On Thu, Jun 28, 2018 at 11:03 AM, Burakov, Anatoly < anatoly.bura...@intel.com> wrote:
> On 28-Jun-18 10:56 AM, Alejandro Lucero wrote: > >> >> >> On Thu, Jun 28, 2018 at 9:54 AM, Burakov, Anatoly < >> anatoly.bura...@intel.com <mailto:anatoly.bura...@intel.com>> wrote: >> >> On 27-Jun-18 5:52 PM, Alejandro Lucero wrote: >> >> >> >> On Wed, Jun 27, 2018 at 2:24 PM, Burakov, Anatoly >> <anatoly.bura...@intel.com <mailto:anatoly.bura...@intel.com> >> <mailto:anatoly.bura...@intel.com >> <mailto:anatoly.bura...@intel.com>>> wrote: >> >> On 27-Jun-18 11:13 AM, Alejandro Lucero wrote: >> >> >> >> On Wed, Jun 27, 2018 at 9:17 AM, Burakov, Anatoly >> <anatoly.bura...@intel.com >> <mailto:anatoly.bura...@intel.com> >> <mailto:anatoly.bura...@intel.com >> <mailto:anatoly.bura...@intel.com>> >> <mailto:anatoly.bura...@intel.com >> <mailto:anatoly.bura...@intel.com> >> >> <mailto:anatoly.bura...@intel.com >> <mailto:anatoly.bura...@intel.com>>>> wrote: >> >> On 26-Jun-18 6:37 PM, Alejandro Lucero wrote: >> >> This RFC tries to handle devices with addressing >> limitations. >> NFP devices >> 4000/6000 can just handle addresses with 40 >> bits implying >> problems for handling >> physical address when machines have more than >> 1TB of >> memory. But >> because how >> iovas are configured, which can be equivalent >> to physical >> addresses or based on >> virtual addresses, this can be a more likely >> problem. >> >> I tried to solve this some time ago: >> >> https://www.mail-archive.com/dev@dpdk.org/msg45214.html >> <https://www.mail-archive.com/dev@dpdk.org/msg45214.html> >> <https://www.mail-archive.com/ >> dev@dpdk.org/msg45214.html >> <https://www.mail-archive.com/dev@dpdk.org/msg45214.html>> >> <https://www.mail-archive.com/ >> dev@dpdk.org/msg45214.html >> <https://www.mail-archive.com/dev@dpdk.org/msg45214.html> >> <https://www.mail-archive.com/ >> dev@dpdk.org/msg45214.html >> <https://www.mail-archive.com/dev@dpdk.org/msg45214.html>>> >> >> It was delayed because there was some changes in >> progress with >> EAL device >> handling, and, being honest, I completely >> forgot about this >> until now, when >> I have had to work on supporting NFP devices >> with DPDK and >> non-root users. >> >> I was working on a patch for being applied on >> main DPDK >> branch >> upstream, but >> because changes to memory initialization >> during the >> last months, >> this can not >> be backported to stable versions, at least the >> part >> where the >> hugepages iovas >> are checked. >> >> I realize stable versions only allow bug >> fixing, and this >> patchset could >> arguably not be considered as so. But without >> this, it >> could be, >> although >> unlikely, a DPDK used in a machine with more >> than 1TB, >> and then >> NFP using >> the wrong DMA host addresses. >> >> Although virtual addresses used as iovas are >> more >> dangerous, for >> DPDK versions >> before 18.05 this is not worse than with >> physical >> addresses, >> because iovas, >> when physical addresses are not available, are >> based on a >> starting address set >> to 0x0. >> >> >> You might want to look at the following patch: >> >> http://patches.dpdk.org/patch/37149/ >> <http://patches.dpdk.org/patch/37149/> >> <http://patches.dpdk.org/patch/37149/ >> <http://patches.dpdk.org/patch/37149/>> >> <http://patches.dpdk.org/patch/37149/ >> <http://patches.dpdk.org/patch/37149/> >> <http://patches.dpdk.org/patch/37149/ >> <http://patches.dpdk.org/patch/37149/>>> >> >> Since this patch, IOVA as VA mode uses VA >> addresses, and >> that has >> been backported to earlier releases. I don't think >> there's >> any case >> where we used zero-based addresses any more. >> >> >> But memsegs get the iova based on hugepages physaddr, >> and for VA >> mode that is based on 0x0 as starting point. >> >> And as far as I know, memsegs iovas are what end up >> being used >> for IOMMU mappings and what devices will use. >> >> >> For when physaddrs are available, IOVA as PA mode assigns >> IOVA >> addresses to PA, while IOVA as VA mode assigns IOVA >> addresses to VA >> (both 18.05+ and pre-18.05 as per above patch, which was >> applied to >> pre-18.05 stable releases). >> >> When physaddrs aren't available, IOVA as VA mode assigns IOVA >> addresses to VA, both 18.05+ and pre-18.05, as per above >> patch. >> >> >> This is right. >> >> If physaddrs aren't available and IOVA as PA mode is used, >> then i as >> far as i can remember, even though technically memsegs get >> their >> addresses set to 0x0 onwards, the actual addresses we get in >> memzones etc. are RTE_BAD_IOVA. >> >> >> This is not right. Not sure if this was the intention, but if PA >> mode and physaddrs not available, this code inside >> vfio_type1_dma_map: >> >> if(rte_eal_iova_mode() == RTE_IOVA_VA) >> >> dma_map.iova = dma_map.vaddr; >> >> else >> >> dma_map.iova = ms[i].iova; >> >> >> does the IOMMU mapping using the iovas and not the vaddr, with >> the iovas starting at 0x0. >> >> >> Yep, you're right, apologies. I confused this with no-huge option. >> >> >> So, what do you think about the patchset? Could it be this applied to >> stable versions? >> >> I'll send a patch for current 18.05 code which will have the dma mask and >> the hugepage check, along with changes for doing the mmaps below the dma >> mask limit. >> > > I've looked through the code, it looks OK to me (bar some things like > missing .map file additions and a gratuitous rte_panic :) ). > > There was a patch/discussion not too long ago about DMA masks for some > IOMMU's - perhaps we can also extend this approach to that? > > https://patches.dpdk.org/patch/33192/ > > > I completely missed that patch. It seems it could also be applied for that case adding a dma mask set if it is an emulated VT-d with that 39 bits restriction. I'll take a look at that patch and submit a new patchset including changes for that case. I did also forget the hotplug case where the hugepage checking needs to be invoked. Thanks > >> >> >> -- Thanks, >> Anatoly >> >> >> > > -- > Thanks, > Anatoly >
