Commit e23a6217 authored by Nicolin Chen's avatar Nicolin Chen Committed by Alex Williamson
Browse files

iommufd/device: Add iommufd_access_detach() API 



Previously, the detach routine is only done by the destroy(). And it was
called by vfio_iommufd_emulated_unbind() when the device runs close(), so
all the mappings in iopt were cleaned in that setup, when the call trace
reaches this detach() routine.

Now, there's a need of a detach uAPI, meaning that it does not only need
a new iommufd_access_detach() API, but also requires access->ops->unmap()
call as a cleanup. So add one.

However, leaving that unprotected can introduce some potential of a race
condition during the pin_/unpin_pages() call, where access->ioas->iopt is
getting referenced. So, add an ioas_lock to protect the context of iopt
referencings.

Also, to allow the 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.

Reviewed-by: default avatarKevin Tian <kevin.tian@intel.com>
Reviewed-by: default avatarJason Gunthorpe <jgg@nvidia.com>
Tested-by: default avatarTerrence Xu <terrence.xu@intel.com>
Tested-by: default avatarNicolin Chen <nicolinc@nvidia.com>
Tested-by: default avatarMatthew Rosato <mjrosato@linux.ibm.com>
Tested-by: default avatarYanting Jiang <yanting.jiang@intel.com>
Tested-by: default avatarShameer Kolothum <shameerali.kolothum.thodi@huawei.com>
Tested-by: default avatarZhenzhong Duan <zhenzhong.duan@intel.com>
Signed-off-by: default avatarNicolin Chen <nicolinc@nvidia.com>
Signed-off-by: default avatarYi Liu <yi.l.liu@intel.com>
Link: https://lore.kernel.org/r/20230718135551.6592-15-yi.l.liu@intel.com


Signed-off-by: default avatarAlex Williamson <alex.williamson@redhat.com>
parent 9048c734

drivers/iommu/iommufd/device.c

+69 −5
Original line number Diff line number Diff line
@@ -486,6 +486,7 @@ iommufd_access_create(struct iommufd_ctx *ictx, 
	iommufd_ctx_get(ictx);

	iommufd_object_finalize(ictx, &access->obj);

	*id = access->obj.id;

	mutex_init(&access->ioas_lock);

	return access;

}

EXPORT_SYMBOL_NS_GPL(iommufd_access_create, IOMMUFD);
@@ -505,26 +506,60 @@ void iommufd_access_destroy(struct iommufd_access *access) 
}

EXPORT_SYMBOL_NS_GPL(iommufd_access_destroy, IOMMUFD);



void iommufd_access_detach(struct iommufd_access *access)

{

	struct iommufd_ioas *cur_ioas = access->ioas;



	mutex_lock(&access->ioas_lock);

	if (WARN_ON(!access->ioas))

		goto out;

	/*

	 * 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);

	}

	iopt_remove_access(&cur_ioas->iopt, access);

	refcount_dec(&cur_ioas->obj.users);

out:

	access->ioas_unpin = NULL;

	mutex_unlock(&access->ioas_lock);

}

EXPORT_SYMBOL_NS_GPL(iommufd_access_detach, IOMMUFD);



int iommufd_access_attach(struct iommufd_access *access, u32 ioas_id)

{

	struct iommufd_ioas *new_ioas;

	int rc = 0;



	if (access->ioas)

	mutex_lock(&access->ioas_lock);

	if (WARN_ON(access->ioas || access->ioas_unpin)) {

		mutex_unlock(&access->ioas_lock);

		return -EINVAL;

	}



	new_ioas = iommufd_get_ioas(access->ictx, ioas_id);

	if (IS_ERR(new_ioas))

	if (IS_ERR(new_ioas)) {

		mutex_unlock(&access->ioas_lock);

		return PTR_ERR(new_ioas);

	}



	rc = iopt_add_access(&new_ioas->iopt, access);

	if (rc) {

		mutex_unlock(&access->ioas_lock);

		iommufd_put_object(&new_ioas->obj);

		return rc;

	}

	iommufd_ref_to_users(&new_ioas->obj);



	access->ioas = new_ioas;

	access->ioas_unpin = new_ioas;

	mutex_unlock(&access->ioas_lock);

	return 0;

}

EXPORT_SYMBOL_NS_GPL(iommufd_access_attach, IOMMUFD);
@@ -579,8 +614,8 @@ void iommufd_access_notify_unmap(struct io_pagetable *iopt, unsigned long iova, 
void iommufd_access_unpin_pages(struct iommufd_access *access,

				unsigned long iova, unsigned long length)

{

	struct io_pagetable *iopt = &access->ioas->iopt;

	struct iopt_area_contig_iter iter;

	struct io_pagetable *iopt;

	unsigned long last_iova;

	struct iopt_area *area;
@@ -588,6 +623,17 @@ void iommufd_access_unpin_pages(struct iommufd_access *access, 
	    WARN_ON(check_add_overflow(iova, length - 1, &last_iova)))

		return;



	mutex_lock(&access->ioas_lock);

	/*

	 * The driver must be doing something wrong if it calls this before an

	 * iommufd_access_attach() or after an iommufd_access_detach().

