x86/amd-iommu: Add per IOMMU reference counting

This patch adds reference counting for protection domains
per IOMMU. This allows a smarter TLB flushing strategy.
Signed-off-by: Joerg Roedel <joerg.roedel@amd.com>

arch/x86/include/asm/amd_iommu_types.h

@@ -238,7 +238,9 @@ struct protection_domain {
 	unsigned long flags;	/* flags to find out type of domain */
 	bool updated;		/* complete domain flush required */
 	unsigned dev_cnt;	/* devices assigned to this domain */
+	unsigned dev_iommu[MAX_IOMMUS]; /* per-IOMMU reference count */
 	void *priv;		/* private data */
+
 };
 
 /*

arch/x86/kernel/amd_iommu.c

@@ -1175,6 +1175,8 @@ static void __attach_device(struct amd_iommu *iommu,
 	/* update DTE entry */
 	set_dte_entry(devid, domain);
 
+	/* Do reference counting */
+	domain->dev_iommu[iommu->index] += 1;
 	domain->dev_cnt                 += 1;
 
 	/* ready */
@@ -1209,6 +1211,9 @@ static void attach_device(struct amd_iommu *iommu,
  */
 static void __detach_device(struct protection_domain *domain, u16 devid)
 {
+	struct amd_iommu *iommu = amd_iommu_rlookup_table[devid];
+
+	BUG_ON(!iommu);
 
 	/* lock domain */
 	spin_lock(&domain->lock);
@@ -1223,7 +1228,8 @@ static void __detach_device(struct protection_domain *domain, u16 devid)
 
 	amd_iommu_apply_erratum_63(devid);
 
-	/* decrease reference counter */
+	/* decrease reference counters */
+	domain->dev_iommu[iommu->index] -= 1;
 	domain->dev_cnt                 -= 1;
 
 	/* ready */