Re: [PATCH 3/6] xen/x86/pvh: Properly set page tables for 32-bit PVH guests
From: Konrad Rzeszutek Wilk
Date: Tue Jul 07 2015 - 15:31:50 EST
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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