linux-kernel - [PATCH 04/34] x86/amd-iommu: Add per IOMMU reference counting

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Date:	Fri, 27 Nov 2009 14:55:15 +0100
From:	Joerg Roedel <joerg.roedel@....com>
To:	Ingo Molnar <mingo@...e.hu>
CC:	iommu@...ts.linux-foundation.org, linux-kernel@...r.kernel.org,
	Joerg Roedel <joerg.roedel@....com>
Subject: [PATCH 04/34] 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@....com>
---
 arch/x86/include/asm/amd_iommu_types.h |    2 ++
 arch/x86/kernel/amd_iommu.c            |   12 +++++++++---
 2 files changed, 11 insertions(+), 3 deletions(-)

diff --git a/arch/x86/include/asm/amd_iommu_types.h b/arch/x86/include/asm/amd_iommu_types.h
index ab3e7bf..e68b148 100644
--- a/arch/x86/include/asm/amd_iommu_types.h
+++ b/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 */
+
 };
 
 /*
diff --git a/arch/x86/kernel/amd_iommu.c b/arch/x86/kernel/amd_iommu.c
index 7fe28be..8c38f00 100644
--- a/arch/x86/kernel/amd_iommu.c
+++ b/arch/x86/kernel/amd_iommu.c
@@ -1175,7 +1175,9 @@ static void __attach_device(struct amd_iommu *iommu,
 	/* update DTE entry */
 	set_dte_entry(devid, domain);
 
-	domain->dev_cnt += 1;
+	/* Do reference counting */
+	domain->dev_iommu[iommu->index] += 1;
+	domain->dev_cnt                 += 1;
 
 	/* ready */
 	spin_unlock(&domain->lock);
@@ -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);
@@ -1223,8 +1228,9 @@ static void __detach_device(struct protection_domain *domain, u16 devid)
 
 	amd_iommu_apply_erratum_63(devid);
 
-	/* decrease reference counter */
-	domain->dev_cnt -= 1;
+	/* decrease reference counters */
+	domain->dev_iommu[iommu->index] -= 1;
+	domain->dev_cnt                 -= 1;
 
 	/* ready */
 	spin_unlock(&domain->lock);
-- 
1.6.5.3


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