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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] RE: Troubles running Xen on Raspberry Pi 4 with 5.6.1 DomU
On Wed, 6 May 2020, Peng Fan wrote: > > Subject: Re: Troubles running Xen on Raspberry Pi 4 with 5.6.1 DomU > > > > On 06.05.20 00:34, Stefano Stabellini wrote: > > > + Boris, Jürgen > > > > > > See the crash Roman is seeing booting dom0 on the Raspberry Pi. It is > > > related to the recent xen dma_ops changes. Possibly the same thing > > > reported by Peng here: > > Yes. It is same issue. > > > > > > > https://eur01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fmarc > > > .info%2F%3Fl%3Dlinux-kernel%26m%3D158805976230485%26w%3D2&am > > p;data=02% > > > > > 7C01%7Cpeng.fan%40nxp.com%7Cab98b2db94484141a8ad08d7f1803372%7 > > C686ea1d > > > > > 3bc2b4c6fa92cd99c5c301635%7C0%7C0%7C637243405233572354&sd > > ata=0Yr5h > > > Rg4%2FuApsBpTwIIL4StZU%2FUA55oP5Lfnfmtj4Hg%3D&reserved=0 > > > > > > An in-depth analysis below. > > > > > > > > > On Mon, 4 May 2020, Roman Shaposhnik wrote: > > >>>> [ 2.534292] Unable to handle kernel paging request at virtual > > >>>> address 000000000026c340 > > >>>> [ 2.542373] Mem abort info: > > >>>> [ 2.545257] ESR = 0x96000004 > > >>>> [ 2.548421] EC = 0x25: DABT (current EL), IL = 32 bits > > >>>> [ 2.553877] SET = 0, FnV = 0 > > >>>> [ 2.557023] EA = 0, S1PTW = 0 > > >>>> [ 2.560297] Data abort info: > > >>>> [ 2.563258] ISV = 0, ISS = 0x00000004 > > >>>> [ 2.567208] CM = 0, WnR = 0 > > >>>> [ 2.570294] [000000000026c340] user address but active_mm is > > swapper > > >>>> [ 2.576783] Internal error: Oops: 96000004 [#1] SMP > > >>>> [ 2.581784] Modules linked in: > > >>>> [ 2.584950] CPU: 3 PID: 135 Comm: kworker/3:1 Not tainted > > 5.6.1-default #9 > > >>>> [ 2.591970] Hardware name: Raspberry Pi 4 Model B (DT) > > >>>> [ 2.597256] Workqueue: events deferred_probe_work_func > > >>>> [ 2.602509] pstate: 60000005 (nZCv daif -PAN -UAO) > > >>>> [ 2.607431] pc : xen_swiotlb_free_coherent+0x198/0x1d8 > > >>>> [ 2.612696] lr : dma_free_attrs+0x98/0xd0 > > >>>> [ 2.616827] sp : ffff800011db3970 > > >>>> [ 2.620242] x29: ffff800011db3970 x28: 00000000000f7b00 > > >>>> [ 2.625695] x27: 0000000000001000 x26: ffff000037b68410 > > >>>> [ 2.631129] x25: 0000000000000001 x24: 00000000f7b00000 > > >>>> [ 2.636583] x23: 0000000000000000 x22: 0000000000000000 > > >>>> [ 2.642017] x21: ffff800011b0d000 x20: ffff80001179b548 > > >>>> [ 2.647461] x19: ffff000037b68410 x18: 0000000000000010 > > >>>> [ 2.652905] x17: ffff000035d66a00 x16: 00000000deadbeef > > >>>> [ 2.658348] x15: ffffffffffffffff x14: ffff80001179b548 > > >>>> [ 2.663792] x13: ffff800091db37b7 x12: ffff800011db37bf > > >>>> [ 2.669236] x11: ffff8000117c7000 x10: ffff800011db3740 > > >>>> [ 2.674680] x9 : 00000000ffffffd0 x8 : ffff80001071e980 > > >>>> [ 2.680124] x7 : 0000000000000132 x6 : ffff80001197a6ab > > >>>> [ 2.685568] x5 : 0000000000000000 x4 : 0000000000000000 > > >>>> [ 2.691012] x3 : 00000000f7b00000 x2 : fffffdffffe00000 > > >>>> [ 2.696465] x1 : 000000000026c340 x0 : 000002000046c340 > > >>>> [ 2.701899] Call trace: > > >>>> [ 2.704452] xen_swiotlb_free_coherent+0x198/0x1d8 > > >>>> [ 2.709367] dma_free_attrs+0x98/0xd0 > > >>>> [ 2.713143] rpi_firmware_property_list+0x1e4/0x240 > > >>>> [ 2.718146] rpi_firmware_property+0x6c/0xb0 > > >>>> [ 2.722535] rpi_firmware_probe+0xf0/0x1e0 > > >>>> [ 2.726760] platform_drv_probe+0x50/0xa0 > > >>>> [ 