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    Subject[PATCH v9 11/18] swiotlb-xen: use xen_alloc/free_coherent_pages
    Date
    Use xen_alloc_coherent_pages and xen_free_coherent_pages to allocate or
    free coherent pages.

    We need to be careful handling the pointer returned by
    xen_alloc_coherent_pages, because on ARM the pointer is not equal to
    phys_to_virt(*dma_handle). In fact virt_to_phys only works for kernel
    direct mapped RAM memory.
    In ARM case the pointer could be an ioremap address, therefore passing
    it to virt_to_phys would give you another physical address that doesn't
    correspond to it.

    Make xen_create_contiguous_region take a phys_addr_t as start parameter to
    avoid the virt_to_phys calls which would be incorrect.

    Changes in v6:
    - remove extra spaces.

    Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
    Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
    ---
    arch/arm/xen/mm.c | 6 +++---
    arch/x86/xen/mmu.c | 7 +++++--
    drivers/xen/swiotlb-xen.c | 31 +++++++++++++++++++++----------
    include/xen/xen-ops.h | 4 ++--
    4 files changed, 31 insertions(+), 17 deletions(-)

    diff --git a/arch/arm/xen/mm.c b/arch/arm/xen/mm.c
    index 0d69b87..b0e77de 100644
    --- a/arch/arm/xen/mm.c
    +++ b/arch/arm/xen/mm.c
    @@ -16,7 +16,7 @@
    #include <asm/xen/hypercall.h>
    #include <asm/xen/interface.h>

    -int xen_create_contiguous_region(unsigned long vstart, unsigned int order,
    +int xen_create_contiguous_region(phys_addr_t pstart, unsigned int order,
    unsigned int address_bits,
    dma_addr_t *dma_handle)
    {
    @@ -24,12 +24,12 @@ int xen_create_contiguous_region(unsigned long vstart, unsigned int order,
    return -EINVAL;

    /* we assume that dom0 is mapped 1:1 for now */
    - *dma_handle = virt_to_phys(pstart);
    + *dma_handle = pstart;
    return 0;
    }
    EXPORT_SYMBOL_GPL(xen_create_contiguous_region);

    -void xen_destroy_contiguous_region(unsigned long vstart, unsigned int order)
    +void xen_destroy_contiguous_region(phys_addr_t pstart, unsigned int order)
    {
    return;
    }
    diff --git a/arch/x86/xen/mmu.c b/arch/x86/xen/mmu.c
    index 6c34d7c..8830883 100644
    --- a/arch/x86/xen/mmu.c
    +++ b/arch/x86/xen/mmu.c
    @@ -2328,13 +2328,14 @@ static int xen_exchange_memory(unsigned long extents_in, unsigned int order_in,
    return success;
    }

    -int xen_create_contiguous_region(unsigned long vstart, unsigned int order,
    +int xen_create_contiguous_region(phys_addr_t pstart, unsigned int order,
    unsigned int address_bits,
    dma_addr_t *dma_handle)
    {
    unsigned long *in_frames = discontig_frames, out_frame;
    unsigned long flags;
    int success;
    + unsigned long vstart = (unsigned long)phys_to_virt(pstart);

    /*
    * Currently an auto-translated guest will not perform I/O, nor will
    @@ -2374,11 +2375,12 @@ int xen_create_contiguous_region(unsigned long vstart, unsigned int order,
    }
    EXPORT_SYMBOL_GPL(xen_create_contiguous_region);

    -void xen_destroy_contiguous_region(unsigned long vstart, unsigned int order)
    +void xen_destroy_contiguous_region(phys_addr_t pstart, unsigned int order)
    {
    unsigned long *out_frames = discontig_frames, in_frame;
    unsigned long flags;
    int success;
    + unsigned long vstart;

    if (xen_feature(XENFEAT_auto_translated_physmap))
    return;
    @@ -2386,6 +2388,7 @@ void xen_destroy_contiguous_region(unsigned long vstart, unsigned int order)
    if (unlikely(order > MAX_CONTIG_ORDER))
    return;

    + vstart = (unsigned long)phys_to_virt(pstart);
    memset((void *) vstart, 0, PAGE_SIZE << order);

    spin_lock_irqsave(&xen_reservation_lock, flags);
    diff --git a/drivers/xen/swiotlb-xen.c b/drivers/xen/swiotlb-xen.c
    index d8ef0bf..189b8db 100644
    --- a/drivers/xen/swiotlb-xen.c
    +++ b/drivers/xen/swiotlb-xen.c
    @@ -43,6 +43,7 @@
    #include <xen/xen-ops.h>
    #include <xen/hvc-console.h>
    #include <asm/dma-mapping.h>
    +#include <asm/xen/page-coherent.h>
    /*
    * 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
    @@ -142,6 +143,7 @@ xen_swiotlb_fixup(void *buf, size_t size, unsigned long nslabs)
    int i, rc;
    int dma_bits;
    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;

