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    Subject[PATCH 4/5] xen/swiotlb: Use the swiotlb_late_init_with_tbl to init Xen-SWIOTLB late when PV PCI is used.
    Date
    With this patch we provide the functionality to initialize the
    Xen-SWIOTLB late in the bootup cycle - specifically for
    Xen PCI-frontend. We still will work if the user had
    supplied 'iommu=soft' on the Linux command line.

    CC: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
    Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
    ---
    arch/x86/include/asm/xen/swiotlb-xen.h | 2 +
    arch/x86/xen/pci-swiotlb-xen.c | 17 ++++++++++-
    drivers/xen/swiotlb-xen.c | 50 +++++++++++++++++++++++++++----
    include/xen/swiotlb-xen.h | 1 +
    4 files changed, 62 insertions(+), 8 deletions(-)

    diff --git a/arch/x86/include/asm/xen/swiotlb-xen.h b/arch/x86/include/asm/xen/swiotlb-xen.h
    index 1be1ab7..ee52fca 100644
    --- a/arch/x86/include/asm/xen/swiotlb-xen.h
    +++ b/arch/x86/include/asm/xen/swiotlb-xen.h
    @@ -5,10 +5,12 @@
    extern int xen_swiotlb;
    extern int __init pci_xen_swiotlb_detect(void);
    extern void __init pci_xen_swiotlb_init(void);
    +extern int pci_xen_swiotlb_init_late(void);
    #else
    #define xen_swiotlb (0)
    static inline int __init pci_xen_swiotlb_detect(void) { return 0; }
    static inline void __init pci_xen_swiotlb_init(void) { }
    +static inline int pci_xen_swiotlb_init_late(void) { return -ENXIO; }
    #endif

    #endif /* _ASM_X86_SWIOTLB_XEN_H */
    diff --git a/arch/x86/xen/pci-swiotlb-xen.c b/arch/x86/xen/pci-swiotlb-xen.c
    index 0d5a214..bc2daf6 100644
    --- a/arch/x86/xen/pci-swiotlb-xen.c
    +++ b/arch/x86/xen/pci-swiotlb-xen.c
    @@ -12,7 +12,7 @@
    #include <asm/iommu.h>
    #include <asm/dma.h>
    #endif
    -
    +#include <linux/export.h>
    int xen_swiotlb __read_mostly;

    static struct dma_map_ops xen_swiotlb_dma_ops = {
    @@ -74,6 +74,21 @@ void __init pci_xen_swiotlb_init(void)
    pci_request_acs();
    }
    }
    +
    +int pci_xen_swiotlb_init_late(void)
    +{
    + int rc = xen_swiotlb_late_init(1);
    + if (rc)
    + return rc;
    +
    + dma_ops = &xen_swiotlb_dma_ops;
    + /* Make sure ACS will be enabled */
    + pci_request_acs();
    +
    + return 0;
    +}
    +EXPORT_SYMBOL_GPL(pci_xen_swiotlb_init_late);
    +
    IOMMU_INIT_FINISH(pci_xen_swiotlb_detect,
    0,
    pci_xen_swiotlb_init,
    diff --git a/drivers/xen/swiotlb-xen.c b/drivers/xen/swiotlb-xen.c
    index 1afb4fb..8805e94 100644
    --- a/drivers/xen/swiotlb-xen.c
    +++ b/drivers/xen/swiotlb-xen.c
    @@ -145,13 +145,14 @@ xen_swiotlb_fixup(void *buf, size_t size, unsigned long nslabs)
    return 0;
    }

    -void __init xen_swiotlb_init(int verbose)
    +int __xen_swiotlb_init(int verbose, bool early)
    {
    unsigned long bytes;
    int rc = -ENOMEM;
    unsigned long nr_tbl;
    char *m = NULL;
    unsigned int repeat = 3;
    + unsigned long order;

    nr_tbl = swiotlb_nr_tbl();
    if (nr_tbl)
    @@ -161,12 +162,31 @@ void __init xen_swiotlb_init(int verbose)
    xen_io_tlb_nslabs = ALIGN(xen_io_tlb_nslabs, IO_TLB_SEGSIZE);
    }
    retry:
    + order = get_order(xen_io_tlb_nslabs << IO_TLB_SHIFT);
    bytes = xen_io_tlb_nslabs << IO_TLB_SHIFT;

