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    SubjectRe: [PATCH 01/10] swiotlb-xen: use vmalloc_to_page on vmalloc virt addresses
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    Hi,

    On 21/05/2020 00:45, Stefano Stabellini wrote:
    > From: Boris Ostrovsky <boris.ostrovsky@oracle.com>
    >
    > Don't just assume that virt_to_page works on all virtual addresses.
    > Instead add a is_vmalloc_addr check and use vmalloc_to_page on vmalloc
    > virt addresses.

    Can you provide an example where swiotlb is used with vmalloc()?

    > Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
    > Signed-off-by: Stefano Stabellini <stefano.stabellini@xilinx.com>
    > ---
    > drivers/xen/swiotlb-xen.c | 5 ++++-
    > 1 file changed, 4 insertions(+), 1 deletion(-)
    >
    > diff --git a/drivers/xen/swiotlb-xen.c b/drivers/xen/swiotlb-xen.c
    > index b6d27762c6f8..a42129cba36e 100644
    > --- a/drivers/xen/swiotlb-xen.c
    > +++ b/drivers/xen/swiotlb-xen.c
    > @@ -335,6 +335,7 @@ xen_swiotlb_free_coherent(struct device *hwdev, size_t size, void *vaddr,
    > int order = get_order(size);
    > phys_addr_t phys;
    > u64 dma_mask = DMA_BIT_MASK(32);
    > + struct page *pg;
    >
    > if (hwdev && hwdev->coherent_dma_mask)
    > dma_mask = hwdev->coherent_dma_mask;
    > @@ -346,9 +347,11 @@ xen_swiotlb_free_coherent(struct device *hwdev, size_t size, void *vaddr,
    > /* Convert the size to actually allocated. */
    > size = 1UL << (order + XEN_PAGE_SHIFT);
    >
    > + pg = is_vmalloc_addr(vaddr) ? vmalloc_to_page(vaddr) :
    > + virt_to_page(vaddr);

    Common DMA code seems to protect this check with CONFIG_DMA_REMAP. Is it
    something we want to do it here as well? Or is there any other condition
    where vmalloc can happen?

    > if (!WARN_ON((dev_addr + size - 1 > dma_mask) ||
    > range_straddles_page_boundary(phys, size)) &&
    > - TestClearPageXenRemapped(virt_to_page(vaddr)))
    > + TestClearPageXenRemapped(pg))
    > xen_destroy_contiguous_region(phys, order);
    >
    > xen_free_coherent_pages(hwdev, size, vaddr, (dma_addr_t)phys, attrs);
    >

    Cheers,

    --
    Julien Grall

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