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

[Tim Deegan <tim@xen.org>]

At 10:30 -0700 on 25 Mar (1427279417), Ed White wrote:
> On 01/15/2015 10:46 AM, 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.
> 
> I have some time to work on this patch series again, and although I tried
> this it doesn't eliminate all the instances of epte being zero with the
> possible exception of suppress_ve. I spent some time trying to find all
> cases where that happens without success, so I've used Andrew's suggestion
> of using a mask.

Fair enough.  Thanks for trying it.

Tim.