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From:   Keqian Zhu <zhukeqian1@huawei.com>
To:     <linux-kernel@vger.kernel.org>,
        <linux-arm-kernel@lists.infradead.org>,
        <iommu@lists.linux-foundation.org>, <kvm@vger.kernel.org>,
        <kvmarm@lists.cs.columbia.edu>,
        Alex Williamson <alex.williamson@redhat.com>,
        Cornelia Huck <cohuck@redhat.com>,
        Will Deacon <will@kernel.org>, "Marc Zyngier" <maz@kernel.org>,
        Catalin Marinas <catalin.marinas@arm.com>
CC:     Mark Rutland <mark.rutland@arm.com>,
        James Morse <james.morse@arm.com>,
        Robin Murphy <robin.murphy@arm.com>,
        Joerg Roedel <joro@8bytes.org>,
        "Daniel Lezcano" <daniel.lezcano@linaro.org>,
        Thomas Gleixner <tglx@linutronix.de>,
        Suzuki K Poulose <suzuki.poulose@arm.com>,
        Julien Thierry <julien.thierry.kdev@gmail.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        Alexios Zavras <alexios.zavras@intel.com>,
        <wanghaibin.wang@huawei.com>, <jiangkunkun@huawei.com>
Subject: [PATCH 1/6] vfio/iommu_type1: Make an explicit "promote" semantic
Date:   Thu, 7 Jan 2021 12:43:56 +0800
Message-ID: <20210107044401.19828-2-zhukeqian1@huawei.com>
In-Reply-To: <20210107044401.19828-1-zhukeqian1@huawei.com>
References: <20210107044401.19828-1-zhukeqian1@huawei.com>
MIME-Version: 1.0
Content-Type: text/plain
Precedence: bulk

When we want to promote the pinned_page_dirty_scope of vfio_iommu,
we call the "update" function to visit all vfio_group, but when we
want to downgrade this, we can set the flag as false directly.

So we'd better make an explicit "promote" semantic to the "update"
function. BTW, if vfio_iommu already has been promoted, then return
early.

Signed-off-by: Keqian Zhu <zhukeqian1@huawei.com>
---
 drivers/vfio/vfio_iommu_type1.c | 30 ++++++++++++++----------------
 1 file changed, 14 insertions(+), 16 deletions(-)

diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c
index 0b4dedaa9128..334a8240e1da 100644
--- a/drivers/vfio/vfio_iommu_type1.c
+++ b/drivers/vfio/vfio_iommu_type1.c
@@ -148,7 +148,7 @@ static int put_pfn(unsigned long pfn, int prot);
 static struct vfio_group *vfio_iommu_find_iommu_group(struct vfio_iommu *iommu,
 					       struct iommu_group *iommu_group);
 
-static void update_pinned_page_dirty_scope(struct vfio_iommu *iommu);
+static void promote_pinned_page_dirty_scope(struct vfio_iommu *iommu);
 /*
  * This code handles mapping and unmapping of user data buffers
  * into DMA'ble space using the IOMMU
@@ -714,7 +714,7 @@ static int vfio_iommu_type1_pin_pages(void *iommu_data,
 	group = vfio_iommu_find_iommu_group(iommu, iommu_group);
 	if (!group->pinned_page_dirty_scope) {
 		group->pinned_page_dirty_scope = true;
-		update_pinned_page_dirty_scope(iommu);
+		promote_pinned_page_dirty_scope(iommu);
 	}
 
 	goto pin_done;
@@ -1622,27 +1622,26 @@ static struct vfio_group *vfio_iommu_find_iommu_group(struct vfio_iommu *iommu,
 	return group;
 }
 
-static void update_pinned_page_dirty_scope(struct vfio_iommu *iommu)
+static void promote_pinned_page_dirty_scope(struct vfio_iommu *iommu)
 {
 	struct vfio_domain *domain;
 	struct vfio_group *group;
 
+	if (iommu->pinned_page_dirty_scope)
+		return;
+
 	list_for_each_entry(domain, &iommu->domain_list, next) {
 		list_for_each_entry(group, &domain->group_list, next) {
-			if (!group->pinned_page_dirty_scope) {
-				iommu->pinned_page_dirty_scope = false;
+			if (!group->pinned_page_dirty_scope)
 				return;
-			}
 		}
 	}
 
 	if (iommu->external_domain) {
 		domain = iommu->external_domain;
 		list_for_each_entry(group, &domain->group_list, next) {
-			if (!group->pinned_page_dirty_scope) {
-				iommu->pinned_page_dirty_scope = false;
+			if (!group->pinned_page_dirty_scope)
 				return;
-			}
 		}
 	}
 
@@ -2057,8 +2056,7 @@ static int vfio_iommu_type1_attach_group(void *iommu_data,
 			 * addition of a dirty tracking group.
 			 */
 			group->pinned_page_dirty_scope = true;
-			if (!iommu->pinned_page_dirty_scope)
-				update_pinned_page_dirty_scope(iommu);
+			promote_pinned_page_dirty_scope(iommu);
 			mutex_unlock(&iommu->lock);
 
 			return 0;
@@ -2341,7 +2339,7 @@ static void vfio_iommu_type1_detach_group(void *iommu_data,
 	struct vfio_iommu *iommu = iommu_data;
 	struct vfio_domain *domain;
 	struct vfio_group *group;
-	bool update_dirty_scope = false;
+	bool promote_dirty_scope = false;
 	LIST_HEAD(iova_copy);
 
 	mutex_lock(&iommu->lock);
@@ -2349,7 +2347,7 @@ static void vfio_iommu_type1_detach_group(void *iommu_data,
 	if (iommu->external_domain) {
 		group = find_iommu_group(iommu->external_domain, iommu_group);
 		if (group) {
-			update_dirty_scope = !group->pinned_page_dirty_scope;
+			promote_dirty_scope = !group->pinned_page_dirty_scope;
 			list_del(&group->next);
 			kfree(group);
 
@@ -2379,7 +2377,7 @@ static void vfio_iommu_type1_detach_group(void *iommu_data,
 			continue;
 
 		vfio_iommu_detach_group(domain, group);
-		update_dirty_scope = !group->pinned_page_dirty_scope;
+		promote_dirty_scope = !group->pinned_page_dirty_scope;
 		list_del(&group->next);
 		kfree(group);
 		/*
@@ -2415,8 +2413,8 @@ static void vfio_iommu_type1_detach_group(void *iommu_data,
 	 * Removal of a group without dirty tracking may allow the iommu scope
 	 * to be promoted.
 	 */
-	if (update_dirty_scope)
-		update_pinned_page_dirty_scope(iommu);
+	if (promote_dirty_scope)
+		promote_pinned_page_dirty_scope(iommu);
 	mutex_unlock(&iommu->lock);
 }
 
-- 
2.19.1