On 11/30/18 5:21 PM, Kirill A. Shutemov wrote: > On Fri, Nov 30, 2018 at 02:53:50PM +0000, Hans van Kranenburg wrote: >> On 11/30/18 2:26 PM, Kirill A. Shutemov wrote: >>> On Fri, Nov 30, 2018 at 01:11:56PM +0000, Hans van Kranenburg wrote: >>>> On 11/29/18 4:06 PM, Kirill A. Shutemov wrote: >>>>> On Thu, Nov 29, 2018 at 03:00:45PM +0000, Juergen Gross wrote: >>>>>> On 29/11/2018 15:32, Kirill A. Shutemov wrote: >>>>>>> On Thu, Nov 29, 2018 at 02:24:47PM +0000, Kirill A. Shutemov wrote: >>>>>>>> On Thu, Nov 29, 2018 at 01:35:17PM +0000, Juergen Gross wrote: >>>>>>>>> On 29/11/2018 14:26, Kirill A. Shutemov wrote: >>>>>>>>>> On Thu, Nov 29, 2018 at 09:41:25AM +0000, Juergen Gross wrote: >>>>>>>>>>> On 29/11/2018 02:22, Hans van Kranenburg wrote: >>>>>>>>>>>> Hi, >>>>>>>>>>>> >>>>>>>>>>>> As also seen at: >>>>>>>>>>>> https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=914951 >>>>>>>>>>>> >>>>>>>>>>>> Attached there are two serial console output logs. One is starting with >>>>>>>>>>>> Xen 4.11 (from debian unstable) as dom0, and the other one without Xen. >>>>>>>>>>>> >>>>>>>>>>>> [ 2.085543] BUG: unable to handle kernel paging request at >>>>>>>>>>>> ffff888d9fffc000 >>>>>>>>>>>> [ 2.085610] PGD 200c067 P4D 200c067 PUD 0 >>>>>>>>>>>> [ 2.085674] Oops: 0000 [#1] SMP NOPTI >>>>>>>>>>>> [ 2.085736] CPU: 1 PID: 1 Comm: swapper/0 Not tainted >>>>>>>>>>>> 4.19.0-trunk-amd64 #1 Debian 4.19.5-1~exp1+pvh1 >>>>>>>>>>>> [ 2.085823] Hardware name: HP ProLiant DL360 G7, BIOS P68 05/21/2018 >>>>>>>>>>>> [ 2.085895] RIP: e030:ptdump_walk_pgd_level_core+0x1fd/0x490 >>>>>>>>>>>> [...] >>>>>>>>>>> >>>>>>>>>>> The offending stable commit is 4074ca7d8a1832921c865d250bbd08f3441b3657 >>>>>>>>>>> ("x86/mm: Move LDT remap out of KASLR region on 5-level paging"), this >>>>>>>>>>> is commit d52888aa2753e3063a9d3a0c9f72f94aa9809c15 upstream. >>>>>>>>>>> >>>>>>>>>>> Current upstream kernel is booting fine under Xen, so in general the >>>>>>>>>>> patch should be fine. Using an upstream kernel built from above commit >>>>>>>>>>> (with the then needed Xen fixup patch 1457d8cf7664f34c4ba534) is fine, >>>>>>>>>>> too. >>>>>>>>>>> >>>>>>>>>>> Kirill, are you aware of any prerequisite patch from 4.20 which could be >>>>>>>>>>> missing in 4.19.5? >>>>>>>>>> >>>>>>>>>> I'm not. >>>>>>>>>> >>>>>>>>>> Let me look into this. >>>>>>>>>> >>>>>>>>> >>>>>>>>> What is making me suspicious is the failure happening just after >>>>>>>>> releasing the init memory. Maybe there is an access to .init.data >>>>>>>>> segment or similar? The native kernel booting could be related to the >>>>>>>>> usage of 2M mappings not being available in a PV-domain. >>>>>>>> >>>>>>>> Ahh.. Could you test this: >>>>>>>> >>>>>>>> diff --git a/arch/x86/mm/dump_pagetables.c b/arch/x86/mm/dump_pagetables.c >>>>>>>> index a12afff146d1..7dec63ec7aab 100644 >>>>>>>> --- a/arch/x86/mm/dump_pagetables.c >>>>>>>> +++ b/arch/x86/mm/dump_pagetables.c >>>>>>>> @@ -496,7 +496,7 @@ static inline bool is_hypervisor_range(int idx) >>>>>>>> * ffff800000000000 - ffff87ffffffffff is reserved for >>>>>>>> * the hypervisor. >>>>>>>> */ >>>>>>>> - return (idx >= pgd_index(__PAGE_OFFSET) - 16) && >>>>>>>> + return (idx >= pgd_index(__PAGE_OFFSET) - 17) && >>>>>>>> (idx < pgd_index(__PAGE_OFFSET)); >>>>>>>> #else >>>>>>>> return false; >>>>>>> >>>>>>> Or, better, this: >>>>>> >>>>>> That makes it boot again! >>>>>> >>>>>> Any idea why upstream doesn't need it? >>>>> >>>>> Nope. >>>>> >>>>> I'll prepare a proper fix. >>>>> >>>> >>>> Thanks for looking into this. >>>> >>>> In the meantime, I applied the "Or, better, this" change, and my dom0 >>>> boots again. >>>> >>>> FYI, boot log now: (paste 90d valid) >>>> https://paste.debian.net/plainh/48940826 >>> >>> I forgot to CC you: >>> >>> https://lkml.kernel.org/r/20181130121131.g3xvlvixv7mvlr7b@xxxxxxxxxxxxxxxxxx >>> >>> Please give it a try. >> >> I'm not in that thread, so my response here... >> >> You paste a v2-like patch into 'Re: [PATCH 1/2]'. Juergen says: >> s/LDT_PGD_ENTRY/GUARD_HOLE_PGD_ENTRY/, then you say Ughh.., change it to >> GUARD_HOLE_ENTRY, which does not exist, and then get a Reviewed-by from >> Juergen. >> >> I guess it has to be GUARD_HOLE_PGD_ENTRY after all... >> >> arch/x86/include/asm/pgtable_64_types.h:116:31: error: >> 'GUARD_HOLE_ENTRY' undeclared (first use in this function); did you mean >> 'GUARD_HOLE_PGD_ENTRY'? >> >> I'll test that instead. > > Yes, thank you. It was a long week... :/ > > Let me know if it works. I'll repost the fixed version with your > Tested-by. Ok. It boots fine as Xen dom0. \o/ You can use "Hans van Kranenburg <hans.van.kranenburg@xxxxxxxxxx>" (lowercase please) for reported/tested in the real v2. Hans
