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. Hans
