Re: [Xen-devel] crash on boot with 4.6.1 on fedora 24

[Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx>]

On 05/26/2016 06:24 AM, David Vrabel wrote:
>> @@ -1577,10 +1577,10 @@ static pte_t __init mask_rw_pte(pte_t *ptep,
>> pte_t pte)
>>       * page tables for mapping the p2m list, too, and page tables MUST be
>>       * mapped read-only.
>>       */
>> -    pfn = pte_pfn(pte);
>> +    pfn = (pte & PTE_PFN_MASK) >> PAGE_SHIFT;
>>      if (pfn >= xen_start_info->first_p2m_pfn &&
>>          pfn < xen_start_info->first_p2m_pfn + xen_start_info->nr_p2m_frames)
>> -            pte = __pte_ma(pte_val_ma(pte) & ~_PAGE_RW);
>> +            pte &= ~_PAGE_RW;
>>
>>      return pte;
>>  }
>> @@ -1600,13 +1600,26 @@ static pte_t __init mask_rw_pte(pte_t *ptep,
>> pte_t pte)
>>   * so always write the PTE directly and rely on Xen trapping and
>>   * emulating any updates as necessary.
>>   */
>> +__visible __init pte_t xen_make_pte_init(pteval_t pte)
>> +{
>> +#ifdef CONFIG_X86_64
>> +    pte = mask_rw_pte(pte);
>> +#endif


Won't make_pte() be called on 32-bit as well? (And if yes then we can
get rid of xen_set_pte_init())

(Also there were build warnings about xen_make_pte_init() being in wrong
section because PV_CALLEE_SAVE is not __init).

-boris



>> +    pte = pte_pfn_to_mfn(pte);
>> +
>> +    if ((pte & PTE_PFN_MASK) >> PAGE_SHIFT == INVALID_P2M_ENTRY)
>> +            pte = 0;
>> +
>> +    return native_make_pte(pte);
>> +}
>> +PV_CALLEE_SAVE_REGS_THUNK(xen_make_pte_init);
>> +
>>  static void __init xen_set_pte_init(pte_t *ptep, pte_t pte)
>>  {
>> +#ifdef CONFIG_X86_32
>>      if (pte_mfn(pte) != INVALID_P2M_ENTRY)
>>              pte = mask_rw_pte(ptep, pte);
>> -    else
>> -            pte = __pte_ma(0);
>> -
>> +#endif
>>      native_set_pte(ptep, pte);
>>  }
>>
>> @@ -2407,6 +2420,7 @@ static void __init xen_post_allocator_init(void)
>>      pv_mmu_ops.alloc_pud = xen_alloc_pud;
>>      pv_mmu_ops.release_pud = xen_release_pud;
>>  #endif
>> +    pv_mmu_ops.make_pte = PV_CALLEE_SAVE(xen_make_pte);
>>
>>  #ifdef CONFIG_X86_64
>>      pv_mmu_ops.write_cr3 = &xen_write_cr3;
>> @@ -2455,7 +2469,7 @@ static const struct pv_mmu_ops xen_mmu_ops
>> __initconst = {
>>      .pte_val = PV_CALLEE_SAVE(xen_pte_val),
>>      .pgd_val = PV_CALLEE_SAVE(xen_pgd_val),
>>
>> -    .make_pte = PV_CALLEE_SAVE(xen_make_pte),
>> +    .make_pte = PV_CALLEE_SAVE(xen_make_pte_init),
>>      .make_pgd = PV_CALLEE_SAVE(xen_make_pgd),
>>
>>  #ifdef CONFIG_X86_PAE
>>
>
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