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Message-ID: <58b67ca78925186b246ce8ed3639a1c92e56f98a.1678284812.git.nicolinc@nvidia.com>
Date: Wed, 8 Mar 2023 06:26:00 -0800
From: Nicolin Chen <nicolinc@...dia.com>
To: <jgg@...dia.com>, <kevin.tian@...el.com>, <joro@...tes.org>,
<will@...nel.org>, <robin.murphy@....com>,
<alex.williamson@...hat.com>, <shuah@...nel.org>
CC: <yi.l.liu@...el.com>, <linux-kernel@...r.kernel.org>,
<iommu@...ts.linux.dev>, <kvm@...r.kernel.org>,
<linux-kselftest@...r.kernel.org>, <mjrosato@...ux.ibm.com>,
<farman@...ux.ibm.com>
Subject: [PATCH v4 3/5] iommufd: Add replace support in iommufd_access_set_ioas()
Support an access->ioas replacement in iommufd_access_set_ioas(), which
sets the access->ioas to NULL provisionally so that any further incoming
iommufd_access_pin_pages() callback can be blocked.
Then, call access->ops->unmap() to clean up the entire iopt. To allow an
iommufd_access_unpin_pages() callback to happen via this unmap() call,
add an ioas_unpin pointer so the unpin routine won't be affected by the
"access->ioas = NULL" trick above.
Suggested-by: Jason Gunthorpe <jgg@...dia.com>
Signed-off-by: Nicolin Chen <nicolinc@...dia.com>
---
drivers/iommu/iommufd/device.c | 17 +++++++++++++++--
drivers/iommu/iommufd/iommufd_private.h | 1 +
2 files changed, 16 insertions(+), 2 deletions(-)
diff --git a/drivers/iommu/iommufd/device.c b/drivers/iommu/iommufd/device.c
index 612a5f424bd7..c10e02f6a0be 100644
--- a/drivers/iommu/iommufd/device.c
+++ b/drivers/iommu/iommufd/device.c
@@ -727,11 +727,24 @@ int iommufd_access_set_ioas(struct iommufd_access *access, u32 ioas_id)
iommufd_ref_to_users(obj);
}
+ /*
+ * Set ioas to NULL to block any further iommufd_access_pin_pages().
+ * iommufd_access_unpin_pages() can continue using access->ioas_unpin.
+ */
+ access->ioas = NULL;
+
+ if (access->ops->unmap) {
+ mutex_unlock(&access->ioas_lock);
+ access->ops->unmap(access->data, 0, ULONG_MAX);
+ mutex_lock(&access->ioas_lock);
+ }
+
if (cur_ioas) {
iopt_remove_access(&cur_ioas->iopt, access);
refcount_dec(&cur_ioas->obj.users);
}
+ access->ioas_unpin = new_ioas;
access->ioas = new_ioas;
mutex_unlock(&access->ioas_lock);
@@ -805,11 +818,11 @@ void iommufd_access_unpin_pages(struct iommufd_access *access,
return;
mutex_lock(&access->ioas_lock);
- if (!access->ioas) {
+ if (!access->ioas_unpin) {
mutex_unlock(&access->ioas_lock);
return;
}
- iopt = &access->ioas->iopt;
+ iopt = &access->ioas_unpin->iopt;
down_read(&iopt->iova_rwsem);
iopt_for_each_contig_area(&iter, area, iopt, iova, last_iova)
diff --git a/drivers/iommu/iommufd/iommufd_private.h b/drivers/iommu/iommufd/iommufd_private.h
index db1ead8ff9d0..b18f843ad6a4 100644
--- a/drivers/iommu/iommufd/iommufd_private.h
+++ b/drivers/iommu/iommufd/iommufd_private.h
@@ -312,6 +312,7 @@ struct iommufd_access {
struct iommufd_object obj;
struct iommufd_ctx *ictx;
struct iommufd_ioas *ioas;
+ struct iommufd_ioas *ioas_unpin;
struct mutex ioas_lock;
const struct iommufd_access_ops *ops;
void *data;
--
2.39.2
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