diff mbox series

[v3,4/5] iommufd: Add replace support in iommufd_access_set_ioas()

Message ID a104b334d3cc148620ac1f2aa465fc14be556e63.1677288789.git.nicolinc@nvidia.com
State New
Headers
Series Add IO page table replacement support for emulated pathway |

Commit Message

Nicolin Chen Feb. 25, 2023, 1:51 a.m. UTC 
  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@nvidia.com>
Signed-off-by: Nicolin Chen <nicolinc@nvidia.com>
---
 drivers/iommu/iommufd/device.c          | 15 +++++++++++++--
 drivers/iommu/iommufd/iommufd_private.h |  1 +
 2 files changed, 14 insertions(+), 2 deletions(-)

Comments

Tian, Kevin March 2, 2023, 8:23 a.m. UTC | #1 
> From: Nicolin Chen <nicolinc@nvidia.com>
> Sent: Saturday, February 25, 2023 9:52 AM
> 
> +	/*
> +	 * 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;
> +
> +	mutex_unlock(&access->ioas_lock);
> +	access->ops->unmap(access->data, 0, ULONG_MAX);
> +	mutex_lock(&access->ioas_lock);

This should check whether @unmap is valid.
Nicolin Chen March 2, 2023, 11:53 p.m. UTC | #2 
On Thu, Mar 02, 2023 at 08:23:54AM +0000, Tian, Kevin wrote:
> External email: Use caution opening links or attachments
> 
> 
> > From: Nicolin Chen <nicolinc@nvidia.com>
> > Sent: Saturday, February 25, 2023 9:52 AM
> >
> > +     /*
> > +      * 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;
> > +
> > +     mutex_unlock(&access->ioas_lock);
> > +     access->ops->unmap(access->data, 0, ULONG_MAX);
> > +     mutex_lock(&access->ioas_lock);
> 
> This should check whether @unmap is valid.

Will change to 
+	if (access->ops->unmap) {
+		mutex_unlock(&access->ioas_lock);
+		access->ops->unmap(access->data, 0, ULONG_MAX);
+		mutex_lock(&access->ioas_lock);
+	}

Thanks!
Nic
diff mbox series

Patch

diff --git a/drivers/iommu/iommufd/device.c b/drivers/iommu/iommufd/device.c
index a955ebd4bd5d..c44d6e7a2ed7 100644
--- a/drivers/iommu/iommufd/device.c
+++ b/drivers/iommu/iommufd/device.c
@@ -712,11 +712,22 @@  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;
+
+	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);
 
@@ -790,11 +801,11 @@  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 94e88377a7fc..44e77ea9c399 100644
--- a/drivers/iommu/iommufd/iommufd_private.h
+++ b/drivers/iommu/iommufd/iommufd_private.h
@@ -311,6 +311,7 @@  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;