1 files changed, 47 insertions, 7 deletions

diff --git a/arch/x86/xen/p2m.c b/arch/x86/xen/p2m.c
index b5949e5a83ec..a3cc33091f46 100644
--- a/arch/x86/xen/p2m.c
+++ b/arch/x86/xen/p2m.c
@@ -416,6 +416,9 @@ void __init xen_vmalloc_p2m_tree(void)
 	xen_p2m_last_pfn = xen_max_p2m_pfn;
 
 	p2m_limit = (phys_addr_t)P2M_LIMIT * 1024 * 1024 * 1024 / PAGE_SIZE;
+	if (!p2m_limit && IS_ENABLED(CONFIG_XEN_UNPOPULATED_ALLOC))
+		p2m_limit = xen_start_info->nr_pages * XEN_EXTRA_MEM_RATIO;
+
 	vm.flags = VM_ALLOC;
 	vm.size = ALIGN(sizeof(unsigned long) * max(xen_max_p2m_pfn, p2m_limit),
 			PMD_SIZE * PMDS_PER_MID_PAGE);
@@ -652,10 +655,9 @@ bool __set_phys_to_machine(unsigned long pfn, unsigned long mfn)
 	pte_t *ptep;
 	unsigned int level;
 
-	if (unlikely(pfn >= xen_p2m_size)) {
-		BUG_ON(mfn != INVALID_P2M_ENTRY);
-		return true;
-	}
+	/* Only invalid entries allowed above the highest p2m covered frame. */
+	if (unlikely(pfn >= xen_p2m_size))
+		return mfn == INVALID_P2M_ENTRY;
 
 	/*
 	 * The interface requires atomic updates on p2m elements.
@@ -710,6 +712,8 @@ int set_foreign_p2m_mapping(struct gnttab_map_grant_ref *map_ops,
 
 	for (i = 0; i < count; i++) {
 		unsigned long mfn, pfn;
+		struct gnttab_unmap_grant_ref unmap[2];
+		int rc;
 
 		/* Do not add to override if the map failed. */
 		if (map_ops[i].status != GNTST_okay ||
@@ -727,10 +731,46 @@ int set_foreign_p2m_mapping(struct gnttab_map_grant_ref *map_ops,
 
 		WARN(pfn_to_mfn(pfn) != INVALID_P2M_ENTRY, "page must be ballooned");
 
-		if (unlikely(!set_phys_to_machine(pfn, FOREIGN_FRAME(mfn)))) {
-			ret = -ENOMEM;
-			goto out;
+		if (likely(set_phys_to_machine(pfn, FOREIGN_FRAME(mfn))))
+			continue;
+
+		/*
+		 * Signal an error for this slot. This in turn requires
+		 * immediate unmapping.
+		 */
+		map_ops[i].status = GNTST_general_error;
+		unmap[0].host_addr = map_ops[i].host_addr,
+		unmap[0].handle = map_ops[i].handle;
+		map_ops[i].handle = ~0;
+		if (map_ops[i].flags & GNTMAP_device_map)
+			unmap[0].dev_bus_addr = map_ops[i].dev_bus_addr;
+		else
+			unmap[0].dev_bus_addr = 0;
+
+		if (kmap_ops) {
+			kmap_ops[i].status = GNTST_general_error;
+			unmap[1].host_addr = kmap_ops[i].host_addr,
+			unmap[1].handle = kmap_ops[i].handle;
+			kmap_ops[i].handle = ~0;
+			if (kmap_ops[i].flags & GNTMAP_device_map)
+				unmap[1].dev_bus_addr = kmap_ops[i].dev_bus_addr;
+			else
+				unmap[1].dev_bus_addr = 0;
 		}
+
+		/*
+		 * Pre-populate both status fields, to be recognizable in
+		 * the log message below.
+		 */
+		unmap[0].status = 1;
+		unmap[1].status = 1;
+
+		rc = HYPERVISOR_grant_table_op(GNTTABOP_unmap_grant_ref,
+					       unmap, 1 + !!kmap_ops);
+		if (rc || unmap[0].status != GNTST_okay ||
+		    unmap[1].status != GNTST_okay)
+			pr_err_once("gnttab unmap failed: rc=%d st0=%d st1=%d\n",
+				    rc, unmap[0].status, unmap[1].status);
 	}
 
 out: