Re: [Xen-devel] [PATCH 4.2] ix86: fix linear page table construction in alloc_l2_table()

[Tim Deegan <tim@xxxxxxx>]

At 15:18 +0000 on 10 Jan (1389363524), Jan Beulich wrote:
> Slot 0 got updated when slot 3 was meant. The mistake was hidden by
> create_pae_xen_mappings() correcting things immediately afterwards
> (i.e. before the new entries could get used the first time).
> 
> Reported-by: CHENG Yueqiang <yqcheng.2008@xxxxxxxxxxxxxxxx>
> Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>

Acked-by: Tim Deegan <tim@xxxxxxx>

> --- a/xen/arch/x86/mm.c
> +++ b/xen/arch/x86/mm.c
> @@ -1488,7 +1488,7 @@ static int alloc_l2_table(struct page_in
>              l2e_write(&pl2e[l2_table_offset(PERDOMAIN_VIRT_START) + i],
>                        l2e_from_page(perdomain_pt_page(d, i),
>                                      __PAGE_HYPERVISOR));
> -        pl2e[l2_table_offset(LINEAR_PT_VIRT_START)] =
> +        pl2e[l2_table_offset(LINEAR_PT_VIRT_START) + 3] =
>              l2e_from_pfn(pfn, __PAGE_HYPERVISOR);
>  #else
>          memcpy(&pl2e[COMPAT_L2_PAGETABLE_FIRST_XEN_SLOT(d)],
> 
> 
> 

> ix86: fix linear page table construction in alloc_l2_table()
> 
> Slot 0 got updated when slot 3 was meant. The mistake was hidden by
> create_pae_xen_mappings() correcting things immediately afterwards
> (i.e. before the new entries could get used the first time).
> 
> Reported-by: CHENG Yueqiang <yqcheng.2008@xxxxxxxxxxxxxxxx>
> Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
> 
> --- a/xen/arch/x86/mm.c
> +++ b/xen/arch/x86/mm.c
> @@ -1488,7 +1488,7 @@ static int alloc_l2_table(struct page_in
>              l2e_write(&pl2e[l2_table_offset(PERDOMAIN_VIRT_START) + i],
>                        l2e_from_page(perdomain_pt_page(d, i),
>                                      __PAGE_HYPERVISOR));
> -        pl2e[l2_table_offset(LINEAR_PT_VIRT_START)] =
> +        pl2e[l2_table_offset(LINEAR_PT_VIRT_START) + 3] =
>              l2e_from_pfn(pfn, __PAGE_HYPERVISOR);
>  #else
>          memcpy(&pl2e[COMPAT_L2_PAGETABLE_FIRST_XEN_SLOT(d)],


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