Reviewed-by: Kirti Wankhede <kwankh...@nvidia.com>

On 7/6/2022 11:57 AM, Nicolin Chen wrote:
There's only one caller that checks its return value with a WARN_ON_ONCE,
while all other callers do not check return value at all. So simplify the
API to return void by embedding similar WARN_ON_ONCEs.

Suggested-by: Christoph Hellwig <h...@infradead.org>
Signed-off-by: Nicolin Chen <nicol...@nvidia.com>
---
  .../driver-api/vfio-mediated-device.rst       |  2 +-
  drivers/gpu/drm/i915/gvt/kvmgt.c              |  5 +---
  drivers/vfio/vfio.c                           | 24 ++++++++-----------
  drivers/vfio/vfio.h                           |  2 +-
  drivers/vfio/vfio_iommu_type1.c               | 16 ++++++-------
  include/linux/vfio.h                          |  4 ++--
  6 files changed, 23 insertions(+), 30 deletions(-)

diff --git a/Documentation/driver-api/vfio-mediated-device.rst 
b/Documentation/driver-api/vfio-mediated-device.rst
index 1c57815619fd..b0fdf76b339a 100644
--- a/Documentation/driver-api/vfio-mediated-device.rst
+++ b/Documentation/driver-api/vfio-mediated-device.rst
@@ -265,7 +265,7 @@ driver::
        int vfio_pin_pages(struct vfio_device *device, unsigned long *user_pfn,
                                  int npage, int prot, unsigned long *phys_pfn);
- int vfio_unpin_pages(struct vfio_device *device, unsigned long *user_pfn,
+       void vfio_unpin_pages(struct vfio_device *device, unsigned long 
*user_pfn,
                                    int npage);
These functions call back into the back-end IOMMU module by using the pin_pages
diff --git a/drivers/gpu/drm/i915/gvt/kvmgt.c b/drivers/gpu/drm/i915/gvt/kvmgt.c
index e2f6c56ab342..8c67c9aba82d 100644
--- a/drivers/gpu/drm/i915/gvt/kvmgt.c
+++ b/drivers/gpu/drm/i915/gvt/kvmgt.c
@@ -231,18 +231,15 @@ static void intel_gvt_cleanup_vgpu_type_groups(struct 
intel_gvt *gvt)
  static void gvt_unpin_guest_page(struct intel_vgpu *vgpu, unsigned long gfn,
                unsigned long size)
  {
-       struct drm_i915_private *i915 = vgpu->gvt->gt->i915;
        int total_pages;
        int npage;
-       int ret;
total_pages = roundup(size, PAGE_SIZE) / PAGE_SIZE; for (npage = 0; npage < total_pages; npage++) {
                unsigned long cur_gfn = gfn + npage;
- ret = vfio_unpin_pages(&vgpu->vfio_device, &cur_gfn, 1);
-               drm_WARN_ON(&i915->drm, ret != 1);
+               vfio_unpin_pages(&vgpu->vfio_device, &cur_gfn, 1);
        }
  }
diff --git a/drivers/vfio/vfio.c b/drivers/vfio/vfio.c
index 61e71c1154be..01f45ec70a3d 100644
--- a/drivers/vfio/vfio.c
+++ b/drivers/vfio/vfio.c
@@ -1959,31 +1959,27 @@ EXPORT_SYMBOL(vfio_pin_pages);
   *               PFNs should not be greater than VFIO_PIN_PAGES_MAX_ENTRIES.
   * @npage [in]   : count of elements in user_pfn array.  This count should not
   *                 be greater than VFIO_PIN_PAGES_MAX_ENTRIES.
- * Return error or number of pages unpinned.
   */
-int vfio_unpin_pages(struct vfio_device *device, unsigned long *user_pfn,
-                    int npage)
+void vfio_unpin_pages(struct vfio_device *device, unsigned long *user_pfn,
+                     int npage)
  {
        struct vfio_container *container;
        struct vfio_iommu_driver *driver;
-       int ret;
- if (!user_pfn || !npage || !vfio_assert_device_open(device))
-               return -EINVAL;
+       if (WARN_ON_ONCE(!user_pfn || !npage || 
!vfio_assert_device_open(device)))
+               return;
- if (npage > VFIO_PIN_PAGES_MAX_ENTRIES)
