linux-kernel - [PATCH 3/7] vfio: iommu_type1: Make an explicit "promote" semantic

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Date:   Thu, 10 Dec 2020 15:34:21 +0800
From:   Keqian Zhu <zhukeqian1@...wei.com>
To:     <linux-kernel@...r.kernel.org>,
        <linux-arm-kernel@...ts.infradead.org>,
        <iommu@...ts.linux-foundation.org>, <kvm@...r.kernel.org>,
        <kvmarm@...ts.cs.columbia.edu>,
        Alex Williamson <alex.williamson@...hat.com>,
        Cornelia Huck <cohuck@...hat.com>,
        Marc Zyngier <maz@...nel.org>, Will Deacon <will@...nel.org>,
        Robin Murphy <robin.murphy@....com>
CC:     Joerg Roedel <joro@...tes.org>,
        Catalin Marinas <catalin.marinas@....com>,
        James Morse <james.morse@....com>,
        Suzuki K Poulose <suzuki.poulose@....com>,
        Sean Christopherson <sean.j.christopherson@...el.com>,
        Julien Thierry <julien.thierry.kdev@...il.com>,
        Mark Brown <broonie@...nel.org>,
        "Thomas Gleixner" <tglx@...utronix.de>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Alexios Zavras <alexios.zavras@...el.com>,
        <wanghaibin.wang@...wei.com>, <jiangkunkun@...wei.com>,
        Keqian Zhu <zhukeqian1@...wei.com>
Subject: [PATCH 3/7] vfio: iommu_type1: Make an explicit "promote" semantic

When we want to promote pinned_page_scope of vfio_iommu, we
should call the "update" function to visit all vfio_group,
but when we want to downgrade it, we can set the flag directly.

Giving above, we can give an explicit "promote" semantic to
that function. BTW, if vfio_iommu has been promoted, then it
can return early.

Signed-off-by: Keqian Zhu <zhukeqian1@...wei.com>
---
 drivers/vfio/vfio_iommu_type1.c | 27 +++++++++++++--------------
 1 file changed, 13 insertions(+), 14 deletions(-)

diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c
index c52bcefba96b..bd9a94590ebc 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
@@ -719,7 +719,7 @@ 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;
@@ -1633,27 +1633,26 @@ 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;
-			}
 		}
 	}
 
@@ -2348,7 +2347,7 @@ 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);
@@ -2356,7 +2355,7 @@ 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);
 
@@ -2386,7 +2385,7 @@ 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);
 		/*
@@ -2422,8 +2421,8 @@ 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);
 }
 
-- 
2.23.0