Re: [Qemu-devel] [PATCH 09/29] target-sparc: hypervisor mode takes over nucleus mode

[Artyom Tarasenko]

On Wed, Oct 12, 2016 at 3:29 PM, Richard Henderson <address@hidden> wrote:
> On 10/12/2016 06:33 AM, Artyom Tarasenko wrote:
>>
>> On Mon, Oct 10, 2016 at 11:41 PM, Richard Henderson <address@hidden>
>> wrote:
>>>
>>> On 10/01/2016 05:05 AM, Artyom Tarasenko wrote:
>>>>
>>>>
>>>> Signed-off-by: Artyom Tarasenko <address@hidden>
>>>> ---
>>>>  target-sparc/cpu.h | 6 +++---
>>>>  1 file changed, 3 insertions(+), 3 deletions(-)
>>>>
>>>> diff --git a/target-sparc/cpu.h b/target-sparc/cpu.h
>>>> index 0b5c79f..fbeb8d7 100644
>>>> --- a/target-sparc/cpu.h
>>>> +++ b/target-sparc/cpu.h
>>>> @@ -699,10 +699,10 @@ static inline int cpu_mmu_index(CPUSPARCState
>>>> *env1,
>>>> bool ifetch)
>>>>  #elif !defined(TARGET_SPARC64)
>>>>      return env1->psrs;
>>>>  #else
>>>> -    if (env1->tl > 0) {
>>>> -        return MMU_NUCLEUS_IDX;
>>>> -    } else if (cpu_hypervisor_mode(env1)) {
>>>> +    if (cpu_hypervisor_mode(env1)) {
>>>>          return MMU_HYPV_IDX;
>>>> +    } else if (env1->tl > 0) {
>>>> +        return MMU_NUCLEUS_IDX;
>>>>      } else if (cpu_supervisor_mode(env1)) {
>>>>          return MMU_KERNEL_IDX;
>>>>      } else {
>>>>
>>>
>>> While playing with your patch set, I discovered that we also need a patch
>>> to
>>> get_asi for ASI_N et al to retain MMU_HYPV_IDX, and not decrease
>>> privilege.
>>> This happens *very* early in the prom boot, with the first casx (when
>>> casx
>>> is implemented inline).
>>
>>
>> Why is the bug not visible with the current master? I wonder if we
>> have a symmetrical bug somewhere.
>
>
> Hmm, I dunno.  I assume it has something to do with casx being implemented
> out of line, and using helper_ld_asi instead of tcg_gen_qemu_ld_tl directly.
>

Actually I don't see where the  privilege is decreased: get_asi uses a
local mem_idx variable, the dc->mem_idx is retained.
What patch do you have in mind?


-- 
Regards,
Artyom Tarasenko

SPARC and PPC PReP under qemu blog: http://tyom.blogspot.com/search/label/qemu