[PATCH v10 2/3] KVM: s390: Enable adapter_indicators_set to use mapped pages

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

The s390 adapter_indicators_set function can now be optimized to use
long-term mapped pages when available so that work 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.

Reviewed-by: Matthew Rosato <mjrosato@linux.ibm.com>
Signed-off-by: Douglas Freimuth <freimuth@linux.ibm.com>
---
 arch/s390/kvm/interrupt.c | 87 ++++++++++++++++++++++++++++-----------
 1 file changed, 63 insertions(+), 24 deletions(-)

diff --git a/arch/s390/kvm/interrupt.c b/arch/s390/kvm/interrupt.c
index d066a282271e..b5304816aaa0 100644
--- a/arch/s390/kvm/interrupt.c
+++ b/arch/s390/kvm/interrupt.c
@@ -2892,41 +2892,80 @@ 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->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 = pin_map_page(kvm, adapter_int->ind_addr, 0);
-	if (!ind_page)
-		return -1;
-	summary_page = pin_map_page(kvm, adapter_int->summary_addr, 0);
-	if (!summary_page) {
+	ind_page = NULL;
+
+	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 = pin_map_page(kvm, adapter_int->ind_addr, 0);
+		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);
 		unpin_user_page(ind_page);
-		return -1;
+	} 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 = pin_map_page(kvm, adapter_int->summary_addr, 0);
+		if (WARN_ON_ONCE(!summary_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);
+		unpin_user_page(summary_page);
+	} 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);
-
-	unpin_user_page(ind_page);
-	unpin_user_page(summary_page);
 	return summary_set ? 0 : 1;
 }
 
-- 
2.54.0