2.730879] really_probe+0xd8/0x438 > > >>>> [ 2.734567] driver_probe_device+0xdc/0x130 > > >>>> [ 2.738870] __device_attach_driver+0x88/0x108 > > >>>> [ 2.743434] bus_for_each_drv+0x78/0xc8 > > >>>> [ 2.747386] __device_attach+0xd4/0x158 > > >>>> [ 2.751337] device_initial_probe+0x10/0x18 > > >>>> [ 2.755649] bus_probe_device+0x90/0x98 > > >>>> [ 2.759590] deferred_probe_work_func+0x88/0xd8 > > >>>> [ 2.764244] process_one_work+0x1f0/0x3c0 > > >>>> [ 2.768369] worker_thread+0x138/0x570 > > >>>> [ 2.772234] kthread+0x118/0x120 > > >>>> [ 2.775571] ret_from_fork+0x10/0x18 > > >>>> [ 2.779263] Code: d34cfc00 f2dfbfe2 d37ae400 8b020001 > > (f8626800) > > >>>> [ 2.785492] ---[ end trace 4c435212e349f45f ]--- > > >>>> [ 2.793340] usb 1-1: New USB device found, idVendor=2109, > > >>>> idProduct=3431, bcdDevice= 4.20 > > >>>> [ 2.801038] usb 1-1: New USB device strings: Mfr=0, Product=1, > > SerialNumber=0 > > >>>> [ 2.808297] usb 1-1: Product: USB2.0 Hub > > >>>> [ 2.813710] hub 1-1:1.0: USB hub found > > >>>> [ 2.817117] hub 1-1:1.0: 4 ports detected > > >>>> > > >>>> This is bailing out right here: > > >>>> > > >>>> https://eur01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fg > > >>>> > > it.kernel.org%2Fpub%2Fscm%2Flinux%2Fkernel%2Fgit%2Fstable%2Flinux.g > > >>>> > > it%2Ftree%2Fdrivers%2Ffirmware%2Fraspberrypi.c%3Fh%3Dv5.6.1%23n125 > > & > > >>>> > > amp;data=02%7C01%7Cpeng.fan%40nxp.com%7Cab98b2db94484141a8ad0 > > 8d7f18 > > >>>> > > 03372%7C686ea1d3bc2b4c6fa92cd99c5c301635%7C0%7C0%7C6372434052 > > 335723 > > >>>> > > 54&sdata=h1dyHkb%2FsifUqH3Z0m3uIIcqUhXVwhHS%2Ft%2FVvig%2Fo > > u4%3D > > >>>> &reserved=0 > > >>>> > > >>>> FYIW (since I modified the source to actually print what was > > >>>> returned right before it bails) we get: > > >>>> buf[1] == 0x800000004 > > >>>> buf[2] == 0x00000001 > > >>>> > > >>>> Status 0x800000004 is of course suspicious since it is not even listed > > here: > > >>>> > > >>>> https://eur01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fg > > >>>> > > it.kernel.org%2Fpub%2Fscm%2Flinux%2Fkernel%2Fgit%2Fstable%2Flinux.g > > >>>> > > it%2Ftree%2Finclude%2Fsoc%2Fbcm2835%2Fraspberrypi-firmware.h%23n14 > > & > > >>>> > > amp;data=02%7C01%7Cpeng.fan%40nxp.com%7Cab98b2db94484141a8ad0 > > 8d7f18 > > >>>> > > 03372%7C686ea1d3bc2b4c6fa92cd99c5c301635%7C0%7C0%7C6372434052 > > 335723 > > >>>> > > 54&sdata=3yMm%2FujHCVf%2FigpNLE8hcBWVcvdGrZGv5TuqeMzMV0 > > U%3D& > > >>>> ;reserved=0 > > >>>> > > >>>> So it appears that this DMA request path is somehow busted and it > > >>>> would be really nice to figure out why. > > >>> > > >>> You have actually discovered a genuine bug in the recent xen dma > > >>> rework in Linux. Congrats :-) > > >> > > >> Nice! ;-) > > >> > > >>> I am doing some guesswork here, but from what I read in the thread > > >>> and the information in this email I think this patch might fix the > > >>> issue. > > >>> If it doesn't fix the issue please add a few printks in > > >>> drivers/xen/swiotlb-xen.c:xen_swiotlb_free_coherent and please let > > >>> me know where exactly it crashes. > > >>> > > >>> > > >>> diff --git a/include/xen/arm/page-coherent.h > > >>> b/include/xen/arm/page-coherent.h index b9cc11e887ed..ff4677ed9788 > > >>> 100644 > > >>> --- a/include/xen/arm/page-coherent.h > > >>> +++ b/include/xen/arm/page-coherent.h > > >>> @@ -8,12 +8,17 @@ > > >>> static inline void *xen_alloc_coherent_pages(struct device *hwdev, > > size_t size, > > >>> dma_addr_t *dma_handle, gfp_t