lock, flags);
> > --
> > 1.7.9.5
> >

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