On 31/07/2019 20:35, Roman Shaposhnik wrote: > On Wed, Jul 31, 2019 at 1:43 AM Roger Pau Monné <roger....@citrix.com> wrote: >> On Wed, Jul 31, 2019 at 10:36:31AM +0200, Roger Pau Monné wrote: >>> On Tue, Jul 30, 2019 at 10:55:24AM -0700, Roman Shaposhnik wrote: >>>> Sorry -- got a bit distracted yesterday. Attached is the log with only >>>> your latest patch attached. Interestingly enough the box booted fine >>>> without screen artifacts. So I guess we're getting closer... >>>> >>>> Thanks for all the help! >>> That's quite weird, there's no functional changes between the >>> previous patches and this one, the only difference is that this patch >>> has more verbose output. >>> >>> Are you sure you didn't have any local patches on top of Xen that >>> could explain this difference in behaviour? >> FWIW, can you please try the plain patch again: >> >> https://lists.xenproject.org/archives/html/xen-devel/2019-07/msg01547.html >> >> And report back? >> >> I would like to get this committed ASAP if it does fix your issue. > I'd like to say that it did -- but I tried it again just now and it > still garbled screen and tons of: > > (XEN) printk: 26665 messages suppressed. > (XEN) [VT-D]DMAR:[DMA Read] Request device [0000:00:02.0] fault addr > 8e14c000, iommu reg = ffff82c0008de000 > > I'm very much confused by what's going on, but it seems that's the > case -- adding those debug print statements make the issue go away > > Here are the patches that are being applied: > NOT WORKING: > https://github.com/rvs/eve/blob/xen-bug/pkg/xen/01-iommu-mappings.patch > > WORKING: > https://github.com/rvs/eve/blob/a1291fcd4e669df2a63285afb5e8b4841f45c1c8/pkg/xen/01-iommu-mappings.patch > > At this point I'm really not sure what's going on.
Ok. seeing as you've double checked this, the mystery deepens. My bet is on the intel_iommu_lookup_page() call having side effects[1]. If you take out the debugging in the middle of the loop in rmrr_identity_mapping(), does the problem reproduce again? ~Andrew [1] Looking at the internals of addr_to_dma_page_maddr(), it does 100% more memory allocation and higher-level PTE construction than looks wise for what is supposed to be a getter. _______________________________________________ Xen-devel mailing list Xen-devel@lists.xenproject.org https://lists.xenproject.org/mailman/listinfo/xen-devel
