Re: [Qemu-devel] [PATCH] target-i386: fix disassembly with PAE=1, PG=0

[Paolo Bonzini <pbonzini@redhat.com>]

Il 30/08/2013 11:58, Paolo Bonzini ha scritto:
> CR4.PAE=1 will not enable paging if CR0.PG=0, but the "if" chain
> in x86_cpu_get_phys_page_debug says otherwise.  Check CR0.PG
> before everything else.
> 
> Fixes "-d in_asm" for a code section at the beginning of OVMF.
> 
> Cc: Richard Henderson <rth@twiddle.net>
> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
> ---
>  target-i386/helper.c | 34 ++++++++++++++++------------------
>  1 file changed, 16 insertions(+), 18 deletions(-)
> 
> diff --git a/target-i386/helper.c b/target-i386/helper.c
> index bf3e2ac..7f74e5d 100644
> --- a/target-i386/helper.c
> +++ b/target-i386/helper.c
> @@ -894,7 +894,10 @@ hwaddr x86_cpu_get_phys_page_debug(CPUState *cs, vaddr addr)
>      uint32_t page_offset;
>      int page_size;
>  
> -    if (env->cr[4] & CR4_PAE_MASK) {
> +    if (!(env->cr[0] & CR0_PG_MASK)) {
> +        pte = addr & env->a20_mask;
> +        page_size = 4096;
> +    } else if (env->cr[4] & CR4_PAE_MASK) {
>          target_ulong pdpe_addr;
>          uint64_t pde, pdpe;
>  
> @@ -952,26 +955,21 @@ hwaddr x86_cpu_get_phys_page_debug(CPUState *cs, vaddr addr)
>      } else {
>          uint32_t pde;
>  
> -        if (!(env->cr[0] & CR0_PG_MASK)) {
> -            pte = addr;
> -            page_size = 4096;
> +        /* page directory entry */
> +        pde_addr = ((env->cr[3] & ~0xfff) + ((addr >> 20) & 0xffc)) & env->a20_mask;
> +        pde = ldl_phys(pde_addr);
> +        if (!(pde & PG_PRESENT_MASK))
> +            return -1;
> +        if ((pde & PG_PSE_MASK) && (env->cr[4] & CR4_PSE_MASK)) {
> +            pte = pde & ~0x003ff000; /* align to 4MB */
> +            page_size = 4096 * 1024;
>          } else {
>              /* page directory entry */
> -            pde_addr = ((env->cr[3] & ~0xfff) + ((addr >> 20) & 0xffc)) & env->a20_mask;
> -            pde = ldl_phys(pde_addr);
> -            if (!(pde & PG_PRESENT_MASK))
> +            pte_addr = ((pde & ~0xfff) + ((addr >> 10) & 0xffc)) & env->a20_mask;
> +            pte = ldl_phys(pte_addr);
> +            if (!(pte & PG_PRESENT_MASK))
>                  return -1;
> -            if ((pde & PG_PSE_MASK) && (env->cr[4] & CR4_PSE_MASK)) {
> -                pte = pde & ~0x003ff000; /* align to 4MB */
> -                page_size = 4096 * 1024;
> -            } else {
> -                /* page directory entry */
> -                pte_addr = ((pde & ~0xfff) + ((addr >> 10) & 0xffc)) & env->a20_mask;
> -                pte = ldl_phys(pte_addr);
> -                if (!(pte & PG_PRESENT_MASK))
> -                    return -1;
> -                page_size = 4096;
> -            }
> +            page_size = 4096;
>          }
>          pte = pte & env->a20_mask;
>      }
> 

Should also go in qemu-stable.

Paolo