On 19/03/2019 07:59, Lu Baolu wrote:
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.
I'd imagine the thing to do would be to factor out the slot allocation
in swiotlb_tbl_map_single() so that an IOMMU page pool/allocator can be
hooked in as an alternative.
However we implement it, though, this should absolutely be a common
IOMMU thing that all relevant DMA backends can opt into, and not
specific to VT-d. I mean, it's already more or less the same concept as
the PowerPC secure VM thing.
Robin.
_______________________________________________
iommu mailing list
iommu@lists.linux-foundation.org
https://lists.linuxfoundation.org/mailman/listinfo/iommu
