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

[Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>]

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@oracle.com>

Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
> ---
>  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
>