Re: [Xen-devel] [PATCH 3/7] xen/mmu: Release the Xen provided L4(PGD) back.
From: Stefano Stabellini
Date: Fri Jul 27 2012 - 07:38:12 EST
On Thu, 26 Jul 2012, Konrad Rzeszutek Wilk wrote:
> Since we are not using it and somebody else could use it.
make sense except it is almost entirely rewritten by the following
patch...
> Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
> ---
> arch/x86/xen/mmu.c | 13 +++++++------
> 1 files changed, 7 insertions(+), 6 deletions(-)
>
> diff --git a/arch/x86/xen/mmu.c b/arch/x86/xen/mmu.c
> index a59070b..48bdc9f 100644
> --- a/arch/x86/xen/mmu.c
> +++ b/arch/x86/xen/mmu.c
> @@ -1782,20 +1782,21 @@ void __init xen_setup_kernel_pagetable(pgd_t *pgd, unsigned long max_pfn)
> /* Unpin Xen-provided one */
> pin_pagetable_pfn(MMUEXT_UNPIN_TABLE, PFN_DOWN(__pa(pgd)));
>
> - /* Switch over */
> - pgd = init_level4_pgt;
> -
> /*
> * At this stage there can be no user pgd, and no page
> * structure to attach it to, so make sure we just set kernel
> * pgd.
> */
> xen_mc_batch();
> - __xen_write_cr3(true, __pa(pgd));
> + __xen_write_cr3(true, __pa(init_level4_pgt));
> xen_mc_issue(PARAVIRT_LAZY_CPU);
>
> - memblock_reserve(__pa(xen_start_info->pt_base),
> - xen_start_info->nr_pt_frames * PAGE_SIZE);
> + /* Offset by one page since the original pgd is going bye bye */
> + memblock_reserve(__pa(xen_start_info->pt_base + PAGE_SIZE),
> + (xen_start_info->nr_pt_frames * PAGE_SIZE) - PAGE_SIZE);
> + /* and also RW it so it can actually be used. */
> + set_page_prot(pgd, PAGE_KERNEL);
> + clear_page(pgd);
> }
> #else /* !CONFIG_X86_64 */
> static RESERVE_BRK_ARRAY(pmd_t, initial_kernel_pmd, PTRS_PER_PMD);
> --
> 1.7.7.6
>
>
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> http://lists.xen.org/xen-devel
>
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