05/10/2018 14:45, Alejandro Lucero: > I sent a patchset about this to be applied on 17.11 stable. The memory > code has had main changes since that version, so here it is the patchset > adjusted to current master repo. > > This patchset adds, mainly, a check for ensuring IOVAs are within a > restricted range due to addressing limitations with some devices. There > are two known cases: NFP and IOMMU VT-d emulation. > > With this check IOVAs out of range are detected and PMDs can abort > initialization. For the VT-d case, IOVA VA mode is allowed as long as > IOVAs are within the supported range, avoiding to forbid IOVA VA by > default. > > For the addressing limitations known cases, there are just 40(NFP) or > 39(VT-d) bits for handling IOVAs. When using IOVA PA, those limitations > imply 1TB(NFP) or 512M(VT-d) as upper limits, which is likely enough for > most systems. With machines using more memory, the added check will > ensure IOVAs within the range. > > With IOVA VA, and because the way the Linux kernel serves mmap calls > in 64 bits systems, 39 or 40 bits are not enough. It is possible to > give an address hint with a lower starting address than the default one > used by the kernel, and then ensuring the mmap uses that hint or hint plus > some offset. With 64 bits systems, the process virtual address space is > large enoguh for doing the hugepages mmaping within the supported range > when those addressing limitations exist. This patchset also adds a change > for using such a hint making the use of IOVA VA a more than likely > possibility when there are those addressing limitations. > > The check is not done by default but just when it is required. This > patchset adds the check for NFP initialization and for setting the IOVA > mode is an emulated VT-d is detected. Also, because the recent patchset > adding dynamic memory allocation, the check is also invoked for ensuring > the new memsegs are within the required range. > > This patchset could be applied to stable 18.05.
Applied, thanks
