[xen staging] xen/x86: account number of foreign mappings in the p2m

[patchbot@xxxxxxx]

commit 8ef1e96a04fb177c89791749234d873ac883a92a
Author:     Roger Pau Monné <roger.pau@xxxxxxxxxx>
AuthorDate: Wed May 29 16:07:55 2024 +0200
Commit:     Jan Beulich <jbeulich@xxxxxxxx>
CommitDate: Wed May 29 16:07:55 2024 +0200

    xen/x86: account number of foreign mappings in the p2m
    
    Such information will be needed in order to remove foreign mappings during
    teardown for HVM guests.
    
    Right now the introduced counter is not consumed.
    
    Signed-off-by: Roger Pau Monné <roger.pau@xxxxxxxxxx>
    Reviewed-by: Jan Beulich <jbeulich@xxxxxxxx>
    Release-acked-by: Oleksii Kurochko <oleksii.kurochko@xxxxxxxxx>
---
 xen/arch/x86/include/asm/p2m.h | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/xen/arch/x86/include/asm/p2m.h b/xen/arch/x86/include/asm/p2m.h
index 111badf89a..107b9f2608 100644
--- a/xen/arch/x86/include/asm/p2m.h
+++ b/xen/arch/x86/include/asm/p2m.h
@@ -380,6 +380,9 @@ struct p2m_domain {
         unsigned int flags;
         unsigned long entry_count;
     } ioreq;
+
+    /* Number of foreign mappings. */
+    unsigned long      nr_foreign;
 #endif /* CONFIG_HVM */
 };
 
@@ -1049,6 +1052,8 @@ static inline int p2m_entry_modify(struct p2m_domain 
*p2m, p2m_type_t nt,
         if ( !page_get_owner_and_reference(mfn_to_page(nfn)) )
             return -EBUSY;
 
+        p2m->nr_foreign++;
+
         break;
 
     default:
@@ -1069,6 +1074,7 @@ static inline int p2m_entry_modify(struct p2m_domain 
*p2m, p2m_type_t nt,
             return -EINVAL;
         }
         put_page(mfn_to_page(ofn));
+        p2m->nr_foreign--;
         break;
 
     default:
--
generated by git-patchbot for /home/xen/git/xen.git#staging