Re: [Xen-devel] [PATCH v4] x86/mm: Add mem access rights to NPT

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 24.07.18 at 11:28, <rcojocaru@xxxxxxxxxxxxxxx> wrote:
> On 07/24/2018 11:55 AM, Jan Beulich wrote:
>>> +    if ( cpu_has_svm && !p2m->mem_access_settings )
>>> +    {
>>> +        p2m->mem_access_settings = xmalloc(struct radix_tree_root);
>>> +
>>> +        if( !p2m->mem_access_settings )
>> Style.
>> 
>>> +        {
>>> +            xfree(d->arch.monitor.msr_bitmap);
>>> +            return -ENOMEM;
>>> +        }
>>> +        radix_tree_init(p2m->mem_access_settings);
>>> +    }
>> What's the SVM connection here? Please don't forget that p2m-pt.c
>> also serves the shadow case. Perhaps struct p2m_domain should
>> contain a boolean indicator whether this auxiliary data structure is
>> needed?
> 
> Would it not work to simply check for "if ( cpu_has_svm &&
> p2m_is_hostp2m(p2m) && !p2m->mem_access_settings )" here?
> 
> In the shadow case, will not p2m->p2m_class be p2m_nested?

Maybe, but that wasn't the point of my remark. I want to
get rid of the cpu_has_svm here, not have it amended.

Jan



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