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

[Luiz Capitulino <lcapitulino@redhat.com>]

On Mon, 07 Jan 2013 14:10:46 +0100
Andreas Färber <afaerber@suse.de> wrote:

> 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.

I can do that myself when I apply the patch (which will take a little bit,
as I'm just back from vacation).

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