On 11/10/2017 02:09, Robin Murphy wrote: > The VIA VL805 host controller is well-known for causing problems on > systems with IOMMUs enabled, ranging from triggering endless streams of > fault messages to locking itself up completely. It appears that the root > of the problem might be an over-aggressive prefetching of TRBs, wherein > consuming commands near the end of a queue segment causes it to read off > the end of the segment, even across a page boundary. This blows up when > DMA mapping ops are backed by an IOMMU, since there is no guarantee that > addresses outside the allocated segment are accessible at all. > > Some trial-and-error investigation reveals that we can avoid such > cross-page reads by not using the last few TRBs in a segment; to that > end, factor out the implicit index of the end-of-segemnt link TRB, and > implement a quirk to move it slightly further forward when necessary. > > Signed-off-by: Robin Murphy <robin.murphy@xxxxxxx> > --- > drivers/usb/host/xhci-mem.c | 32 +++++++++++++++++++------------- > drivers/usb/host/xhci-pci.c | 5 +++++ > drivers/usb/host/xhci-ring.c | 10 +++++++++- > drivers/usb/host/xhci.c | 10 +++++----- > drivers/usb/host/xhci.h | 2 ++ > 5 files changed, 40 insertions(+), 19 deletions(-) Seems like the invalid DMA I'm getting on xhci_reset during the xhci driver's initialisation/probing process isn't the same one you're getting.. This patch doesn't appear to change that at all. Oh well. Thanks, -- Hao Wei -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
