Messages in this thread | | | Subject | Re: [PATCH v1 4/9] iommu/vt-d: Add bounce buffer API for domain map/unmap | From | Lu Baolu <> | Date | Tue, 19 Mar 2019 15:59:48 +0800 |
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Hi Christoph,
On 3/14/19 12:10 AM, Christoph Hellwig wrote: > On Wed, Mar 13, 2019 at 10:31:52AM +0800, Lu Baolu wrote: >> Hi again, >> >> On 3/13/19 10:04 AM, Lu Baolu wrote: >>> Hi, >>> >>> On 3/13/19 12:38 AM, Christoph Hellwig wrote: >>>> On Tue, Mar 12, 2019 at 02:00:00PM +0800, Lu Baolu wrote: >>>>> This adds the APIs for bounce buffer specified domain >>>>> map() and unmap(). The start and end partial pages will >>>>> be mapped with bounce buffered pages instead. This will >>>>> enhance the security of DMA buffer by isolating the DMA >>>>> attacks from malicious devices. >>>> >>>> Please reuse the swiotlb code instead of reinventing it. >>>> >> >> Just looked into the code again. At least we could reuse below >> functions: >> >> swiotlb_tbl_map_single() >> swiotlb_tbl_unmap_single() >> swiotlb_tbl_sync_single() >> >> Anything else? > > Yes, that is probably about the level you want to reuse, given that the > next higher layer already has hooks into the direct mapping code. >
I am trying to change my code to reuse swiotlb. But I found that swiotlb might not be suitable for my case.
Below is what I got with swiotlb_map():
phy_addr size tlb_addr -------------------------------- 0x167eec330 0x8 0x85dc6000 0x167eef5c0 0x40 0x85dc6800 0x167eec330 0x8 0x85dc7000 0x167eef5c0 0x40 0x85dc7800
But what I expected to get is:
phy_addr size tlb_addr -------------------------------- 0x167eec330 0x8 0xAAAAA330 0x167eef5c0 0x40 0xBBBBB5c0 0x167eec330 0x8 0xCCCCC330 0x167eef5c0 0x40 0xDDDDD5c0
, where 0xXXXXXX000 is the physical address of a bounced page.
Basically, I want a bounce page to replace a leaf page in the vt-d page table, which maps a buffer with size less than a PAGE_SIZE.
Best regards, Lu Baolu
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