On 2015/6/12 10:43, Chen, Tiejun wrote:
On 2015/6/11 22:07, Tim Deegan wrote:
At 17:31 +0800 on 11 Jun (1434043916), Chen, Tiejun wrote:
while ( base_pfn < end_pfn )
{
- int err = intel_iommu_map_page(d, base_pfn, base_pfn,
-
IOMMUF_readable|IOMMUF_writable);
+ int err = set_identity_p2m_entry(d, base_pfn, p2m_access_rw);
if ( err )
return err;
Tim has another comment to replace earlier unmap with
Yes, I knew this.
guest_physmap_remove_page() which will call iommu
unmap internally. Please include this change too.
But,
guest_physmap_remove_page()
|
+ p2m_remove_page()
|
+ iommu_unmap_page()
|
+ p2m_set_entry(p2m, gfn, _mfn(INVALID_MFN), xxx)
I think this already remove these pages both on ept/vt-d sides, right?
Yes; this is about this code further up in the same function:
while ( base_pfn < end_pfn )
{
if ( intel_iommu_unmap_page(d, base_pfn) )
ret = -ENXIO;
base_pfn++;
}
which ought to be calling guest_physmap_remove_page() or similar, to
make sure that both iommu and EPT mappings get removed.
I still just think current implementation might be fine at this point.
We have two scenarios here, the case of shared ept and the case of
non-shared ept. But no matter what case we're tracking, shouldn't
guest_physmap_remove_page() always call p2m->set_entry() to clear *all*
*valid* mfn which is owned by a given VM? And p2m->set_entry() also
calls iommu_unmap_page() internally. So nothing special should further
consider.
If I'm wrong or misunderstanding, please correct me :)
Sorry for my misunderstanding to this. Right now Kevin help me
understand what you mean. Sounds like we should address something
specific to unmap rmrr here.
So I will do this as follows:
#1. Provide a clear helper
+int clear_identity_p2m_entry(struct domain *d, unsigned long gfn,
+ unsigned int page_order)
+{
+ struct p2m_domain *p2m = p2m_get_hostp2m(d);
+ int ret;
+ gfn_lock(p2m, gfn, page_order);
+ ret = p2m_remove_page(p2m, gfn, gfn, page_order);
+ gfn_unlock(p2m, gfn, page_order);
+ return ret;
+}
+
#2. Call such a helper
@@ -1840,7 +1840,7 @@ static int rmrr_identity_mapping(struct domain *d,
bool_t map,
while ( base_pfn < end_pfn )
{
- if ( intel_iommu_unmap_page(d, base_pfn) )
+ if ( clear_identity_p2m_entry(d, base_pfn, 0) )
ret = -ENXIO;
base_pfn++;
}
Is this right?
Thanks
Tiejun
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