KVM: s390: vsie: stop using "struct page" for vsie page

Now that we no longer use page->index and the page refcount explicitly,
let's avoid messing with "struct page" completely.

Signed-off-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
Reviewed-by: Christoph Schlameuss <schlameuss@linux.ibm.com>
Tested-by: Christoph Schlameuss <schlameuss@linux.ibm.com>
Message-ID: <20250107154344.1003072-5-david@redhat.com>
Signed-off-by: Claudio Imbrenda <imbrenda@linux.ibm.com>

Author: davidhildenbrand

arch/s390/include/asm/kvm_host.h

@@ -931,12 +931,14 @@ struct sie_page2 {
 	u8 reserved928[0x1000 - 0x928];			/* 0x0928 */
 };
 
+struct vsie_page;
+
 struct kvm_s390_vsie {
 	struct mutex mutex;
 	struct radix_tree_root addr_to_page;
 	int page_count;
 	int next;
-	struct page *pages[KVM_MAX_VCPUS];
+	struct vsie_page *pages[KVM_MAX_VCPUS];
 };
 
 struct kvm_s390_gisa_iam {

arch/s390/kvm/vsie.c

@@ -599,7 +599,6 @@ void kvm_s390_vsie_gmap_notifier(struct gmap *gmap, unsigned long start,
 	struct kvm *kvm = gmap->private;
 	struct vsie_page *cur;
 	unsigned long prefix;
-	struct page *page;
 	int i;
 
 	if (!gmap_is_shadow(gmap))
@@ -609,10 +608,9 @@ void kvm_s390_vsie_gmap_notifier(struct gmap *gmap, unsigned long start,
 	 * therefore we can safely reference them all the time.
 	 */
 	for (i = 0; i < kvm->arch.vsie.page_count; i++) {
-		page = READ_ONCE(kvm->arch.vsie.pages[i]);
-		if (!page)
+		cur = READ_ONCE(kvm->arch.vsie.pages[i]);
+		if (!cur)
 			continue;
-		cur = page_to_virt(page);
 		if (READ_ONCE(cur->gmap) != gmap)
 			continue;
 		prefix = cur->scb_s.prefix << GUEST_PREFIX_SHIFT;
@@ -1384,14 +1382,12 @@ static void put_vsie_page(struct vsie_page *vsie_page)
 static struct vsie_page *get_vsie_page(struct kvm *kvm, unsigned long addr)
 {
 	struct vsie_page *vsie_page;
-	struct page *page;
 	int nr_vcpus;
 
 	rcu_read_lock();
-	page = radix_tree_lookup(&kvm->arch.vsie.addr_to_page, addr >> 9);
+	vsie_page = radix_tree_lookup(&kvm->arch.vsie.addr_to_page, addr >> 9);
 	rcu_read_unlock();
-	if (page) {
-		vsie_page = page_to_virt(page);
+	if (vsie_page) {
 		if (try_get_vsie_page(vsie_page)) {
 			if (vsie_page->scb_gpa == addr)
 				return vsie_page;
@@ -1411,20 +1407,18 @@ static struct vsie_page *get_vsie_page(struct kvm *kvm, unsigned long addr)
 
 	mutex_lock(&kvm->arch.vsie.mutex);
 	if (kvm->arch.vsie.page_count < nr_vcpus) {
-		page = alloc_page(GFP_KERNEL_ACCOUNT | __GFP_ZERO | GFP_DMA);
-		if (!page) {
+		vsie_page = (void *)__get_free_page(GFP_KERNEL_ACCOUNT | __GFP_ZERO | GFP_DMA);
+		if (!vsie_page) {
 			mutex_unlock(&kvm->arch.vsie.mutex);
 			return ERR_PTR(-ENOMEM);
 		}
-		vsie_page = page_to_virt(page);
 		__set_bit(VSIE_PAGE_IN_USE, &vsie_page->flags);
-		kvm->arch.vsie.pages[kvm->arch.vsie.page_count] = page;
+		kvm->arch.vsie.pages[kvm->arch.vsie.page_count] = vsie_page;
 		kvm->arch.vsie.page_count++;
 	} else {
 		/* reuse an existing entry that belongs to nobody */
 		while (true) {
-			page = kvm->arch.vsie.pages[kvm->arch.vsie.next];
-			vsie_page = page_to_virt(page);
+			vsie_page = kvm->arch.vsie.pages[kvm->arch.vsie.next];
 			if (try_get_vsie_page(vsie_page))
 				break;
 			kvm->arch.vsie.next++;
@@ -1438,7 +1432,8 @@ static struct vsie_page *get_vsie_page(struct kvm *kvm, unsigned long addr)
 	vsie_page->scb_gpa = ULONG_MAX;
 
 	/* Double use of the same address or allocation failure. */
-	if (radix_tree_insert(&kvm->arch.vsie.addr_to_page, addr >> 9, page)) {
+	if (radix_tree_insert(&kvm->arch.vsie.addr_to_page, addr >> 9,
+			      vsie_page)) {
 		put_vsie_page(vsie_page);
 		mutex_unlock(&kvm->arch.vsie.mutex);
 		return NULL;
@@ -1519,20 +1514,18 @@ void kvm_s390_vsie_init(struct kvm *kvm)
 void kvm_s390_vsie_destroy(struct kvm *kvm)
 {
 	struct vsie_page *vsie_page;
-	struct page *page;
 	int i;
 
 	mutex_lock(&kvm->arch.vsie.mutex);
 	for (i = 0; i < kvm->arch.vsie.page_count; i++) {
-		page = kvm->arch.vsie.pages[i];
+		vsie_page = kvm->arch.vsie.pages[i];
 		kvm->arch.vsie.pages[i] = NULL;
-		vsie_page = page_to_virt(page);
 		release_gmap_shadow(vsie_page);
 		/* free the radix tree entry */
 		if (vsie_page->scb_gpa != ULONG_MAX)
 			radix_tree_delete(&kvm->arch.vsie.addr_to_page,
 					  vsie_page->scb_gpa >> 9);
-		__free_page(page);
+		free_page((unsigned long)vsie_page);
 	}
 	kvm->arch.vsie.page_count = 0;
 	mutex_unlock(&kvm->arch.vsie.mutex);