Commit e4f3f18b authored by Eric Farman's avatar Eric Farman Committed by Cornelia Huck
Browse files

s390/cio: Split pfn_array_alloc_pin into pieces 



The pfn_array_alloc_pin routine is doing too much.  Today, it does the
alloc of the pfn_array struct and its member arrays, builds the iova
address lists out of a contiguous piece of guest memory, and asks vfio
to pin the resulting pages.

Let's effectively revert a significant portion of commit 5c1cfb1c
("vfio: ccw: refactor and improve pfn_array_alloc_pin()") such that we
break pfn_array_alloc_pin() into its component pieces, and have one
routine that allocates/populates the pfn_array structs, and another
that actually pins the memory.  In the future, we will be able to
handle scenarios where pinning memory isn't actually appropriate.

Signed-off-by: default avatarEric Farman <farman@linux.ibm.com>
Message-Id: <20190514234248.36203-4-farman@linux.ibm.com>
Reviewed-by: default avatarFarhan Ali <alifm@linux.ibm.com>
Signed-off-by: default avatarCornelia Huck <cohuck@redhat.com>
parent 4e31d6ae

drivers/s390/cio/vfio_ccw_cp.c

+46 −18
Original line number Diff line number Diff line
@@ -50,28 +50,25 @@ struct ccwchain { 
};



/*

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

 * pfn_array_alloc() - alloc memory for PFNs

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

 * Attempt to allocate memory for PFNs.

 *

 * Usage of pfn_array:

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

 *   returns -EINVAL.

 *   If no pages were pinned, returns -errno.

 *         0 if PFNs are allocated

 *   -EINVAL if pa->pa_nr is not initially zero, or pa->pa_iova_pfn is not NULL

 *   -ENOMEM if alloc failed

 */

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

			       u64 iova, unsigned int len)

static int pfn_array_alloc(struct pfn_array *pa, u64 iova, unsigned int len)

{

	int i, ret = 0;

	int i;



	if (!len)

		return 0;
@@ -97,6 +94,22 @@ static int pfn_array_alloc_pin(struct pfn_array *pa, struct device *mdev, 
	for (i = 1; i < pa->pa_nr; i++)

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



	return 0;

}



/*

 * pfn_array_pin() - Pin user pages in memory

 * @pa: pfn_array on which to perform the operation

 * @mdev: the mediated device to perform pin operations

 *

 * Returns number of pages pinned upon success.

 * If the pin request partially succeeds, or fails completely,

 * all pages are left unpinned and a negative error value is returned.

 */

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

{

	int ret = 0;



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

			     IOMMU_READ | IOMMU_WRITE, pa->pa_pfn);
@@ -112,8 +125,6 @@ static int pfn_array_alloc_pin(struct pfn_array *pa, struct device *mdev, 


err_out:

	pa->pa_nr = 0;

	kfree(pa->pa_iova_pfn);

	pa->pa_iova_pfn = NULL;



	return ret;

}
@@ -121,6 +132,8 @@ err_out: 
/* Unpin the pages before releasing the memory. */

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

{

	/* Only unpin if any pages were pinned to begin with */

	if (pa->pa_nr)

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

	pa->pa_nr = 0;

	kfree(pa->pa_iova_pfn);
@@ -209,9 +222,15 @@ static long copy_from_iova(struct device *mdev, 
	int i, ret;

	unsigned long l, m;



	ret = pfn_array_alloc_pin(&pa, mdev, iova, n);

	if (ret <= 0)

	ret = pfn_array_alloc(&pa, iova, n);

	if (ret < 0)

		return ret;



	ret = pfn_array_pin(&pa, mdev);

	if (ret < 0) {

		pfn_array_unpin_free(&pa, mdev);

		return ret;

	}



	l = n;

	for (i = 0; i < pa.pa_nr; i++) {
@@ -560,7 +579,11 @@ static int ccwchain_fetch_direct(struct ccwchain *chain, 
	if (ret)

		goto out_init;



	ret = pfn_array_alloc_pin(pat->pat_pa, cp->mdev, ccw->cda, ccw->count);

	ret = pfn_array_alloc(pat->pat_pa, ccw->cda, ccw->count);

	if (ret < 0)

		goto out_unpin;



	ret = pfn_array_pin(pat->pat_pa, cp->mdev);

	if (ret < 0)

		goto out_unpin;
@@ -590,6 +613,7 @@ static int ccwchain_fetch_idal(struct ccwchain *chain, 
{

	struct ccw1 *ccw;

	struct pfn_array_table *pat;

	struct pfn_array *pa;

	unsigned long *idaws;

	u64 idaw_iova;

	unsigned int idaw_nr, idaw_len;
@@ -628,9 +652,13 @@ static int ccwchain_fetch_idal(struct ccwchain *chain, 


	for (i = 0; i < idaw_nr; i++) {

		idaw_iova = *(idaws + i);

		pa = pat->pat_pa + i;



		ret = pfn_array_alloc(pa, idaw_iova, 1);

		if (ret < 0)

			goto out_free_idaws;



		ret = pfn_array_alloc_pin(pat->pat_pa + i, cp->mdev,

					  idaw_iova, 1);

		ret = pfn_array_pin(pa, cp->mdev);

		if (ret < 0)

			goto out_free_idaws;

	}

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