Re: [Qemu-devel] [PATCH v2 4/4] target-i386: Add NPT support

[Jan Kiszka]

On 2018-06-30 08:05, Paolo Bonzini wrote:
> On 30/06/2018 07:25, Jan Kiszka wrote:
>> On 2018-06-27 14:14, Paolo Bonzini wrote:
>>> On 03/04/2018 17:36, Jan Kiszka wrote:
>>>>  
>>>> +static hwaddr get_hphys(CPUState *cs, hwaddr gphys, MMUAccessType 
>>>> access_type,
>>>> +                        int *prot)
>>>> +{
>>>> +    CPUX86State *env = &X86_CPU(cs)->env;
>>>> +    uint64_t rsvd_mask = PG_HI_RSVD_MASK;
>>>> +    uint64_t ptep, pte;
>>>> +    uint64_t exit_info_1 = 0;
>>>> +    target_ulong pde_addr, pte_addr;
>>>> +    uint32_t page_offset;
>>>> +    int page_size;
>>>> +
>>>> +    if (likely(!(env->hflags & HF_NPT_MASK))) {
>>>> +        return gphys;
>>>> +    }
>>>
>>> hflags are a somewhat limited resource.  Can this go in hflags2?
>>>
>>
>> Will have a look - I don't seen why not. Or is there any special
>> semantical difference between both fields?
> 
> Yes, hflags become flags of the translation block, while hflags2 are
> just random processor state.  If translate.c uses it you must use
> hflags, but here hflags2 should be safe.

Indeed. We only change it at vmentry/exit, and that is already a
translation block barrier.

v2 is on the way.

Jan

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