    /*
    * Get IO TLB memory from any location.
    */
    - xen_io_tlb_start = alloc_bootmem_pages(PAGE_ALIGN(bytes));
    + if (early)
    + xen_io_tlb_start = alloc_bootmem_pages(PAGE_ALIGN(bytes));
    + else {
    +#define SLABS_PER_PAGE (1 << (PAGE_SHIFT - IO_TLB_SHIFT))
    +#define IO_TLB_MIN_SLABS ((1<<20) >> IO_TLB_SHIFT)
    +
    + while ((SLABS_PER_PAGE << order) > IO_TLB_MIN_SLABS) {
    + xen_io_tlb_start = (void *)__get_free_pages(__GFP_NOWARN, order);
    + if (xen_io_tlb_start)
    + break;
    + order--;
    + }
    + if (order != get_order(bytes)) {
    + pr_warn("Warning: only able to allocate %ld MB "
    + "for software IO TLB\n", (PAGE_SIZE << order) >> 20);
    + xen_io_tlb_nslabs = SLABS_PER_PAGE << order;
    + bytes = xen_io_tlb_nslabs << IO_TLB_SHIFT;
    + }
    + }
    if (!xen_io_tlb_start) {
    m = "Cannot allocate Xen-SWIOTLB buffer!\n";
    goto error;
    @@ -179,7 +199,8 @@ retry:
    bytes,
    xen_io_tlb_nslabs);
    if (rc) {
    - free_bootmem(__pa(xen_io_tlb_start), PAGE_ALIGN(bytes));
    + if (early)
    + free_bootmem(__pa(xen_io_tlb_start), PAGE_ALIGN(bytes));
    m = "Failed to get contiguous memory for DMA from Xen!\n"\
    "You either: don't have the permissions, do not have"\
    " enough free memory under 4GB, or the hypervisor memory"\
    @@ -187,9 +208,13 @@ retry:
    goto error;
    }
    start_dma_addr = xen_virt_to_bus(xen_io_tlb_start);
    - swiotlb_init_with_tbl(xen_io_tlb_start, xen_io_tlb_nslabs, verbose);

    - return;
    + rc = 0;
    + if (early)
    + swiotlb_init_with_tbl(xen_io_tlb_start, xen_io_tlb_nslabs, verbose);
    + else
    + rc = swiotlb_late_init_with_tbl(xen_io_tlb_start, xen_io_tlb_nslabs);
    + return rc;
    error:
    if (repeat--) {
    xen_io_tlb_nslabs = max(1024UL, /* Min is 2MB */
    @@ -199,9 +224,20 @@ error:
    goto retry;
    }
    xen_raw_printk("%s (rc:%d)", m, rc);
    - panic("%s (rc:%d)", m, rc);
    + if (early)
    + panic("%s (rc:%d)", m, rc);
    + else
    + free_pages((unsigned long)xen_io_tlb_start, order);
    + return rc;
    +}
    +void __init xen_swiotlb_init(int verbose)
    +{
    + __xen_swiotlb_init(verbose, true /* early */);
    +}
    +int xen_swiotlb_late_init(int verbose)
    +{
    + return __xen_swiotlb_init(verbose, false /* late */);
    }
    -
    void *
    xen_swiotlb_alloc_coherent(struct device *hwdev, size_t size,
    dma_addr_t *dma_handle, gfp_t flags,
    diff --git a/include/xen/swiotlb-xen.h b/include/xen/swiotlb-xen.h
    index 4f4d449..d38d984 100644
    --- a/include/xen/swiotlb-xen.h
    +++ b/include/xen/swiotlb-xen.h
    @@ -4,6 +4,7 @@
    #include <linux/swiotlb.h>

    extern void xen_swiotlb_init(int verbose);
    +extern int xen_swiotlb_late_init(int verbose);

    extern void
    *xen_swiotlb_alloc_coherent(struct device *hwdev, size_t size,
    --
    1.7.7.6


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