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authorDong Jia Shi <bjsdjshi@linux.ibm.com>2018-05-23 04:56:43 +0200
committerCornelia Huck <cohuck@redhat.com>2018-05-29 09:27:42 +0200
commit5c1cfb1c3948fe93a32dfcd75223dda0f1558bb7 (patch)
tree0bdfe7d0f47217483eba702bdada9a2e9d860ae8 /drivers/s390
parent80c57f7a075b0c53944113e42ce114d8bf0977e4 (diff)
downloadlinux-5c1cfb1c3948fe93a32dfcd75223dda0f1558bb7.tar.gz
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: Pierre Morel <pmorel@linux.ibm.com> Signed-off-by: Dong Jia Shi <bjsdjshi@linux.ibm.com> Message-Id: <20180523025645.8978-3-bjsdjshi@linux.ibm.com> Signed-off-by: Cornelia Huck <cohuck@redhat.com>
Diffstat (limited to 'drivers/s390')
-rw-r--r--drivers/s390/cio/vfio_ccw_cp.c82
1 files changed, 36 insertions, 46 deletions
diff --git a/drivers/s390/cio/vfio_ccw_cp.c b/drivers/s390/cio/vfio_ccw_cp.c
index c532939c1c3f..b0f20230fc72 100644
--- a/drivers/s390/cio/vfio_ccw_cp.c
+++ b/drivers/s390/cio/vfio_ccw_cp.c
@@ -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;
+
+ ret = vfio_pin_pages(mdev, pa->pa_iova_pfn, pa->pa_nr,
+ IOMMU_READ | IOMMU_WRITE, pa->pa_pfn);
- if (ret > 0)
- return ret;
- else if (!ret)
+ 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);