On 11/07/2014 03:40 PM, David Vrabel wrote:
On 07/11/14 14:11, Juergen Gross wrote:
On 11/07/2014 02:54 PM, David Vrabel wrote:
On 06/11/14 05:47, Juergen Gross wrote:
[...]
@@ -526,23 +411,83 @@ unsigned long get_phys_to_machine(unsigned long
pfn)
return IDENTITY_FRAME(pfn);
}
- topidx = p2m_top_index(pfn);
- mididx = p2m_mid_index(pfn);
- idx = p2m_index(pfn);
+ ptep = lookup_address((unsigned long)(xen_p2m_addr + pfn), &level);
+ BUG_ON(!ptep || level != PG_LEVEL_4K);
/*
* The INVALID_P2M_ENTRY is filled in both p2m_*identity
* and in p2m_*missing, so returning the INVALID_P2M_ENTRY
* would be wrong.
*/
- if (p2m_top[topidx][mididx] == p2m_identity)
+ if (pte_pfn(*ptep) == PFN_DOWN(__pa(p2m_identity)))
return IDENTITY_FRAME(pfn);
- return p2m_top[topidx][mididx][idx];
+ return xen_p2m_addr[pfn];
You should test xen_p2m_addr[pfn] == INVALID_P2M_ENTRY before checking
if it's an identity entry. This should skip the more expensive
lookup_address() in the common case.
I do. The check is in __pfn_to_mfn(). get_phys_to_machine() is called in
this case only.
So you do. I missed that.
bool __set_phys_to_machine(unsigned long pfn, unsigned long mfn)
I think you should map p2m_missing and p2m_identity as read-only and do
the new page allocation on a write fault.
set_phys_to_machine() is used every grant map and unmap and in the
common case (already allocated array page) it must be a fast and simple:
xen_p2m_addr[pfn] = mfn;
Nice idea. I'll try it.
You probably want to try this with a custom exception fixup (or abuse
put_user()).
Yeah, that was my idea, too.
Juergen
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majord...@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
