Commit 5c1cfb1c authored by Dong Jia Shi's avatar Dong Jia Shi Committed by Cornelia Huck
Browse files

vfio: ccw: refactor and improve pfn_array_alloc_pin() 



This refactors pfn_array_alloc_pin() and also improves it by adding
defensive code in error handling so that calling pfn_array_unpin_free()
after error return won't lead to problem. This mainly does:
1. Merge pfn_array_pin() into pfn_array_alloc_pin(), since there is no
   other user of pfn_array_pin(). As a result, also remove kernel-doc
   for pfn_array_pin() and add/update kernel-doc for pfn_array_alloc_pin()
   and struct pfn_array.
2. For a vfio_pin_pages() failure, set pa->pa_nr to zero to indicate
   zero pages were pinned.
3. Set pa->pa_iova_pfn to NULL right after it was freed.

Suggested-by: default avatarPierre Morel <pmorel@linux.ibm.com>
Signed-off-by: default avatarDong Jia Shi <bjsdjshi@linux.ibm.com>
Message-Id: <20180523025645.8978-3-bjsdjshi@linux.ibm.com>
Signed-off-by: default avatarCornelia Huck <cohuck@redhat.com>
parent 80c57f7a

drivers/s390/cio/vfio_ccw_cp.c

+36 −46
Original line number Diff line number Diff line
@@ -29,7 +29,7 @@ struct pfn_array { 
	unsigned long		*pa_iova_pfn;

	/* Array that receives PFNs of the pages pinned. */

	unsigned long		*pa_pfn;

	/* Number of pages to pin/pinned from @pa_iova. */

	/* Number of pages pinned from @pa_iova. */

	int			pa_nr;

};
@@ -50,64 +50,33 @@ struct ccwchain { 
};



/*

 * pfn_array_pin() - pin user pages in memory

 * pfn_array_alloc_pin() - alloc memory for PFNs, then pin user pages in memory

 * @pa: pfn_array on which to perform the operation

 * @mdev: the mediated device to perform pin/unpin operations

 * @iova: target guest physical address

 * @len: number of bytes that should be pinned from @iova

 *

 * Attempt to pin user pages in memory.

 * Attempt to allocate memory for PFNs, and pin user pages in memory.

 *

 * Usage of pfn_array:

 * Any field in this structure should be initialized by caller.

 * We expect @pa->pa_nr > 0, and its value will be assigned by callee.

 * We expect (pa_nr == 0) and (pa_iova_pfn == NULL), any field in

 * this structure will be filled in by this function.

 *

 * Returns:

 *   Number of pages pinned on success.

 *   If @pa->pa_nr is 0 or negative, returns 0.

 *   If @pa->pa_nr is not 0, or @pa->pa_iova_pfn is not NULL initially,

 *   returns -EINVAL.

 *   If no pages were pinned, returns -errno.

 */

static int pfn_array_pin(struct pfn_array *pa, struct device *mdev)

{

	int i, ret;



	if (pa->pa_nr <= 0) {

		pa->pa_nr = 0;

		return 0;

	}



	pa->pa_iova_pfn[0] = pa->pa_iova >> PAGE_SHIFT;

	for (i = 1; i < pa->pa_nr; i++)

		pa->pa_iova_pfn[i] = pa->pa_iova_pfn[i - 1] + 1;



	ret = vfio_pin_pages(mdev, pa->pa_iova_pfn, pa->pa_nr,

			     IOMMU_READ | IOMMU_WRITE, pa->pa_pfn);



	if (ret > 0 && ret != pa->pa_nr) {

		vfio_unpin_pages(mdev, pa->pa_iova_pfn, ret);

		pa->pa_nr = 0;

		return 0;

	}



	return ret;

}



/* Unpin the pages before releasing the memory. */

static void pfn_array_unpin_free(struct pfn_array *pa, struct device *mdev)

{

	vfio_unpin_pages(mdev, pa->pa_iova_pfn, pa->pa_nr);

	pa->pa_nr = 0;

	kfree(pa->pa_iova_pfn);

}



/* Alloc memory for PFNs, then pin pages with them. */

static int pfn_array_alloc_pin(struct pfn_array *pa, struct device *mdev,

			       u64 iova, unsigned int len)

{

	int ret = 0;

	int i, ret = 0;



	if (!len)

		return 0;



	if (pa->pa_nr)

	if (pa->pa_nr || pa->pa_iova_pfn)

		return -EINVAL;



	pa->pa_iova = iova;
@@ -124,18 +93,39 @@ static int pfn_array_alloc_pin(struct pfn_array *pa, struct device *mdev, 
		return -ENOMEM;

	pa->pa_pfn = pa->pa_iova_pfn + pa->pa_nr;



	ret = pfn_array_pin(pa, mdev);

	pa->pa_iova_pfn[0] = pa->pa_iova >> PAGE_SHIFT;

	for (i = 1; i < pa->pa_nr; i++)

		pa->pa_iova_pfn[i] = pa->pa_iova_pfn[i - 1] + 1;



	if (ret > 0)

		return ret;

	else if (!ret)

	ret = vfio_pin_pages(mdev, pa->pa_iova_pfn, pa->pa_nr,

			     IOMMU_READ | IOMMU_WRITE, pa->pa_pfn);



	if (ret < 0) {

		goto err_out;

	} else if (ret > 0 && ret != pa->pa_nr) {

		vfio_unpin_pages(mdev, pa->pa_iova_pfn, ret);

		ret = -EINVAL;

		goto err_out;

	}



	return ret;



err_out:

	pa->pa_nr = 0;

	kfree(pa->pa_iova_pfn);

	pa->pa_iova_pfn = NULL;



	return ret;

}



/* Unpin the pages before releasing the memory. */

static void pfn_array_unpin_free(struct pfn_array *pa, struct device *mdev)

{

	vfio_unpin_pages(mdev, pa->pa_iova_pfn, pa->pa_nr);

	pa->pa_nr = 0;

	kfree(pa->pa_iova_pfn);

}



static int pfn_array_table_init(struct pfn_array_table *pat, int nr)

{

	pat->pat_pa = kcalloc(nr, sizeof(*pat->pat_pa), GFP_KERNEL);

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