Re: [Xen-devel] [PATCH 01/10] VMX: Enable EPT A/D bit support

[Tim Deegan <tim@xxxxxxx>]

At 10:35 +0800 on 27 Mar (1427452545), Kai Huang wrote:
> @@ -233,6 +233,9 @@ static int ept_split_super_page(struct p2m_domain *p2m, 
> ept_entry_t *ept_entry,
>      if ( !ept_set_middle_entry(p2m, &new_ept) )
>          return 0;
>  
> +    /* It's better to copy A bit of Middle entry from original entry */
> +    new_ept.a = ept_entry->a;

Shouldn't this A bit always be set to 1?  After all we're not using it
for anything, and it doesn't mean the same thing as the A bit in the
superpage entry did.

In fact, thinking about that, we should probably be setting _all_ the
A bits to 1, even in leaf entries, to avoid the overhead of the MMU
having to write them later.

Cheers,

Tim.

_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxx
http://lists.xen.org/xen-devel