Re: [Xen-devel] [PATCH 02/11] VMX: implement suppress #VE.

[Tim Deegan <tim@xxxxxxx>]

At 10:46 -0800 on 15 Jan (1421315210), Ed White wrote:
> On 01/15/2015 08:25 AM, Tim Deegan wrote:
> > Hi,
> > 
> > At 13:26 -0800 on 09 Jan (1420806392), Ed White wrote:
> >>  static inline bool_t is_epte_valid(ept_entry_t *e)
> >>  {
> >> -    return (e->epte != 0 && e->sa_p2mt != p2m_invalid);
> >> +    return (e->valid != 0 && e->sa_p2mt != p2m_invalid);
> > 
> > This test for 0 is just catching uninitialised entries in freshly
> > allocated pages.  Rather than changing it to ignore bit 63, this loop...
> > 
> >>  }
> >>  
> >>  /* returns : 0 for success, -errno otherwise */
> >> @@ -194,6 +194,19 @@ static int ept_set_middle_entry(struct p2m_domain 
> >> *p2m, ept_entry_t *ept_entry)
> >>  
> >>      ept_entry->r = ept_entry->w = ept_entry->x = 1;
> >>  
> >> +    /* Disable #VE on all entries */ 
> >> +    if ( cpu_has_vmx_virt_exceptions )
> >> +    {
> >> +        ept_entry_t *table = __map_domain_page(pg);
> >> +
> >> +        for ( int i = 0; i < EPT_PAGETABLE_ENTRIES; i++ )
> >> +            table[i].suppress_ve = 1;
> > 
> > ...should set the type of the empty entries to p2m_invalid as it goes.
> > 
> >> +    /* Disable #VE on all entries */
> >> +    if ( cpu_has_vmx_virt_exceptions )
> >> +    {
> >> +        ept_entry_t *table =
> >> +            map_domain_page(pagetable_get_pfn(p2m_get_pagetable(p2m)));
> >> +
> >> +        for ( int i = 0; i < EPT_PAGETABLE_ENTRIES; i++ )
> >> +            table[i].suppress_ve = 1;
> > 
> > And the same here.
> 
> You mean do that unconditionally, regardless of hardware #VE?

Yes, I think that would be OK, and make for slightly cleaner code.  If
you prefer, you can set the type only for #VE hardware and leave the
'e->epte != 0' test as it is.

Cheers,

Tim.

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