Re: [Qemu-devel] [PATCH] Fix mask of pte index

From: Jesse Larrew <jlarrew@linux.vnet.ibm.com>
To: Qiao Nuohan <qiaonuohan@cn.fujitsu.com>
Cc: aliguori@us.ibm.com, qemu-devel@nongnu.org
Subject: Re: [Qemu-devel] [PATCH] Fix mask of pte index
Date: Tue, 21 May 2013 01:16:14 -0500	[thread overview]
Message-ID: <519B112E.7040100@linux.vnet.ibm.com> (raw)
In-Reply-To: <1369105221-26307-1-git-send-email-qiaonuohan@cn.fujitsu.com>

On 05/20/2013 10:00 PM, Qiao Nuohan wrote:
> Function walk_pte needs pte index to calculate virtual address. However, pte
> index of PAE paging or IA-32e paging is 9 bit, so the mask should be 0x1ff.
> ---
>  target-i386/arch_memory_mapping.c |    2 +-
>  1 files changed, 1 insertions(+), 1 deletions(-)
> 
> diff --git a/target-i386/arch_memory_mapping.c b/target-i386/arch_memory_mapping.c
> index 844893f..a2eb7e7 100644
> --- a/target-i386/arch_memory_mapping.c
> +++ b/target-i386/arch_memory_mapping.c
> @@ -38,7 +38,7 @@ static void walk_pte(MemoryMappingList *list, hwaddr pte_start_addr,
>              continue;
>          }
> 
> -        start_vaddr = start_line_addr | ((i & 0x1fff) << 12);
> +        start_vaddr = start_line_addr | ((i & 0x1ff) << 12);
>          memory_mapping_list_add_merge_sorted(list, start_paddr,
>                                               start_vaddr, 1 << 12);
>      }
> 

Verified that this agrees with the spec for IA-32e/PAE paging. Note that
walk_pte2() is correct; only walk_pte() has the typo.

Reviewed by: Jesse Larrew <jlarrew@linux.vnet.ibm.com>

Jesse Larrew
Software Engineer, KVM Team
IBM Linux Technology Center
Phone: (512) 973-2052 (T/L: 363-2052)
jlarrew@linux.vnet.ibm.com