linux-kernel - [PATCH v2 1/2] iommu/virtio: Make use of ops->iotlb_sync

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Message-Id: <20230918-viommu-sync-map-v2-1-f33767f6cf7a@linux.ibm.com>
Date:   Mon, 18 Sep 2023 13:51:43 +0200
From:   Niklas Schnelle <schnelle@...ux.ibm.com>
To:     Jean-Philippe Brucker <jean-philippe@...aro.org>,
        Joerg Roedel <joro@...tes.org>, Will Deacon <will@...nel.org>,
        Robin Murphy <robin.murphy@....com>
Cc:     virtualization@...ts.linux-foundation.org, iommu@...ts.linux.dev,
        linux-kernel@...r.kernel.org,
        Niklas Schnelle <schnelle@...ux.ibm.com>
Subject: [PATCH v2 1/2] iommu/virtio: Make use of ops->iotlb_sync_map

Pull out the sync operation from viommu_map_pages() by implementing
ops->iotlb_sync_map. This allows the common IOMMU code to map multiple
elements of an sg with a single sync (see iommu_map_sg()). Furthermore,
it is also a requirement for IOMMU_CAP_DEFERRED_FLUSH.

Link: https://lore.kernel.org/lkml/20230726111433.1105665-1-schnelle@linux.ibm.com/
Signed-off-by: Niklas Schnelle <schnelle@...ux.ibm.com>
---
 drivers/iommu/virtio-iommu.c | 17 ++++++++++++++++-
 1 file changed, 16 insertions(+), 1 deletion(-)

diff --git a/drivers/iommu/virtio-iommu.c b/drivers/iommu/virtio-iommu.c
index 17dcd826f5c2..3649586f0e5c 100644
--- a/drivers/iommu/virtio-iommu.c
+++ b/drivers/iommu/virtio-iommu.c
@@ -189,6 +189,12 @@ static int viommu_sync_req(struct viommu_dev *viommu)
 	int ret;
 	unsigned long flags;
 
+	/*
+	 * .iotlb_sync_map and .flush_iotlb_all may be called before the viommu
+	 * is initialized e.g. via iommu_create_device_direct_mappings()
+	 */
+	if (!viommu)
+		return 0;
 	spin_lock_irqsave(&viommu->request_lock, flags);
 	ret = __viommu_sync_req(viommu);
 	if (ret)
@@ -843,7 +849,7 @@ static int viommu_map_pages(struct iommu_domain *domain, unsigned long iova,
 			.flags		= cpu_to_le32(flags),
 		};
 
-		ret = viommu_send_req_sync(vdomain->viommu, &map, sizeof(map));
+		ret = viommu_add_req(vdomain->viommu, &map, sizeof(map));
 		if (ret) {
 			viommu_del_mappings(vdomain, iova, end);
 			return ret;
@@ -912,6 +918,14 @@ static void viommu_iotlb_sync(struct iommu_domain *domain,
 	viommu_sync_req(vdomain->viommu);
 }
 
+static int viommu_iotlb_sync_map(struct iommu_domain *domain,
+				 unsigned long iova, size_t size)
+{
+	struct viommu_domain *vdomain = to_viommu_domain(domain);
+
+	return viommu_sync_req(vdomain->viommu);
+}
+
 static void viommu_get_resv_regions(struct device *dev, struct list_head *head)
 {
 	struct iommu_resv_region *entry, *new_entry, *msi = NULL;
@@ -1058,6 +1072,7 @@ static struct iommu_ops viommu_ops = {
 		.unmap_pages		= viommu_unmap_pages,
 		.iova_to_phys		= viommu_iova_to_phys,
 		.iotlb_sync		= viommu_iotlb_sync,
+		.iotlb_sync_map		= viommu_iotlb_sync_map,
 		.free			= viommu_domain_free,
 	}
 };

-- 
2.39.2