[Xen-devel] Re: [PATCH] xen: convert pt_base to a physical address before converting to PFN

[Jeremy Fitzhardinge <jeremy@xxxxxxxx>]

Ian Campbell wrote:
> (applies to xen/dom0/hackery)
>   
Oops, thanks.   Perils of hand-editing patches...

   J
> Otherwise xen_map_identity_early can try and creating a mapping which extends
> too far into invalid PFN territory creating invalid page tables:
>   mapping kernel into physical memory
>   (XEN) mm.c:703:d50 Non-privileged (50) attempt to map I/O space 7fffffff
>   (XEN) mm.c:1093:d50 Failure in alloc_l1_table: entry 0
>   (XEN) mm.c:2008:d50 Error while validating mfn de047 (pfn 497) for type 
> 2000000000000000: caf=8000000000000003 taf=2000000000000001
>   (XEN) mm.c:770:d50 Attempt to create linear p.t. with write perms
>   (XEN) mm.c:1253:d50 Failure in alloc_l2_table: entry 48
>   (XEN) mm.c:2008:d50 Error while validating mfn de074 (pfn 46a) for type 
> 4400000000000000: caf=8000000000000003 taf=4400000000000001
>   (XEN) mm.c:1342:d50 Failure in alloc_l3_table: entry 3
>   (XEN) mm.c:2008:d50 Error while validating mfn df405 (pfn 3d9) for type 
> 6000000000000000: caf=8000000000000003 taf=6000000000000001
>   (XEN) mm.c:848:d50 Attempt to create linear p.t. with write perms
>   (XEN) mm.c:2375:d50 Error while installing new compat baseptr df405
>
> Signed-off-by: Ian Campbell <ian.campbell@xxxxxxxxxx>
> ---
>  arch/x86/xen/mmu.c |    4 ++--
>  1 files changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/arch/x86/xen/mmu.c b/arch/x86/xen/mmu.c
> index 6c24275..375548f 100644
> --- a/arch/x86/xen/mmu.c
> +++ b/arch/x86/xen/mmu.c
> @@ -1819,7 +1819,7 @@ __init pgd_t *xen_setup_kernel_pagetable(pgd_t *pgd,
>         l2 = m2v(l3[pud_index(__START_KERNEL_map + PMD_SIZE)].pud);
>         memcpy(level2_fixmap_pgt, l2, sizeof(pmd_t) * PTRS_PER_PMD);
>  
> -	max_pfn_mapped = PFN_DOWN(xen_start_info->pt_base +
> +       max_pfn_mapped = PFN_DOWN(__pa(xen_start_info->pt_base) +
>                                   xen_start_info->nr_pt_frames * PAGE_SIZE +
>                                   512*1024);
>  
> @@ -1871,7 +1871,7 @@ __init pgd_t *xen_setup_kernel_pagetable(pgd_t *pgd,
>  
>  	level2_kernel_pgt = extend_brk(PAGE_SIZE, PAGE_SIZE);
>  
> -	max_pfn_mapped = PFN_DOWN(xen_start_info->pt_base +
> +       max_pfn_mapped = PFN_DOWN(__pa(xen_start_info->pt_base) +
>                                   xen_start_info->nr_pt_frames * PAGE_SIZE +
>                                   512*1024);
>  
>   
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