[PATCH v3 4/7] iova: Add iova_domain_len_is_cached()

[John Garry]

Add a function to check whether an IOVA domain currently caches a given
upper IOVA len exactly.

Signed-off-by: John Garry <john.garry@xxxxxxxxxx>
---
 drivers/iommu/iova.c | 11 +++++++++++
 include/linux/iova.h |  8 +++++++-
 2 files changed, 18 insertions(+), 1 deletion(-)

diff --git a/drivers/iommu/iova.c b/drivers/iommu/iova.c
index 0e4c0e55178a..95892a0433cc 100644
--- a/drivers/iommu/iova.c
+++ b/drivers/iommu/iova.c
@@ -872,6 +872,17 @@ static void iova_magazine_push(struct iova_magazine *mag, unsigned long pfn)
 	mag->pfns[mag->size++] = pfn;
 }
 
+static unsigned long iova_len_to_rcache_max(unsigned long iova_len)
+{
+	return order_base_2(iova_len) + 1;
+}
+
+/* Test if iova_len range cached upper limit matches that of IOVA domain */
+bool iova_domain_len_is_cached(struct iova_domain *iovad, unsigned long iova_len)
+{
+	return iova_len_to_rcache_max(iova_len) == iovad->rcache_max_size;
+}
+
 static void init_iova_rcaches(struct iova_domain *iovad)
 {
 	struct iova_cpu_rcache *cpu_rcache;
diff --git a/include/linux/iova.h b/include/linux/iova.h
index 9974e1d3e2bc..04cc8eb6de38 100644
--- a/include/linux/iova.h
+++ b/include/linux/iova.h
@@ -136,7 +136,8 @@ static inline unsigned long iova_pfn(struct iova_domain *iovad, dma_addr_t iova)
 #if IS_ENABLED(CONFIG_IOMMU_IOVA)
 int iova_cache_get(void);
 void iova_cache_put(void);
-
+bool iova_domain_len_is_cached(struct iova_domain *iovad,
+			       unsigned long iova_len);
 void free_iova(struct iova_domain *iovad, unsigned long pfn);
 void __free_iova(struct iova_domain *iovad, struct iova *iova);
 struct iova *alloc_iova(struct iova_domain *iovad, unsigned long size,
@@ -158,6 +159,11 @@ int init_iova_flush_queue(struct iova_domain *iovad,
 struct iova *find_iova(struct iova_domain *iovad, unsigned long pfn);
 void put_iova_domain(struct iova_domain *iovad);
 #else
+static inline bool iova_domain_len_is_cached(struct iova_domain *iovad,
+					     unsigned long iova_len)
+{
+	return false;
+}
 static inline int iova_cache_get(void)
 {
 	return -ENOTSUPP;
-- 
2.26.2