[RFT][PATCH v2 1/9] vfio: Make vfio_unpin_pages() return void

Nicolin Chen
2022-07-06T06:28:18Z

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 <hch@infradead.org>
Signed-off-by: Nicolin Chen <nicolinc@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);

--
2.17.1