From 9f3c080e41befe73e822b66536e93fb6cba28eef Mon Sep 17 00:00:00 2001
From: Max Wash <mbswash@gmail.com>
Date: Sun, 7 May 2023 21:38:08 +0100
Subject: [PATCH] vm: minimum and maximum zone IDs are now defined in
 arch/../vm.h

---
 arch/x86_64/include/socks/machine/vm.h | 3 +++
 include/socks/vm.h                     | 6 +++---
 vm/cache.c                             | 4 ++++
 vm/page.c                              | 4 ++--
 4 files changed, 12 insertions(+), 5 deletions(-)

diff --git a/arch/x86_64/include/socks/machine/vm.h b/arch/x86_64/include/socks/machine/vm.h
index 11b3418..f52734e 100644
--- a/arch/x86_64/include/socks/machine/vm.h
+++ b/arch/x86_64/include/socks/machine/vm.h
@@ -18,4 +18,7 @@
 #define VM_PAGE_MIN_ORDER VM_PAGE_4K
 #define VM_PAGE_MAX_ORDER VM_PAGE_8M
 
+#define VM_ZONE_MIN VM_ZONE_DMA
+#define VM_ZONE_MAX VM_ZONE_NORMAL
+
 #endif
diff --git a/include/socks/vm.h b/include/socks/vm.h
index 74c8461..53aaeda 100644
--- a/include/socks/vm.h
+++ b/include/socks/vm.h
@@ -56,12 +56,12 @@ enum vm_flags {
 
 enum vm_zone_id {
 	/* NOTE that these are used as indices into the node_zones array in vm/zone.c
-	   they need to be continuous, and must start at 0! */
+	   they need to be continuous, and must start at 0!
+
+	   not all of these zones are implemented for every architecture. */
 	VM_ZONE_DMA     = 0u,
 	VM_ZONE_NORMAL  = 1u,
 	VM_ZONE_HIGHMEM = 2u,
-	VM_ZONE_MIN     = VM_ZONE_DMA,
-	VM_ZONE_MAX     = VM_ZONE_HIGHMEM,
 };
 
 enum vm_page_order {
diff --git a/vm/cache.c b/vm/cache.c
index 7012c9d..6c2ea85 100644
--- a/vm/cache.c
+++ b/vm/cache.c
@@ -82,6 +82,10 @@ void vm_cache_destroy(struct vm_cache *cache)
 static struct vm_slab *alloc_slab(struct vm_cache *cache, enum vm_flags flags)
 {
 	struct vm_page *slab_page = vm_page_alloc(cache->c_page_order, flags);
+	if (!slab_page) {
+		return NULL;
+	}
+
 	struct vm_slab *slab_hdr = NULL;
 	void *slab_data = vm_page_get_vaddr(slab_page);
 
diff --git a/vm/page.c b/vm/page.c
index fd33542..831c1bd 100644
--- a/vm/page.c
+++ b/vm/page.c
@@ -155,7 +155,7 @@ struct vm_page *vm_page_alloc(enum vm_page_order order, enum vm_flags flags)
 {
 	/* TODO prefer nodes closer to us */
 	struct vm_pg_data *node = vm_pg_data_get(0);
-	enum vm_zone_id zone_id = VM_ZONE_HIGHMEM;
+	enum vm_zone_id zone_id = VM_ZONE_MAX;
 	if (flags & VM_GET_DMA) {
 		zone_id = VM_ZONE_DMA;
 	}
@@ -168,7 +168,7 @@ struct vm_page *vm_page_alloc(enum vm_page_order order, enum vm_flags flags)
 			return pg;
 		}
 
-		if (zone_id == VM_ZONE_MIN) {
+		if (zone_id <= VM_ZONE_MIN) {
 			break;
 		}