	 */

	if (WARN_ON(!access->ioas_unpin)) {

		mutex_unlock(&access->ioas_lock);

		return;

	}

	iopt = &access->ioas_unpin->iopt;



	down_read(&iopt->iova_rwsem);

	iopt_for_each_contig_area(&iter, area, iopt, iova, last_iova)

		iopt_area_remove_access(
@@ -597,6 +643,7 @@ void iommufd_access_unpin_pages(struct iommufd_access *access, 
				min(last_iova, iopt_area_last_iova(area))));

	WARN_ON(!iopt_area_contig_done(&iter));

	up_read(&iopt->iova_rwsem);

	mutex_unlock(&access->ioas_lock);

}

EXPORT_SYMBOL_NS_GPL(iommufd_access_unpin_pages, IOMMUFD);
@@ -642,8 +689,8 @@ int iommufd_access_pin_pages(struct iommufd_access *access, unsigned long iova, 
			     unsigned long length, struct page **out_pages,

			     unsigned int flags)

{

	struct io_pagetable *iopt = &access->ioas->iopt;

	struct iopt_area_contig_iter iter;

	struct io_pagetable *iopt;

	unsigned long last_iova;

	struct iopt_area *area;

	int rc;
@@ -658,6 +705,13 @@ int iommufd_access_pin_pages(struct iommufd_access *access, unsigned long iova, 
	if (check_add_overflow(iova, length - 1, &last_iova))

		return -EOVERFLOW;



	mutex_lock(&access->ioas_lock);

	if (!access->ioas) {

		mutex_unlock(&access->ioas_lock);

		return -ENOENT;

	}

	iopt = &access->ioas->iopt;



	down_read(&iopt->iova_rwsem);

	iopt_for_each_contig_area(&iter, area, iopt, iova, last_iova) {

		unsigned long last = min(last_iova, iopt_area_last_iova(area));
@@ -688,6 +742,7 @@ int iommufd_access_pin_pages(struct iommufd_access *access, unsigned long iova, 
	}



	up_read(&iopt->iova_rwsem);

	mutex_unlock(&access->ioas_lock);

	return 0;



err_remove:
@@ -702,6 +757,7 @@ int iommufd_access_pin_pages(struct iommufd_access *access, unsigned long iova, 
						  iopt_area_last_iova(area))));

	}

	up_read(&iopt->iova_rwsem);

	mutex_unlock(&access->ioas_lock);

	return rc;

}

EXPORT_SYMBOL_NS_GPL(iommufd_access_pin_pages, IOMMUFD);
@@ -721,8 +777,8 @@ EXPORT_SYMBOL_NS_GPL(iommufd_access_pin_pages, IOMMUFD); 
int iommufd_access_rw(struct iommufd_access *access, unsigned long iova,

		      void *data, size_t length, unsigned int flags)

{

	struct io_pagetable *iopt = &access->ioas->iopt;

	struct iopt_area_contig_iter iter;

	struct io_pagetable *iopt;

	struct iopt_area *area;

	unsigned long last_iova;

	int rc;
@@ -732,6 +788,13 @@ int iommufd_access_rw(struct iommufd_access *access, unsigned long iova, 
	if (check_add_overflow(iova, length - 1, &last_iova))

		return -EOVERFLOW;



	mutex_lock(&access->ioas_lock);

	if (!access->ioas) {

		mutex_unlock(&access->ioas_lock);

		return -ENOENT;

	}

	iopt = &access->ioas->iopt;



	down_read(&iopt->iova_rwsem);

	iopt_for_each_contig_area(&iter, area, iopt, iova, last_iova) {

		unsigned long last = min(last_iova, iopt_area_last_iova(area));
@@ -758,6 +821,7 @@ int iommufd_access_rw(struct iommufd_access *access, unsigned long iova, 
		rc = -ENOENT;

err_out:

	up_read(&iopt->iova_rwsem);

	mutex_unlock(&access->ioas_lock);

	return rc;

}

EXPORT_SYMBOL_NS_GPL(iommufd_access_rw, IOMMUFD);

drivers/iommu/iommufd/iommufd_private.h

+2 −0
Original line number Diff line number Diff line
@@ -285,6 +285,8 @@ 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;

	unsigned long iova_alignment;

include/linux/iommufd.h

+1 −0
Original line number Diff line number Diff line
@@ -48,6 +48,7 @@ iommufd_access_create(struct iommufd_ctx *ictx, 
		      const struct iommufd_access_ops *ops, void *data, u32 *id);

void iommufd_access_destroy(struct iommufd_access *access);

int iommufd_access_attach(struct iommufd_access *access, u32 ioas_id);

void iommufd_access_detach(struct iommufd_access *access);



void iommufd_ctx_get(struct iommufd_ctx *ictx);