flags, unsigned > > long attrs) > > >>> { > > >>> + void *cpu_addr; > > >>> + if (dma_alloc_from_dev_coherent(hwdev, size, dma_handle, > > &cpu_addr)) > > >>> + return cpu_addr; > > >>> return dma_direct_alloc(hwdev, size, dma_handle, flags, > > attrs); > > >>> } > > >>> > > >>> static inline void xen_free_coherent_pages(struct device *hwdev, > > size_t size, > > >>> void *cpu_addr, dma_addr_t dma_handle, > > unsigned long attrs) > > >>> { > > >>> + if (dma_release_from_dev_coherent(hwdev, get_order(size), > > cpu_addr)) > > >>> + return; > > >>> dma_direct_free(hwdev, size, cpu_addr, dma_handle, attrs); > > >>> } > > >> > > >> Applied the patch, but it didn't help and after printk's it turns out > > >> it surprisingly crashes right inside this (rather convoluted if you > > >> ask me) if statement: > > >> > > >> https://eur01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgit > > >> .kernel.org%2Fpub%2Fscm%2Flinux%2Fkernel%2Fgit%2Fstable%2Flinux.gi > > t%2 > > >> > > Ftree%2Fdrivers%2Fxen%2Fswiotlb-xen.c%3Fh%3Dv5.6.1%23n349&dat > > a=02 > > >> %7C01%7Cpeng.fan%40nxp.com%7Cab98b2db94484141a8ad08d7f18033 > > 72%7C686ea > > >> > > 1d3bc2b4c6fa92cd99c5c301635%7C0%7C0%7C637243405233572354& > > sdata=Fu > > >> > > BWGAEg%2FkbsnYIIGHmiICTqy%2BcgZs7V%2BMneJum%2BTts%3D&res > > erved=0 > > >> > > >> So it makes sense that the patch didn't help -- we never hit that > > >> xen_free_coherent_pages. > > > > > > The crash happens here: > > > > > > if (!WARN_ON((dev_addr + size - 1 > dma_mask) || > > > range_straddles_page_boundary(phys, size)) && > > > TestClearPageXenRemapped(virt_to_page(vaddr))) > > > xen_destroy_contiguous_region(phys, order); > > > > > > I don't know exactly what is causing the crash. Is it the WARN_ON > > somehow? > > > Is it TestClearPageXenRemapped? Neither should cause a crash in theory. > > > > > > > > > But I do know that there are problems with that if statement on ARM. > > > It can trigger for one of the following conditions: > > > > > > 1) dev_addr + size - 1 > dma_mask > > > 2) range_straddles_page_boundary(phys, size) > > > diff --git a/drivers/xen/swiotlb-xen.c b/drivers/xen/swiotlb-xen.c > index bd3a10dfac15..33b027cb0b2a 100644 > --- a/drivers/xen/swiotlb-xen.c > +++ b/drivers/xen/swiotlb-xen.c > @@ -346,6 +346,7 @@ xen_swiotlb_free_coherent(struct device *hwdev, size_t > size, void *vaddr, > /* Convert the size to actually allocated. */ > size = 1UL << (order + XEN_PAGE_SHIFT); > > + printk("%x %x %px %x %px\n", dev_addr + size - 1 > dma_mask, > range_straddles_page_boundary(phys, size), virt_to_page(vaddr), phys, vaddr); > if (!WARN_ON((dev_addr + size - 1 > dma_mask) || > range_straddles_page_boundary(phys, size)) && > TestClearPageXenRemapped(virt_to_page(vaddr))) > > > In my case: > 0 0 0000000000271f40 bc000000 ffff800011c7d000 > > > The alloc path in my side: > 314 phys = *dma_handle; > 315 dev_addr = xen_phys_to_bus(phys); > 316 if (((dev_addr + size - 1 <= dma_mask)) && > 317 !range_straddles_page_boundary(phys, size)) > 318 *dma_handle = dev_addr; > > So I am confused why the free path needs clear xen remap. Thanks this is useful information, now I understand what is going on. In your case it shouldn't take the if path in xen_swiotlb_free_coherent at all, but still should evaluate the if condition. So the if would return false for you, but you can't finish evaluating the if because virt_to_page causes a crash.
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