Re: [Xen-devel] [PATCH 06/11] xen/mmu: For 64-bit do not call xen_map_identity_early

From: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
To: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"xen-devel@lists.xensource.com" <xen-devel@lists.xensource.com>
Subject: Re: [Xen-devel] [PATCH 06/11] xen/mmu: For 64-bit do not call xen_map_identity_early
Date: Fri, 17 Aug 2012 18:41:23 +0100	[thread overview]
Message-ID: <alpine.DEB.2.02.1208171839590.15568@kaball.uk.xensource.com> (raw)
In-Reply-To: <1345133009-21941-7-git-send-email-konrad.wilk@oracle.com>

On Thu, 16 Aug 2012, Konrad Rzeszutek Wilk wrote:
> B/c we do not need it. During the startup the Xen provides
> us with all the memory mapped that we need to function.

Shouldn't we check to make sure that is actually true (I am thinking at
nr_pt_frames)?
Or is it actually stated somewhere in the Xen headers?

> Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
> ---
>  arch/x86/xen/mmu.c |   11 +++++------
>  1 files changed, 5 insertions(+), 6 deletions(-)
> 
> diff --git a/arch/x86/xen/mmu.c b/arch/x86/xen/mmu.c
> index 7247e5a..a59070b 100644
> --- a/arch/x86/xen/mmu.c
> +++ b/arch/x86/xen/mmu.c
> @@ -84,6 +84,7 @@
>   */
>  DEFINE_SPINLOCK(xen_reservation_lock);
>  
> +#ifdef CONFIG_X86_32
>  /*
>   * Identity map, in addition to plain kernel map.  This needs to be
>   * large enough to allocate page table pages to allocate the rest.
> @@ -91,7 +92,7 @@ DEFINE_SPINLOCK(xen_reservation_lock);
>   */
>  #define LEVEL1_IDENT_ENTRIES	(PTRS_PER_PTE * 4)
>  static RESERVE_BRK_ARRAY(pte_t, level1_ident_pgt, LEVEL1_IDENT_ENTRIES);
> -
> +#endif
>  #ifdef CONFIG_X86_64
>  /* l3 pud for userspace vsyscall mapping */
>  static pud_t level3_user_vsyscall[PTRS_PER_PUD] __page_aligned_bss;
> @@ -1628,7 +1629,7 @@ static void set_page_prot(void *addr, pgprot_t prot)
>  	if (HYPERVISOR_update_va_mapping((unsigned long)addr, pte, 0))
>  		BUG();
>  }
> -
> +#ifdef CONFIG_X86_32
>  static void __init xen_map_identity_early(pmd_t *pmd, unsigned long max_pfn)
>  {
>  	unsigned pmdidx, pteidx;
> @@ -1679,7 +1680,7 @@ static void __init xen_map_identity_early(pmd_t *pmd, unsigned long max_pfn)
>  
>  	set_page_prot(pmd, PAGE_KERNEL_RO);
>  }
> -
> +#endif
>  void __init xen_setup_machphys_mapping(void)
>  {
>  	struct xen_machphys_mapping mapping;
> @@ -1765,14 +1766,12 @@ void __init xen_setup_kernel_pagetable(pgd_t *pgd, unsigned long max_pfn)
>  	/* Note that we don't do anything with level1_fixmap_pgt which
>  	 * we don't need. */
>  
> -	/* Set up identity map */
> -	xen_map_identity_early(level2_ident_pgt, max_pfn);
> -
>  	/* Make pagetable pieces RO */
>  	set_page_prot(init_level4_pgt, PAGE_KERNEL_RO);
>  	set_page_prot(level3_ident_pgt, PAGE_KERNEL_RO);
>  	set_page_prot(level3_kernel_pgt, PAGE_KERNEL_RO);
>  	set_page_prot(level3_user_vsyscall, PAGE_KERNEL_RO);
> +	set_page_prot(level2_ident_pgt, PAGE_KERNEL_RO);
>  	set_page_prot(level2_kernel_pgt, PAGE_KERNEL_RO);
>  	set_page_prot(level2_fixmap_pgt, PAGE_KERNEL_RO);
>  
> -- 
> 1.7.7.6
> 
> 
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