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    Subject[PATCH 04/10] x86/swiotlb: Simplify SWIOTLB pci_swiotlb_detect routine.
    Date
    In 'pci_swiotlb_detect' we used to do two different things:
    a). If user provided 'iommu=soft' or 'swiotlb=force' we
    would set swiotlb=1 and return 1 (and forcing pci-dma.c
    to call pci_swiotlb_init() immediately).
    b). If 4GB or more would be detected and if user did not specify
    iommu=off, we would set 'swiotlb=1' and return whatever 'a)'
    figured out.

    We simplify this by splitting a) and b) in two different routines.

    CC: H. Peter Anvin <hpa@zytor.com>
    CC: Fujita Tomonori <fujita.tomonori@lab.ntt.co.jp>
    CC: x86@kernel.org
    Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
    ---
    arch/x86/include/asm/iommu_table.h | 4 ++--
    arch/x86/include/asm/swiotlb.h | 13 +++++++++++--
    arch/x86/kernel/pci-dma.c | 4 +++-
    arch/x86/kernel/pci-swiotlb.c | 33 +++++++++++++++++++++++++++------
    4 files changed, 43 insertions(+), 11 deletions(-)

    diff --git a/arch/x86/include/asm/iommu_table.h b/arch/x86/include/asm/iommu_table.h
    index 2124e3e..df55a78 100644
    --- a/arch/x86/include/asm/iommu_table.h
    +++ b/arch/x86/include/asm/iommu_table.h
    @@ -64,10 +64,10 @@ struct iommu_table_entry {
    * to stop detecting the other IOMMUs after yours has been detected.
    */
    #define IOMMU_INIT_POST(_detect) \
    - __IOMMU_INIT(_detect, pci_swiotlb_detect, 0, 0, 0)
    + __IOMMU_INIT(_detect, pci_swiotlb_detect_4gb, 0, 0, 0)

    #define IOMMU_INIT_POST_FINISH(detect) \
    - __IOMMU_INIT(_detect, pci_swiotlb_detect, 0, 0, 1)
    + __IOMMU_INIT(_detect, pci_swiotlb_detect_4gb, 0, 0, 1)

    /*
    * A more sophisticated version of IOMMU_INIT. This variant requires:
    diff --git a/arch/x86/include/asm/swiotlb.h b/arch/x86/include/asm/swiotlb.h
    index 8085277..977f176 100644
    --- a/arch/x86/include/asm/swiotlb.h
    +++ b/arch/x86/include/asm/swiotlb.h
    @@ -5,17 +5,26 @@

    #ifdef CONFIG_SWIOTLB
    extern int swiotlb;
    -extern int __init pci_swiotlb_detect(void);
    +extern int __init pci_swiotlb_detect_override(void);
    +extern int __init pci_swiotlb_detect_4gb(void);
    extern void __init pci_swiotlb_init(void);
    +extern void __init pci_swiotlb_late_init(void);
    #else
    #define swiotlb 0
    -static inline int pci_swiotlb_detect(void)
    +static inline int pci_swiotlb_detect_override(void)
    +{
    + return 0;
    +}
    +static inline int pci_swiotlb_detect_4gb(void)
    {
    return 0;
    }
    static inline void pci_swiotlb_init(void)
    {
    }
    +static inline void pci_swiotlb_late_init(void)
    +{
    +}
    #endif

    static inline void dma_mark_clean(void *addr, size_t size) {}
    diff --git a/arch/x86/kernel/pci-dma.c b/arch/x86/kernel/pci-dma.c
    index 9f07cfc..1b3beb5 100644
    --- a/arch/x86/kernel/pci-dma.c
    +++ b/arch/x86/kernel/pci-dma.c
    @@ -133,9 +133,11 @@ void __init pci_iommu_alloc(void)
    /* free the range so iommu could get some range less than 4G */
    dma32_free_bootmem();

    - if (pci_xen_swiotlb_detect() || pci_swiotlb_detect())
    + if (pci_xen_swiotlb_detect() || pci_swiotlb_detect_override())
    goto out;

    + pci_swiotlb_detect_4gb();
    +
    gart_iommu_hole_init();

    detect_calgary();
    diff --git a/arch/x86/kernel/pci-swiotlb.c b/arch/x86/kernel/pci-swiotlb.c
    index a5bc528..c7a72fa 100644
    --- a/arch/x86/kernel/pci-swiotlb.c
    +++ b/arch/x86/kernel/pci-swiotlb.c
    @@ -41,24 +41,33 @@ static struct dma_map_ops swiotlb_dma_ops = {
    };

    /*
    - * pci_swiotlb_detect - set swiotlb to 1 if necessary
    + * pci_swiotlb_detect_override - set swiotlb to 1 if necessary
    *
    * This returns non-zero if we are forced to use swiotlb (by the boot
    * option).
    */
    -int __init pci_swiotlb_detect(void)
    +int __init pci_swiotlb_detect_override(void)
    {
    int use_swiotlb = swiotlb | swiotlb_force;

    + if (swiotlb_force)
    + swiotlb = 1;
    +
    + return use_swiotlb;
    +}
    +
    +/*
    + * if 4GB or more detected (and iommu=off not set) return 1
    + * and set swiotlb to 1.
    + */
    +int __init pci_swiotlb_detect_4gb(void)
    +{
    /* don't initialize swiotlb if iommu=off (no_iommu=1) */
    #ifdef CONFIG_X86_64
    if (!no_iommu && max_pfn > MAX_DMA32_PFN)
    swiotlb = 1;
    #endif
    - if (swiotlb_force)
    - swiotlb = 1;
    -
    - return use_swiotlb;
    + return swiotlb;
    }

    void __init pci_swiotlb_init(void)
    @@ -68,3 +77,15 @@ void __init pci_swiotlb_init(void)
    dma_ops = &swiotlb_dma_ops;
    }
    }
    +
    +void __init pci_swiotlb_late_init(void)
    +{
    + /* An IOMMU turned us off. */
    + if (!swiotlb)
    + swiotlb_free();
    + else {
    + printk(KERN_INFO "PCI-DMA: "
    + "Using software bounce buffering for IO (SWIOTLB)\n");
    + swiotlb_print_info();
    + }
    +}
    --
    1.7.0.1


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