From 5c1cfb1c3948fe93a32dfcd75223dda0f1558bb7 Mon Sep 17 00:00:00 2001 From: Dong Jia Shi Date: Wed, 23 May 2018 04:56:43 +0200 Subject: 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 Signed-off-by: Dong Jia Shi Message-Id: <20180523025645.8978-3-bjsdjshi@linux.ibm.com> Signed-off-by: Cornelia Huck --- drivers/s390/cio/vfio_ccw_cp.c | 82 +++++++++++++++++++----------------------- 1 file changed, 36 insertions(+), 46 deletions(-) (limited to 'drivers/s390/cio') 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); -- cgit v1.2.3-59-g8ed1b