On 01/07/18 23:26, Michael Young wrote:
> On Sun, 1 Jul 2018, M A Young wrote:
>
>> I get (with kernel-4.17.3-200.fc28.x86_64 which is a bit easier)
>>
>> rip: ffffffff81062330 native_irq_disable
>> flags: 00000246 i z p
>> rsp: ffffffff82203d90
>> rax: 0000000000000246 rcx: 0000000000000000 rdx: 0000000000000000
>> rbx: 00000000ffffffff rsi: 00000000ffffffff rdi: 0000000000000000
>> rbp: 0000000000000000 r8: ffffffff820bb698 r9: ffffffff82203e38
>> r10: 0000000000000000 r11: 0000000000000000 r12: 0000000000000000
>> r13: ffffffff820bb698 r14: ffffffff82203e38 r15: 0000000000000000
>> cs: e033 ss: e02b ds: 0000 es: 0000
>> fs: 0000 @ 0000000000000000
>> gs: 0000 @ ffffffff82731000/0000000000000000 __init_begin/
>> Code (instr addr ffffffff81062330)
>> 00 00 00 00 00 57 9d c3 0f 1f 00 66 2e 0f 1f 84 00 00 00 00 00 <fa> c3 0f
>> 1f 40 00 66 2e 0f 1f 84
>>
>>
>> Stack:
>> 0000000000000000 0000000000000000 0000000000000000 ffffffff81062330
>> 000000010000e030 0000000000010046 ffffffff82203dd8 000000000000e02b
>> 0000000000000246 ffffffff8110dff9 0000000000000000 0000000000000246
>> 0000000000000000 0000000000000000 ffffffff820a6cd0 ffffffff82203e88
>> ffffffff82739000 8000000000000061 0000000000000000 0000000000000000
>>
>> Call Trace:
>> [<ffffffff81062330>] native_irq_disable <--
>> ffffffff82203da8: [<ffffffff81062330>] native_irq_disable
>> ffffffff82203dd8: [<ffffffff8110dff9>] vprintk_emit+0xe9
>> ffffffff82203e30: [<ffffffff8110ec96>] printk+0x58
>> ffffffff82203e90: [<ffffffff810ac970>] __warn_printk+0x46
>> ffffffff82203ef8: [<ffffffff8275db62>] xen_load_gdt_boot+0x108
>> ffffffff82203f28: [<ffffffff81037c70>] load_direct_gdt+0x30
>> ffffffff82203f40: [<ffffffff81037f08>] switch_to_new_gdt+0x8
>> ffffffff82203f48: [<ffffffff8102aae0>] x86_init_noop
>> ffffffff82203f50: [<ffffffff8275dc8c>] xen_start_kernel+0xed
>
> I think the crash is triggered by the code
>
> static inline pgprotval_t check_pgprot(pgprot_t pgprot)
> {
> pgprotval_t massaged_val = massage_pgprot(pgprot);
>
> /* mmdebug.h can not be included here because of dependencies */
> #ifdef CONFIG_DEBUG_VM
> WARN_ONCE(pgprot_val(pgprot) != massaged_val,
> "attempted to set unsupported pgprot: %016llx "
> "bits: %016llx supported: %016llx\n",
> (u64)pgprot_val(pgprot),
> (u64)pgprot_val(pgprot) ^ massaged_val,
> (u64)__supported_pte_mask);
> #endif
>
> return massaged_val;
> }
>
> static inline pte_t pfn_pte(unsigned long page_nr, pgprot_t pgprot)
> {
> return __pte(((phys_addr_t)page_nr << PAGE_SHIFT) |
> check_pgprot(pgprot));
> }
>
> in arch/x86/include/asm/pgtable.h which is inlined into
> xen_load_gdt_boot by via pfn_pte
>
> In 4.16 the equivalent code was
>
> static inline pte_t pfn_pte(unsigned long page_nr, pgprot_t pgprot)
> {
> return __pte(((phys_addr_t)page_nr << PAGE_SHIFT) |
> massage_pgprot(pgprot));
> }
There are two problems here:
1. pv_irq_ops hasn't been setup early enough, so the printk() will use
native_irq_disable() instead of the Xen variant.
2. For PV domains the default kernel pte should not include the global
bit. Repairing this issue will avoid the WARN_ONCE() above.
I'll send two patches soon to fix the issues.
Juergen
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