[PATCH v2 2/2] iommu/vt-d: use marco for dmar_domain's second level size and shift

[Wei Yang]

In the origin commit, the size of the second level is hard coded to an
integer, 256.

This patch defines two marco for the second level size and shift.

Signed-off-by: Wei Yang <richard.weiyang@xxxxxxxxx>
---
 drivers/iommu/intel-iommu.c | 12 ++++++------
 include/linux/intel-iommu.h |  2 ++
 2 files changed, 8 insertions(+), 6 deletions(-)

diff --git a/drivers/iommu/intel-iommu.c b/drivers/iommu/intel-iommu.c
index 1c8b587..dd050d7 100644
--- a/drivers/iommu/intel-iommu.c
+++ b/drivers/iommu/intel-iommu.c
@@ -616,7 +616,7 @@ static struct kmem_cache *iommu_devinfo_cache;
 static struct dmar_domain* get_iommu_domain(struct intel_iommu *iommu, u16 did)
 {
 	struct dmar_domain **domains;
-	int idx = did >> 8;
+	int idx = did >> DMAR_DOMS_SHIFT;
 
 	domains = iommu->domains[idx];
 	if (!domains)
@@ -629,10 +629,10 @@ static void set_iommu_domain(struct intel_iommu *iommu, u16 did,
 			     struct dmar_domain *domain)
 {
 	struct dmar_domain **domains;
-	int idx = did >> 8;
+	int idx = did >> DMAR_DOMS_SHIFT;
 
 	if (!iommu->domains[idx]) {
-		size_t size = 256 * sizeof(struct dmar_domain *);
+		size_t size = DMAR_DOMS_SIZE * sizeof(struct dmar_domain *);
 		iommu->domains[idx] = kzalloc(size, GFP_ATOMIC);
 	}
 
@@ -1634,11 +1634,11 @@ static int iommu_init_domains(struct intel_iommu *iommu)
 		return -ENOMEM;
 	}
 
-	size = DIV_ROUND_UP(ndomains, 256) * sizeof(struct dmar_domain **);
+	size = DIV_ROUND_UP(ndomains, DMAR_DOMS_SIZE) * sizeof(struct dmar_domain **);
 	iommu->domains = kzalloc(size, GFP_KERNEL);
 
 	if (iommu->domains) {
-		size = 256 * sizeof(struct dmar_domain *);
+		size = DMAR_DOMS_SIZE * sizeof(struct dmar_domain *);
 		iommu->domains[0] = kzalloc(size, GFP_KERNEL);
 	}
 
@@ -1699,7 +1699,7 @@ static void disable_dmar_iommu(struct intel_iommu *iommu)
 static void free_dmar_iommu(struct intel_iommu *iommu)
 {
 	if ((iommu->domains) && (iommu->domain_ids)) {
-		int elems = DIV_ROUND_UP(cap_ndoms(iommu->cap), 256);
+		int elems = DIV_ROUND_UP(cap_ndoms(iommu->cap), DMAR_DOMS_SIZE);
 		int i;
 
 		for (i = 0; i < elems; i++)
diff --git a/include/linux/intel-iommu.h b/include/linux/intel-iommu.h
index 2d9b650..afcb7bf 100644
--- a/include/linux/intel-iommu.h
+++ b/include/linux/intel-iommu.h
@@ -412,6 +412,8 @@ struct intel_iommu {
 
 #ifdef CONFIG_INTEL_IOMMU
 	unsigned long 	*domain_ids; /* bitmap of domains */
+#define DMAR_DOMS_SHIFT 8
+#define DMAR_DOMS_SIZE (1 << DMAR_DOMS_SHIFT )
 	struct dmar_domain ***domains; /* ptr to domains */
 	spinlock_t	lock; /* protect context, domain ids */
 	struct root_entry *root_entry; /* virtual address */
-- 
2.5.0