[PATCH v3 2/3] KVM: s390: Enable adapter_indicators_set to use mapped pages

[Douglas Freimuth <freimuth@linux.ibm.com>]

The S390 adapter_indicators_set function needs to be able to use mapped 
pages so that worked can be processed,on a fast path when interrupts are
disabled. If adapter indicator pages are not mapped then local mapping is 
done on a slow path as it is prior to this patch. For example, Secure
Execution environments will take the local mapping path as it does prior to
this patch.

Signed-off-by: Douglas Freimuth <freimuth@linux.ibm.com>
---
 arch/s390/kvm/interrupt.c | 91 ++++++++++++++++++++++++++++-----------
 1 file changed, 66 insertions(+), 25 deletions(-)

diff --git a/arch/s390/kvm/interrupt.c b/arch/s390/kvm/interrupt.c
index 47bd6361c849..f3183c9ec7f1 100644
--- a/arch/s390/kvm/interrupt.c
+++ b/arch/s390/kvm/interrupt.c
@@ -2847,41 +2847,82 @@ static unsigned long get_ind_bit(__u64 addr, unsigned long bit_nr, bool swap)
 	return swap ? (bit ^ (BITS_PER_LONG - 1)) : bit;
 }
 
+static struct s390_map_info *get_map_info(struct s390_io_adapter *adapter,
+					  u64 addr)
+{
+	struct s390_map_info *map;
+
+	if (!adapter)
+		return NULL;
+
+	list_for_each_entry(map, &adapter->maps, list) {
+		if (map->guest_addr == addr)
+			return map;
+	}
+	return NULL;
+}
+
 static int adapter_indicators_set(struct kvm *kvm,
 				  struct s390_io_adapter *adapter,
 				  struct kvm_s390_adapter_int *adapter_int)
 {
 	unsigned long bit;
 	int summary_set, idx;
-	struct page *ind_page, *summary_page;
+	struct s390_map_info *ind_info, *summary_info;
 	void *map;
+	struct page *ind_page, *summary_page;
+	unsigned long flags;
 
-	ind_page = get_map_page(kvm, adapter_int->ind_addr);
-	if (!ind_page)
-		return -1;
-	summary_page = get_map_page(kvm, adapter_int->summary_addr);
-	if (!summary_page) {
-		put_page(ind_page);
-		return -1;
+	spin_lock_irqsave(&adapter->maps_lock, flags);
+	ind_info = get_map_info(adapter, adapter_int->ind_addr);
+	if (!ind_info) {
+		spin_unlock_irqrestore(&adapter->maps_lock, flags);
+		ind_page = get_map_page(kvm, adapter_int->ind_addr);
+		if (!ind_page)
+			return -1;
+		idx = srcu_read_lock(&kvm->srcu);
+		map = page_address(ind_page);
+		bit = get_ind_bit(adapter_int->ind_addr,
+				  adapter_int->ind_offset, adapter->swap);
+		set_bit(bit, map);
+		mark_page_dirty(kvm, adapter_int->ind_gaddr >> PAGE_SHIFT);
+		set_page_dirty_lock(ind_page);
+		srcu_read_unlock(&kvm->srcu, idx);
+	} else {
+		map = page_address(ind_info->page);
+		bit = get_ind_bit(ind_info->addr, adapter_int->ind_offset, adapter->swap);
+		set_bit(bit, map);
+		spin_unlock_irqrestore(&adapter->maps_lock, flags);
+	}
+	spin_lock_irqsave(&adapter->maps_lock, flags);
+	summary_info = get_map_info(adapter, adapter_int->summary_addr);
+	if (!summary_info) {
+		spin_unlock_irqrestore(&adapter->maps_lock, flags);
+		summary_page = get_map_page(kvm, adapter_int->summary_addr);
+		if (!summary_page && !ind_info) {
+			put_page(ind_page);
+			return -1;
+		}
+		idx = srcu_read_lock(&kvm->srcu);
+		map = page_address(summary_page);
+		bit = get_ind_bit(adapter_int->summary_addr,
+				  adapter_int->summary_offset, adapter->swap);
+		summary_set = test_and_set_bit(bit, map);
+		mark_page_dirty(kvm, adapter_int->summary_gaddr >> PAGE_SHIFT);
+		set_page_dirty_lock(summary_page);
+		srcu_read_unlock(&kvm->srcu, idx);
+	} else {
+		map = page_address(summary_info->page);
+		bit = get_ind_bit(summary_info->addr, adapter_int->summary_offset,
+				  adapter->swap);
+		summary_set = test_and_set_bit(bit, map);
+		spin_unlock_irqrestore(&adapter->maps_lock, flags);
 	}
 
-	idx = srcu_read_lock(&kvm->srcu);
-	map = page_address(ind_page);
-	bit = get_ind_bit(adapter_int->ind_addr,
-			  adapter_int->ind_offset, adapter->swap);
-	set_bit(bit, map);
-	mark_page_dirty(kvm, adapter_int->ind_gaddr >> PAGE_SHIFT);
-	set_page_dirty_lock(ind_page);
-	map = page_address(summary_page);
-	bit = get_ind_bit(adapter_int->summary_addr,
-			  adapter_int->summary_offset, adapter->swap);
-	summary_set = test_and_set_bit(bit, map);
-	mark_page_dirty(kvm, adapter_int->summary_gaddr >> PAGE_SHIFT);
-	set_page_dirty_lock(summary_page);
-	srcu_read_unlock(&kvm->srcu, idx);
-
-	put_page(ind_page);
-	put_page(summary_page);
+	if (!ind_info)
+		put_page(ind_page);
+	if (!summary_info)
+		put_page(summary_page);
 	return summary_set ? 0 : 1;
 }
 
-- 
2.52.0