-               return -E2BIG;
+       if (WARN_ON_ONCE(npage > VFIO_PIN_PAGES_MAX_ENTRIES))
+               return;
/* group->container cannot change while a vfio device is open */
        container = device->group->container;
        driver = container->iommu_driver;
-       if (likely(driver && driver->ops->unpin_pages))
-               ret = driver->ops->unpin_pages(container->iommu_data, user_pfn,
-                                              npage);
-       else
-               ret = -ENOTTY;
- return ret;
+       if (WARN_ON_ONCE(unlikely(!driver || !driver->ops->unpin_pages)))
+               return;
+
+       driver->ops->unpin_pages(container->iommu_data, user_pfn, npage);
  }
  EXPORT_SYMBOL(vfio_unpin_pages);
diff --git a/drivers/vfio/vfio.h b/drivers/vfio/vfio.h
index a67130221151..bef4edf58138 100644
--- a/drivers/vfio/vfio.h
+++ b/drivers/vfio/vfio.h
@@ -53,7 +53,7 @@ struct vfio_iommu_driver_ops {
                                     unsigned long *user_pfn,
                                     int npage, int prot,
                                     unsigned long *phys_pfn);
-       int             (*unpin_pages)(void *iommu_data,
+       void            (*unpin_pages)(void *iommu_data,
                                       unsigned long *user_pfn, int npage);
        int             (*register_notifier)(void *iommu_data,
                                             unsigned long *events,
diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c
index c13b9290e357..08613edaf722 100644
--- a/drivers/vfio/vfio_iommu_type1.c
+++ b/drivers/vfio/vfio_iommu_type1.c
@@ -948,20 +948,19 @@ static int vfio_iommu_type1_pin_pages(void *iommu_data,
        return ret;
  }
-static int vfio_iommu_type1_unpin_pages(void *iommu_data,
-                                       unsigned long *user_pfn,
-                                       int npage)
+static void vfio_iommu_type1_unpin_pages(void *iommu_data,
+                                        unsigned long *user_pfn, int npage)
  {
        struct vfio_iommu *iommu = iommu_data;
        bool do_accounting;
        int i;
- if (!iommu || !user_pfn || npage <= 0)
-               return -EINVAL;
+       if (WARN_ON_ONCE(!iommu || !user_pfn || npage <= 0))
+               return;
/* Supported for v2 version only */
-       if (!iommu->v2)
-               return -EACCES;
+       if (WARN_ON_ONCE(!iommu->v2))
+               return;
mutex_lock(&iommu->lock); @@ -979,7 +978,8 @@ static int vfio_iommu_type1_unpin_pages(void *iommu_data,
        }
mutex_unlock(&iommu->lock);
-       return i > 0 ? i : -EINVAL;
+
+       WARN_ON_ONCE(i != npage);
  }
static long vfio_sync_unpin(struct vfio_dma *dma, struct vfio_domain *domain,
diff --git a/include/linux/vfio.h b/include/linux/vfio.h
index 49580fa2073a..d0844ecdc961 100644
--- a/include/linux/vfio.h
+++ b/include/linux/vfio.h
@@ -149,8 +149,8 @@ bool vfio_file_has_dev(struct file *file, struct 
vfio_device *device);
int vfio_pin_pages(struct vfio_device *device, unsigned long *user_pfn,
                   int npage, int prot, unsigned long *phys_pfn);
-int vfio_unpin_pages(struct vfio_device *device, unsigned long *user_pfn,
-                    int npage);
+void vfio_unpin_pages(struct vfio_device *device, unsigned long *user_pfn,
+                     int npage);
  int vfio_dma_rw(struct vfio_device *device, dma_addr_t user_iova,
                void *data, size_t len, bool write);

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