Re: [Xen-devel] [PATCH v5 2/3] x86/altp2m: Add a hvmop for setting the suppress #VE bit

[Razvan Cojocaru <rcojocaru@xxxxxxxxxxxxxxx>]

On 9/20/18 2:34 PM, George Dunlap wrote:
>> +int p2m_set_suppress_ve(struct domain *d, gfn_t gfn, bool suppress_ve,
>> +                        unsigned int altp2m_idx)
> This should clearly be in p2m.c, and...
> 
>> +{
>> +    struct p2m_domain *host_p2m = p2m_get_hostp2m(d);
>> +    struct p2m_domain *ap2m = NULL;
>> +    struct p2m_domain *p2m;
>> +    mfn_t mfn;
>> +    p2m_access_t a;
>> +    p2m_type_t t;
>> +    int rc;
>> +
>> +    if ( !cpu_has_vmx_virt_exceptions )
>> +        return -EOPNOTSUPP;
> We should avoid Intel-specific checks in common code.
> 
> In fact, this is wrong, because you can choose to run a guest in shadow
> mode even on a system with virt exceptions -- in which case you'd
> trigger the ASSERT() in p2m-pt.c:p2m_pt_set_entry().
> 
> Probably what should happen is that we should move the vmx check into
> p2m-ept.c:p2m_ept_set_entry(), and replace the ASSERT(sve = 0) in
> p2m-pt.c:p2m_pt_set_entry() with "if ( sve != 0 ) return -ENOTSUPP;".
> 
> Although what should probably *really* happen is that
> `HVMOP_altp2m_vcpu_enable_notify` should fail with -EOPNOTSUPP instead
> of silently succeeding.

Do you mean HVMOP_altp2m_set_suppress_ve here, or am I misunderstanding
your comment? I'm happy to do the exact modifications you've requested
above but I'm afraid I don't follow the HVMOP_altp2m_vcpu_enable_notify
comment.


Thanks,
Razvan

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