netdev - [PATCH 1/5] iommu: Replace uses of IOMMU_CAP_CACHE_COHERENCY with dev_is_dma

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Message-Id: <1-v1-ef02c60ddb76+12ca2-intel_no_snoop_jgg@nvidia.com>
Date:   Tue,  5 Apr 2022 13:16:00 -0300
From:   Jason Gunthorpe <jgg@...dia.com>
To:     Alex Williamson <alex.williamson@...hat.com>,
        Lu Baolu <baolu.lu@...ux.intel.com>,
        Christian Benvenuti <benve@...co.com>,
        Cornelia Huck <cohuck@...hat.com>,
        David Woodhouse <dwmw2@...radead.org>,
        Gerald Schaefer <gerald.schaefer@...ux.ibm.com>,
        iommu@...ts.linux-foundation.org, Jason Wang <jasowang@...hat.com>,
        Joerg Roedel <joro@...tes.org>, kvm@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org,
        linux-arm-msm@...r.kernel.org, linux-rdma@...r.kernel.org,
        linux-s390@...r.kernel.org,
        Matthew Rosato <mjrosato@...ux.ibm.com>,
        "Michael S. Tsirkin" <mst@...hat.com>,
        Nelson Escobar <neescoba@...co.com>, netdev@...r.kernel.org,
        Rob Clark <robdclark@...il.com>,
        Robin Murphy <robin.murphy@....com>,
        Suravee Suthikulpanit <suravee.suthikulpanit@....com>,
        virtualization@...ts.linux-foundation.org,
        Will Deacon <will@...nel.org>
Cc:     Christoph Hellwig <hch@....de>,
        "Tian, Kevin" <kevin.tian@...el.com>
Subject: [PATCH 1/5] iommu: Replace uses of IOMMU_CAP_CACHE_COHERENCY with dev_is_dma_coherent()

vdpa and usnic are trying to test if IOMMU_CACHE is supported. The correct
way to do this is via dev_is_dma_coherent() like the DMA API does. If
IOMMU_CACHE is not supported then these drivers won't work as they don't
call any coherency-restoring routines around their DMAs.

Signed-off-by: Jason Gunthorpe <jgg@...dia.com>
---
 drivers/infiniband/hw/usnic/usnic_uiom.c | 16 +++++++---------
 drivers/vhost/vdpa.c                     |  3 ++-
 2 files changed, 9 insertions(+), 10 deletions(-)

diff --git a/drivers/infiniband/hw/usnic/usnic_uiom.c b/drivers/infiniband/hw/usnic/usnic_uiom.c
index 760b254ba42d6b..24d118198ac756 100644
--- a/drivers/infiniband/hw/usnic/usnic_uiom.c
+++ b/drivers/infiniband/hw/usnic/usnic_uiom.c
@@ -42,6 +42,7 @@
 #include <linux/list.h>
 #include <linux/pci.h>
 #include <rdma/ib_verbs.h>
+#include <linux/dma-map-ops.h>
 
 #include "usnic_log.h"
 #include "usnic_uiom.h"
@@ -474,6 +475,12 @@ int usnic_uiom_attach_dev_to_pd(struct usnic_uiom_pd *pd, struct device *dev)
 	struct usnic_uiom_dev *uiom_dev;
 	int err;
 
+	if (!dev_is_dma_coherent(dev)) {
+		usnic_err("IOMMU of %s does not support cache coherency\n",
+				dev_name(dev));
+		return -EINVAL;
+	}
+
 	uiom_dev = kzalloc(sizeof(*uiom_dev), GFP_ATOMIC);
 	if (!uiom_dev)
 		return -ENOMEM;
@@ -483,13 +490,6 @@ int usnic_uiom_attach_dev_to_pd(struct usnic_uiom_pd *pd, struct device *dev)
 	if (err)
 		goto out_free_dev;
 
-	if (!iommu_capable(dev->bus, IOMMU_CAP_CACHE_COHERENCY)) {
-		usnic_err("IOMMU of %s does not support cache coherency\n",
-				dev_name(dev));
-		err = -EINVAL;
-		goto out_detach_device;
-	}
-
 	spin_lock(&pd->lock);
 	list_add_tail(&uiom_dev->link, &pd->devs);
 	pd->dev_cnt++;
@@ -497,8 +497,6 @@ int usnic_uiom_attach_dev_to_pd(struct usnic_uiom_pd *pd, struct device *dev)
 
 	return 0;
 
-out_detach_device:
-	iommu_detach_device(pd->domain, dev);
 out_free_dev:
 	kfree(uiom_dev);
 	return err;
diff --git a/drivers/vhost/vdpa.c b/drivers/vhost/vdpa.c
index 4c2f0bd062856a..05ea5800febc37 100644
--- a/drivers/vhost/vdpa.c
+++ b/drivers/vhost/vdpa.c
@@ -22,6 +22,7 @@
 #include <linux/vdpa.h>
 #include <linux/nospec.h>
 #include <linux/vhost.h>
+#include <linux/dma-map-ops.h>
 
 #include "vhost.h"
 
@@ -929,7 +930,7 @@ static int vhost_vdpa_alloc_domain(struct vhost_vdpa *v)
 	if (!bus)
 		return -EFAULT;
 
-	if (!iommu_capable(bus, IOMMU_CAP_CACHE_COHERENCY))
+	if (!dev_is_dma_coherent(dma_dev))
 		return -ENOTSUPP;
 
 	v->domain = iommu_domain_alloc(bus);
-- 
2.35.1