    @@ -151,7 +153,7 @@ xen_swiotlb_fixup(void *buf, size_t size, unsigned long nslabs)

    do {
    rc = xen_create_contiguous_region(
    - (unsigned long)buf + (i << IO_TLB_SHIFT),
    + p + (i << IO_TLB_SHIFT),
    get_order(slabs << IO_TLB_SHIFT),
    dma_bits, &dma_handle);
    } while (rc && dma_bits++ < max_dma_bits);
    @@ -279,7 +281,6 @@ xen_swiotlb_alloc_coherent(struct device *hwdev, size_t size,
    void *ret;
    int order = get_order(size);
    u64 dma_mask = DMA_BIT_MASK(32);
    - unsigned long vstart;
    phys_addr_t phys;
    dma_addr_t dev_addr;

    @@ -294,8 +295,12 @@ xen_swiotlb_alloc_coherent(struct device *hwdev, size_t size,
    if (dma_alloc_from_coherent(hwdev, size, dma_handle, &ret))
    return ret;

    - vstart = __get_free_pages(flags, order);
    - ret = (void *)vstart;
    + /* On ARM this function returns an ioremap'ped virtual address for
    + * which virt_to_phys doesn't return the corresponding physical
    + * address. In fact on ARM virt_to_phys only works for kernel direct
    + * mapped RAM memory. Also see comment below.
    + */
    + ret = xen_alloc_coherent_pages(hwdev, size, dma_handle, flags, attrs);

    if (!ret)
    return ret;
    @@ -303,15 +308,19 @@ xen_swiotlb_alloc_coherent(struct device *hwdev, size_t size,
    if (hwdev && hwdev->coherent_dma_mask)
    dma_mask = dma_alloc_coherent_mask(hwdev, flags);

    - phys = virt_to_phys(ret);
    + /* At this point dma_handle is the physical address, next we are
    + * going to set it to the machine address.
    + * Do not use virt_to_phys(ret) because on ARM it doesn't correspond
    + * to *dma_handle. */
    + phys = *dma_handle;
    dev_addr = xen_phys_to_bus(phys);
    if (((dev_addr + size - 1 <= dma_mask)) &&
    !range_straddles_page_boundary(phys, size))
    *dma_handle = dev_addr;
    else {
    - if (xen_create_contiguous_region(vstart, order,
    + if (xen_create_contiguous_region(phys, order,
    fls64(dma_mask), dma_handle) != 0) {
    - free_pages(vstart, order);
    + xen_free_coherent_pages(hwdev, size, ret, (dma_addr_t)phys, attrs);
    return NULL;
    }
    }
    @@ -334,13 +343,15 @@ xen_swiotlb_free_coherent(struct device *hwdev, size_t size, void *vaddr,
    if (hwdev && hwdev->coherent_dma_mask)
    dma_mask = hwdev->coherent_dma_mask;

    - phys = virt_to_phys(vaddr);
    + /* do not use virt_to_phys because on ARM it doesn't return you the
    + * physical address */
    + phys = xen_bus_to_phys(dev_addr);

    if (((dev_addr + size - 1 > dma_mask)) ||
    range_straddles_page_boundary(phys, size))
    - xen_destroy_contiguous_region((unsigned long)vaddr, order);
    + xen_destroy_contiguous_region(phys, order);

    - free_pages((unsigned long)vaddr, order);
    + xen_free_coherent_pages(hwdev, size, vaddr, (dma_addr_t)phys, attrs);
    }
    EXPORT_SYMBOL_GPL(xen_swiotlb_free_coherent);

    diff --git a/include/xen/xen-ops.h b/include/xen/xen-ops.h
    index 9ef704d..fb2ea8f 100644
    --- a/include/xen/xen-ops.h
    +++ b/include/xen/xen-ops.h
    @@ -19,11 +19,11 @@ void xen_arch_resume(void);
    int xen_setup_shutdown_event(void);

    extern unsigned long *xen_contiguous_bitmap;
    -int xen_create_contiguous_region(unsigned long vstart, unsigned int order,
    +int xen_create_contiguous_region(phys_addr_t pstart, unsigned int order,
    unsigned int address_bits,
    dma_addr_t *dma_handle);

    -void xen_destroy_contiguous_region(unsigned long vstart, unsigned int order);
    +void xen_destroy_contiguous_region(phys_addr_t pstart, unsigned int order);

    struct vm_area_struct;
    int xen_remap_domain_mfn_range(struct vm_area_struct *vma,
    --
    1.7.2.5


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