vfio/platform: return info for device memory mapped IO regions

This patch enables the IOCTLs VFIO_DEVICE_GET_REGION_INFO ioctl call,
which allows the user to learn about the available MMIO resources of
a device.

Signed-off-by: Antonios Motakis <a.motakis@virtualopensystems.com>
Signed-off-by: Baptiste Reynal <b.reynal@virtualopensystems.com>
Reviewed-by: Eric Auger <eric.auger@linaro.org>
Tested-by: Eric Auger <eric.auger@linaro.org>
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>

2 files changed, 124 insertions, 4 deletions

diff --git a/drivers/vfio/platform/vfio_platform_common.c b/drivers/vfio/platform/vfio_platform_common.c
index c2f853a3b3dd..47f6309b4889 100644
--- a/drivers/vfio/platform/vfio_platform_common.c
+++ b/drivers/vfio/platform/vfio_platform_common.c
@@ -23,17 +23,97 @@
 
 #include "vfio_platform_private.h"
 
+static DEFINE_MUTEX(driver_lock);
+
+static int vfio_platform_regions_init(struct vfio_platform_device *vdev)
+{
+        int cnt = 0, i;
+
+        while (vdev->get_resource(vdev, cnt))
+                cnt++;
+
+        vdev->regions = kcalloc(cnt, sizeof(struct vfio_platform_region),
+                                GFP_KERNEL);
+        if (!vdev->regions)
+                return -ENOMEM;
+
+        for (i = 0; i < cnt;  i++) {
+                struct resource *res =
+                        vdev->get_resource(vdev, i);
+
+                if (!res)
+                        goto err;
+
+                vdev->regions[i].addr = res->start;
+                vdev->regions[i].size = resource_size(res);
+                vdev->regions[i].flags = 0;
+
+                switch (resource_type(res)) {
+                case IORESOURCE_MEM:
+                        vdev->regions[i].type = VFIO_PLATFORM_REGION_TYPE_MMIO;
+                        break;
+                case IORESOURCE_IO:
+                        vdev->regions[i].type = VFIO_PLATFORM_REGION_TYPE_PIO;
+                        break;
+                default:
+                        goto err;
+                }
+        }
+
+        vdev->num_regions = cnt;
+
+        return 0;
+err:
+        kfree(vdev->regions);
+        return -EINVAL;
+}
+
+static void vfio_platform_regions_cleanup(struct vfio_platform_device *vdev)
+{
+        vdev->num_regions = 0;
+        kfree(vdev->regions);
+}
+
 static void vfio_platform_release(void *device_data)
 {
+        struct vfio_platform_device *vdev = device_data;
+
+        mutex_lock(&driver_lock);
+
+        if (!(--vdev->refcnt)) {
+                vfio_platform_regions_cleanup(vdev);
+        }
+
+        mutex_unlock(&driver_lock);
+
         module_put(THIS_MODULE);
 }
 
 static int vfio_platform_open(void *device_data)
 {
+        struct vfio_platform_device *vdev = device_data;
+        int ret;
+
         if (!try_module_get(THIS_MODULE))
                 return -ENODEV;
 
+        mutex_lock(&driver_lock);
+
+        if (!vdev->refcnt) {
+                ret = vfio_platform_regions_init(vdev);
+                if (ret)
+                        goto err_reg;
+        }
+
+        vdev->refcnt++;
+
+        mutex_unlock(&driver_lock);
         return 0;
+
+err_reg:
+        mutex_unlock(&driver_lock);
+        module_put(THIS_MODULE);
+        return ret;
 }
 
 static long vfio_platform_ioctl(void *device_data,
@@ -54,15 +134,33 @@ static long vfio_platform_ioctl(void *device_data,
                         return -EINVAL;
 
                 info.flags = vdev->flags;
-                info.num_regions = 0;
+                info.num_regions = vdev->num_regions;
                 info.num_irqs = 0;
 
                 return copy_to_user((void __user *)arg, &info, minsz);
 
-        } else if (cmd == VFIO_DEVICE_GET_REGION_INFO)
-                return -EINVAL;
+        } else if (cmd == VFIO_DEVICE_GET_REGION_INFO) {
+                struct vfio_region_info info;
+
+                minsz = offsetofend(struct vfio_region_info, offset);
+
+                if (copy_from_user(&info, (void __user *)arg, minsz))
+                        return -EFAULT;
+
+                if (info.argsz < minsz)
+                        return -EINVAL;
+
+                if (info.index >= vdev->num_regions)
+                        return -EINVAL;
+
+                /* map offset to the physical address  */
+                info.offset = VFIO_PLATFORM_INDEX_TO_OFFSET(info.index);
+                info.size = vdev->regions[info.index].size;
+                info.flags = vdev->regions[info.index].flags;
+
+                return copy_to_user((void __user *)arg, &info, minsz);
 
-        else if (cmd == VFIO_DEVICE_GET_IRQ_INFO)
+        } else if (cmd == VFIO_DEVICE_GET_IRQ_INFO)
                 return -EINVAL;
 
         else if (cmd == VFIO_DEVICE_SET_IRQS)
diff --git a/drivers/vfio/platform/vfio_platform_private.h b/drivers/vfio/platform/vfio_platform_private.h
index c04698872440..3551f6d97fc3 100644
--- a/drivers/vfio/platform/vfio_platform_private.h
+++ b/drivers/vfio/platform/vfio_platform_private.h
@@ -18,7 +18,29 @@
 #include <linux/types.h>
 #include <linux/interrupt.h>
 
+#define VFIO_PLATFORM_OFFSET_SHIFT   40
+#define VFIO_PLATFORM_OFFSET_MASK (((u64)(1) << VFIO_PLATFORM_OFFSET_SHIFT) - 1)
+
+#define VFIO_PLATFORM_OFFSET_TO_INDEX(off)      \
+        (off >> VFIO_PLATFORM_OFFSET_SHIFT)
+
+#define VFIO_PLATFORM_INDEX_TO_OFFSET(index)    \
+        ((u64)(index) << VFIO_PLATFORM_OFFSET_SHIFT)
+
+struct vfio_platform_region {
+        u64                     addr;
+        resource_size_t         size;
+        u32                     flags;
+        u32                     type;
+#define VFIO_PLATFORM_REGION_TYPE_MMIO  1
+#define VFIO_PLATFORM_REGION_TYPE_PIO   2
+};
+
 struct vfio_platform_device {
+        struct vfio_platform_region     *regions;
+        u32                             num_regions;
+        int                             refcnt;
+