During a VM fork we copy the shared_info page; however, we also need to ensure
that the page is mapped into the same GFN in the fork as its in the parent.
Signed-off-by: Tamas K Lengyel <tamas.lengyel@intel.com>
Suggested-by: Roger Pau Monne <roger.pau@citrix.com>
---
xen/arch/x86/mm/mem_sharing.c | 25 +++++++++++++++++++++++++
1 file changed, 25 insertions(+)
diff --git a/xen/arch/x86/mm/mem_sharing.c b/xen/arch/x86/mm/mem_sharing.c
index 344a5bfb3d..a1dea8fedb 100644
--- a/xen/arch/x86/mm/mem_sharing.c
+++ b/xen/arch/x86/mm/mem_sharing.c
@@ -1656,6 +1656,7 @@ static void copy_tsc(struct domain *cd, struct domain *d)
static int copy_special_pages(struct domain *cd, struct domain *d)
{
mfn_t new_mfn, old_mfn;
+ gfn_t new_gfn, old_gfn;
struct p2m_domain *p2m = p2m_get_hostp2m(cd);
static const unsigned int params[] =
{
@@ -1701,6 +1702,30 @@ static int copy_special_pages(struct domain *cd, struct domain *d)
new_mfn = _mfn(virt_to_mfn(cd->shared_info));
copy_domain_page(new_mfn, old_mfn);
+ old_gfn = _gfn(get_gpfn_from_mfn(mfn_x(old_mfn)));
+ new_gfn = _gfn(get_gpfn_from_mfn(mfn_x(new_mfn)));
+
+ if ( !gfn_eq(old_gfn, new_gfn) )
+ {
+ if ( !gfn_eq(new_gfn, INVALID_GFN) )
+ {
+ /* if shared_info is mapped to a different gfn just remove it */
+ rc = p2m->set_entry(p2m, new_gfn, INVALID_MFN, PAGE_ORDER_4K,
+ p2m_invalid, p2m->default_access, -1);
+ if ( rc )
+ return rc;
+ }
+
+ if ( !gfn_eq(old_gfn, INVALID_GFN) )
+ {
+ /* now map it to the same gfn as the parent */
+ rc = p2m->set_entry(p2m, old_gfn, new_mfn, PAGE_ORDER_4K,
+ p2m_ram_rw, p2m->default_access, -1);
+ if ( rc )
+ return rc;
+ }
+ }
+
return 0;
}
--
2.20.1