x86/mm: Clean up mem event structures on domain destruction

Otherwise we wind up with zombie domains, still holding onto refs to the mem
event ring pages.

Signed-off-by: Andres Lagar-Cavilla <andres@lagarcavilla.org>
Acked-by: Tim Deegan <tim@xen.org>
Committed-by: Tim Deegan <tim@xen.org>

xen/arch/x86/mm/mem_event.c

@@ -486,6 +486,17 @@ int do_mem_event_op(int op, uint32_t domain, void *arg)
     return ret;
 }
 
+/* Clean up on domain destruction */
+void mem_event_cleanup(struct domain *d)
+{
+    if ( d->mem_event->paging.ring_page )
+        (void)mem_event_disable(d, &d->mem_event->paging);
+    if ( d->mem_event->access.ring_page )
+        (void)mem_event_disable(d, &d->mem_event->access);
+    if ( d->mem_event->share.ring_page )
+        (void)mem_event_disable(d, &d->mem_event->share);
+}
+
 int mem_event_domctl(struct domain *d, xen_domctl_mem_event_op_t *mec,
                      XEN_GUEST_HANDLE(void) u_domctl)
 {

xen/common/domain.c

@@ -479,6 +479,9 @@ int domain_kill(struct domain *d)
             break;
         }
         d->is_dying = DOMDYING_dead;
+        /* Mem event cleanup has to go here because the rings 
+         * have to be put before we call put_domain. */
+        mem_event_cleanup(d);
         put_domain(d);
         send_global_virq(VIRQ_DOM_EXC);
         /* fallthrough */

xen/include/asm-arm/mm.h

@@ -247,7 +247,8 @@ int  get_page(struct page_info *page, struct domain *domain);
         machine_to_phys_mapping[(mfn)] = (pfn);                \
     })
 
-#define put_gfn(d, g)   ((void)0)
+static inline void put_gfn(struct domain *d, unsigned long gfn) {}
+static inline void mem_event_cleanup(struct domain *d) {}
 
 #define INVALID_MFN             (~0UL)
 

xen/include/asm-ia64/mm.h

@@ -551,7 +551,8 @@ extern u64 translate_domain_pte(u64 pteval, u64 address, u64 itir__,
     gmfn_to_mfn_foreign((_d), (gpfn))
 
 #define get_gfn_untyped(d, gpfn) gmfn_to_mfn(d, gpfn)
-#define put_gfn(d, g)   ((void)0)
+static inline void put_gfn(struct domain *d, unsigned long gfn) {}
+static inline void mem_event_cleanup(struct domain *d) {}
 
 #define __gpfn_invalid(_d, gpfn)			\
 	(lookup_domain_mpa((_d), ((gpfn)<<PAGE_SHIFT), NULL) == INVALID_MFN)

xen/include/asm-x86/mm.h

@@ -634,6 +634,12 @@ unsigned int domain_clamp_alloc_bitsize(struct domain *d, unsigned int bits);
 
 unsigned long domain_get_maximum_gpfn(struct domain *d);
 
+#ifdef CONFIG_X86_64
+void mem_event_cleanup(struct domain *d);
+#else
+static inline void mem_event_cleanup(struct domain *d) {}
+#endif
+
 extern struct domain *dom_xen, *dom_io, *dom_cow;	/* for vmcoreinfo */
 
 /* Definition of an mm lock: spinlock with extra fields for debugging */