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

[Markus Armbruster]

Wen Congyang <address@hidden> 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 <address@hidden>
>
> ---
>  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.

Reviewed-by: Markus Armbruster <address@hidden>