Messages in this thread Patch in this message | | | From | Joe Jin <> | Subject | [PATCH V2] xen-swiotlb: exchange memory with Xen only when pages are contiguous | Date | Wed, 24 Oct 2018 20:08:54 -0700 |
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Commit 4855c92dbb7 "xen-swiotlb: fix the check condition for xen_swiotlb_free_coherent" only fixed memory address check condition on xen_swiotlb_free_coherent(), when memory was not physically contiguous and tried to exchanged with Xen via xen_destroy_contiguous_region which lead to kernel panic.
The correct check conditions to make Xen hypercall to revert the memory back from its 32-bit pool are: 1) Above its DMA bit mask (for example 32-bit devices can only address up to 4GB, and we may want 4GB+2K), and 2) It's physically contiguous.
Thank you Boris for pointing it out.
Fixes: 4855c92dbb7 ("xen-swiotlb: fix the check condition for xen_swiotlb_free_coherent"
Signed-off-by: Joe Jin <joe.jin@oracle.com> Reported-by: Boris Ostrovsky <boris.ostrovsky@oracle.com> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Cc: Christoph Helwig <hch@lst.de> Cc: Dongli Zhang <dongli.zhang@oracle.com> Cc: John Sobecki <john.sobecki@oracle.com> --- drivers/xen/swiotlb-xen.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/drivers/xen/swiotlb-xen.c b/drivers/xen/swiotlb-xen.c index f5c1af4ce9ab..aed92fa019f9 100644 --- a/drivers/xen/swiotlb-xen.c +++ b/drivers/xen/swiotlb-xen.c @@ -357,8 +357,8 @@ xen_swiotlb_free_coherent(struct device *hwdev, size_t size, void *vaddr, /* Convert the size to actually allocated. */ size = 1UL << (order + XEN_PAGE_SHIFT); - if (((dev_addr + size - 1 <= dma_mask)) || - range_straddles_page_boundary(phys, size)) + if ((dev_addr + size - 1 <= dma_mask) && + !range_straddles_page_boundary(phys, size)) xen_destroy_contiguous_region(phys, order); xen_free_coherent_pages(hwdev, size, vaddr, (dma_addr_t)phys, attrs); -- 2.17.1 (Apple Git-112)
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