Re: [Xen-devel] [PATCH 3/6] xen/x86/pvh: Properly set page tables for 32-bit PVH guests

[Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>]

On Mon, Jul 06, 2015 at 11:34:22PM -0400, Boris Ostrovsky wrote:
> 32-bit PVH guests don't want to write-protect/pin page tables.
> 
> Signed-off-by: Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx>

Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
> ---
>  arch/x86/xen/mmu.c | 22 +++++++++++++---------
>  1 file changed, 13 insertions(+), 9 deletions(-)
> 
> diff --git a/arch/x86/xen/mmu.c b/arch/x86/xen/mmu.c
> index dd151b2..b473df8 100644
> --- a/arch/x86/xen/mmu.c
> +++ b/arch/x86/xen/mmu.c
> @@ -1762,8 +1762,9 @@ void __init xen_setup_machphys_mapping(void)
>               machine_to_phys_nr = MACH2PHYS_NR_ENTRIES;
>       }
>  #ifdef CONFIG_X86_32
> -     WARN_ON((machine_to_phys_mapping + (machine_to_phys_nr - 1))
> -             < machine_to_phys_mapping);
> +     if (!xen_feature(XENFEAT_auto_translated_physmap))
> +             WARN_ON((machine_to_phys_mapping + (machine_to_phys_nr - 1))
> +                     < machine_to_phys_mapping);
>  #endif
>  }
>  
> @@ -1958,15 +1959,18 @@ void __init xen_setup_kernel_pagetable(pgd_t *pgd, 
> unsigned long max_pfn)
>       initial_page_table[KERNEL_PGD_BOUNDARY] =
>               __pgd(__pa(initial_kernel_pmd) | _PAGE_PRESENT);
>  
> -     set_page_prot(initial_kernel_pmd, PAGE_KERNEL_RO);
> -     set_page_prot(initial_page_table, PAGE_KERNEL_RO);
> -     set_page_prot(empty_zero_page, PAGE_KERNEL_RO);
> +     if (!xen_feature(XENFEAT_auto_translated_physmap)) {
> +             set_page_prot(initial_kernel_pmd, PAGE_KERNEL_RO);
> +             set_page_prot(initial_page_table, PAGE_KERNEL_RO);
> +             set_page_prot(empty_zero_page, PAGE_KERNEL_RO);
>  
> -     pin_pagetable_pfn(MMUEXT_UNPIN_TABLE, PFN_DOWN(__pa(pgd)));
> +             pin_pagetable_pfn(MMUEXT_UNPIN_TABLE, PFN_DOWN(__pa(pgd)));
>  
> -     pin_pagetable_pfn(MMUEXT_PIN_L3_TABLE,
> -                       PFN_DOWN(__pa(initial_page_table)));
> -     xen_write_cr3(__pa(initial_page_table));
> +             pin_pagetable_pfn(MMUEXT_PIN_L3_TABLE,
> +                               PFN_DOWN(__pa(initial_page_table)));
> +             xen_write_cr3(__pa(initial_page_table));
> +     } else
> +             native_write_cr3(__pa(initial_page_table));
>  
>       memblock_reserve(__pa(xen_start_info->pt_base),
>                        xen_start_info->nr_pt_frames * PAGE_SIZE);
> -- 
> 1.8.1.4
> 

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