linux-kernel - [PATCH v1 4/6] iommu/vt-d: Add VTD_FLAG_IOMMU

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Date:   Sat, 25 Jun 2022 20:52:02 +0800
From:   Lu Baolu <baolu.lu@...ux.intel.com>
To:     Joerg Roedel <joro@...tes.org>, Steve Wahl <steve.wahl@....com>,
        Kevin Tian <kevin.tian@...el.com>
Cc:     David Woodhouse <dwmw2@...radead.org>,
        Jerry Snitselaar <jsnitsel@...hat.com>,
        Mike Travis <mike.travis@....com>,
        Dimitri Sivanich <sivanich@....com>,
        Russ Anderson <russ.anderson@....com>, iommu@...ts.linux.dev,
        iommu@...ts.linux-foundation.org, linux-kernel@...r.kernel.org,
        Lu Baolu <baolu.lu@...ux.intel.com>
Subject: [PATCH v1 4/6] iommu/vt-d: Add VTD_FLAG_IOMMU_PROBED flag

In the IOMMU hot-add path, there's a need to check whether an IOMMU
has been probed. Instead of checking the IOMMU pointer in the global
list, it's better to allocate a flag bit in iommu->flags for this
purpose.

Signed-off-by: Lu Baolu <baolu.lu@...ux.intel.com>
---
 drivers/iommu/intel/iommu.h | 1 +
 drivers/iommu/intel/iommu.c | 5 ++++-
 2 files changed, 5 insertions(+), 1 deletion(-)

diff --git a/drivers/iommu/intel/iommu.h b/drivers/iommu/intel/iommu.h
index 56c3d1a9e155..105a1e7c60d9 100644
--- a/drivers/iommu/intel/iommu.h
+++ b/drivers/iommu/intel/iommu.h
@@ -479,6 +479,7 @@ enum {
 #define VTD_FLAG_TRANS_PRE_ENABLED	(1 << 0)
 #define VTD_FLAG_IRQ_REMAP_PRE_ENABLED	(1 << 1)
 #define VTD_FLAG_SVM_CAPABLE		(1 << 2)
+#define VTD_FLAG_IOMMU_PROBED		(1 << 3)
 
 extern int intel_iommu_sm;
 
diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c
index 78b26fef685e..f6d7055cffd7 100644
--- a/drivers/iommu/intel/iommu.c
+++ b/drivers/iommu/intel/iommu.c
@@ -1695,6 +1695,7 @@ static void free_dmar_iommu(struct intel_iommu *iommu)
 	}
 
 	g_iommus[iommu->seq_id] = NULL;
+	iommu->flags &= ~VTD_FLAG_IOMMU_PROBED;
 
 	/* free context mapping */
 	free_context_table(iommu);
@@ -2951,6 +2952,7 @@ static int __init init_dmars(void)
 		}
 
 		g_iommus[iommu->seq_id] = iommu;
+		iommu->flags |= VTD_FLAG_IOMMU_PROBED;
 
 		intel_iommu_init_qi(iommu);
 
@@ -3460,7 +3462,7 @@ static int intel_iommu_add(struct dmar_drhd_unit *dmaru)
 	int sp, ret;
 	struct intel_iommu *iommu = dmaru->iommu;
 
-	if (g_iommus[iommu->seq_id])
+	if (iommu->flags & VTD_FLAG_IOMMU_PROBED)
 		return 0;
 
 	ret = intel_cap_audit(CAP_AUDIT_HOTPLUG_DMAR, iommu);
@@ -3487,6 +3489,7 @@ static int intel_iommu_add(struct dmar_drhd_unit *dmaru)
 		iommu_disable_translation(iommu);
 
 	g_iommus[iommu->seq_id] = iommu;
+	iommu->flags |= VTD_FLAG_IOMMU_PROBED;
 	ret = iommu_init_domains(iommu);
 	if (ret == 0)
 		ret = iommu_alloc_root_entry(iommu);
-- 
2.25.1