Re: [Qemu-devel] [PATCH] fix bits 39:32 of the final physical address when using 4M page

["Andreas Färber" <afaerber@suse.de>]

Am 07.01.2013 13:06, schrieb Markus Armbruster:
> Wen Congyang <wency@cn.fujitsu.com> writes:
> 
>> ((pde & 0x1fe000) << 19) is the bits 39:32 of the final physical address, and
>> we shouldn't use unit32_t to calculate it. Convert the type to hwaddr to fix
>> this problem.
> 
> Spotted by Coverity.
> 
>> Signed-off-by: Wen Congyang <wency@cn.fujitsu.com>
>>
>> ---
>>  target-i386/arch_memory_mapping.c | 11 ++++++++---
>>  1 file changed, 8 insertions(+), 3 deletions(-)
>>
>> diff --git a/target-i386/arch_memory_mapping.c b/target-i386/arch_memory_mapping.c
>> index c6c7874..844893f 100644
>> --- a/target-i386/arch_memory_mapping.c
>> +++ b/target-i386/arch_memory_mapping.c
>> @@ -115,7 +115,7 @@ static void walk_pde2(MemoryMappingList *list,
>>                        hwaddr pde_start_addr, int32_t a20_mask,
>>                        bool pse)
>>  {
>> -    hwaddr pde_addr, pte_start_addr, start_paddr;
>> +    hwaddr pde_addr, pte_start_addr, start_paddr, high_paddr;
>>      uint32_t pde;
>>      target_ulong line_addr, start_vaddr;
>>      int i;
>> @@ -130,8 +130,13 @@ static void walk_pde2(MemoryMappingList *list,
>>  
>>          line_addr = (((unsigned int)i & 0x3ff) << 22);
>>          if ((pde & PG_PSE_MASK) && pse) {
>> -            /* 4 MB page */
>> -            start_paddr = (pde & ~0x3fffff) | ((pde & 0x1fe000) << 19);
>> +            /*
>> +             * 4 MB page:
>> +             * bits 39:32 are bits 20:13 of the PDE
>> +             * bit3 31:22 are bits 31:22 of the PDE
>> +             */
>> +            high_paddr = ((hwaddr)(pde & 0x1fe000) << 19);
>> +            start_paddr = (pde & ~0x3fffff) | high_paddr;
>>              if (cpu_physical_memory_is_io(start_paddr)) {
>>                  /* I/O region */
>>                  continue;
> 
> Extra points for extending the comment.

...and a "target-i386: " prefix in the subject would be appreciated,
since it does not seem to fix a general issue.

Andreas

> 
> Reviewed-by: Markus Armbruster <armbru@redhat.com>
> 


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