linux-kernel - [RFC PATCH 1/7] iommu/amd: Refactor amd_iommu_domain_enable

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Message-Id: <20210312090411.6030-2-suravee.suthikulpanit@amd.com>
Date:   Fri, 12 Mar 2021 03:04:05 -0600
From:   Suravee Suthikulpanit <suravee.suthikulpanit@....com>
To:     linux-kernel@...r.kernel.org, iommu@...ts.linux-foundation.org
Cc:     joro@...tes.org, Jon.Grimm@....com, Wei.Huang2@....com,
        Suravee Suthikulpanit <suravee.suthikulpanit@....com>
Subject: [RFC PATCH 1/7] iommu/amd: Refactor amd_iommu_domain_enable_v2

The current function to enable IOMMU v2 also lock the domain.
In order to reuse the same code in different code path, in which
the domain has already been locked, refactor the function to separate
the locking from the enabling logic.

Signed-off-by: Suravee Suthikulpanit <suravee.suthikulpanit@....com>
---
 drivers/iommu/amd/iommu.c | 42 +++++++++++++++++++++++++--------------
 1 file changed, 27 insertions(+), 15 deletions(-)

diff --git a/drivers/iommu/amd/iommu.c b/drivers/iommu/amd/iommu.c
index a69a8b573e40..6f3e42495709 100644
--- a/drivers/iommu/amd/iommu.c
+++ b/drivers/iommu/amd/iommu.c
@@ -88,6 +88,7 @@ struct iommu_cmd {
 struct kmem_cache *amd_iommu_irq_cache;
 
 static void detach_device(struct device *dev);
+static int domain_enable_v2(struct protection_domain *domain, int pasids, bool has_ppr);
 
 /****************************************************************************
  *
@@ -2304,10 +2305,9 @@ void amd_iommu_domain_direct_map(struct iommu_domain *dom)
 }
 EXPORT_SYMBOL(amd_iommu_domain_direct_map);
 
-int amd_iommu_domain_enable_v2(struct iommu_domain *dom, int pasids)
+/* Note: This function expects iommu_domain->lock to be held prior calling the function. */
+static int domain_enable_v2(struct protection_domain *domain, int pasids, bool has_ppr)
 {
-	struct protection_domain *domain = to_pdomain(dom);
-	unsigned long flags;
 	int levels, ret;
 
 	if (pasids <= 0 || pasids > (PASID_MASK + 1))
@@ -2320,17 +2320,6 @@ int amd_iommu_domain_enable_v2(struct iommu_domain *dom, int pasids)
 	if (levels > amd_iommu_max_glx_val)
 		return -EINVAL;
 
-	spin_lock_irqsave(&domain->lock, flags);
-
-	/*
-	 * Save us all sanity checks whether devices already in the
-	 * domain support IOMMUv2. Just force that the domain has no
-	 * devices attached when it is switched into IOMMUv2 mode.
-	 */
-	ret = -EBUSY;
-	if (domain->dev_cnt > 0 || domain->flags & PD_IOMMUV2_MASK)
-		goto out;
-
 	ret = -ENOMEM;
 	domain->gcr3_tbl = (void *)get_zeroed_page(GFP_ATOMIC);
 	if (domain->gcr3_tbl == NULL)
@@ -2344,8 +2333,31 @@ int amd_iommu_domain_enable_v2(struct iommu_domain *dom, int pasids)
 	ret = 0;
 
 out:
-	spin_unlock_irqrestore(&domain->lock, flags);
+	return ret;
+}
 
+int amd_iommu_domain_enable_v2(struct iommu_domain *dom, int pasids)
+{
+	int ret;
+	unsigned long flags;
+	struct protection_domain *pdom = to_pdomain(dom);
+
+	spin_lock_irqsave(&pdom->lock, flags);
+
+	/*
+	 * Save us all sanity checks whether devices already in the
+	 * domain support IOMMUv2. Just force that the domain has no
+	 * devices attached when it is switched into IOMMUv2 mode.
+	 */
+	ret = -EBUSY;
+	if (pdom->dev_cnt > 0 || pdom->flags & PD_IOMMUV2_MASK)
+		goto out;
+
+	if (pdom->dev_cnt == 0 && !(pdom->gcr3_tbl))
+		ret = domain_enable_v2(pdom, pasids, true);
+
+out:
+	spin_unlock_irqrestore(&pdom->lock, flags);
 	return ret;
 }
 EXPORT_SYMBOL(amd_iommu_domain_enable_v2);
-- 
2.17.1