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: diff --git a/arch/x86/mm/dump_pagetables.c b/arch/x86/mm/dump_pagetables.c index a12afff146d1..8c04fadc4423 100644 --- a/arch/x86/mm/dump_pagetables.c +++ b/arch/x86/mm/dump_pagetables.c @@ -496,8 +496,8 @@ static inline bool is_hypervisor_range(int idx) * ffff800000000000 - ffff87ffffffffff is reserved for * the hypervisor. */ - return (idx >= pgd_index(__PAGE_OFFSET) - 16) && - (idx < pgd_index(__PAGE_OFFSET)); + return (idx >= pgd_index(LDT_BASE_ADDR) - 16) && + (idx < pgd_index(LDT_BASE_ADDR)); #else return false; #endif diff --git a/arch/x86/xen/mmu_pv.c b/arch/x86/xen/mmu_pv.c index 2c84c6ad8b50..b078a5b0ac91 100644 --- a/arch/x86/xen/mmu_pv.c +++ b/arch/x86/xen/mmu_pv.c @@ -652,7 +652,7 @@ static int __xen_pgd_walk(struct mm_struct *mm, pgd_t *pgd, * will end up making a zero-sized hole and so is a no-op. */ hole_low = pgd_index(USER_LIMIT); - hole_high = pgd_index(PAGE_OFFSET); + hole_high = pgd_index(LDT_BASE_ADDR); nr = pgd_index(limit) + 1; for (i = 0; i < nr; i++) { -- Kirill A. Shutemov
